1. Site Description
2. Geology
3. Access
4. General Assessment:
5. Associated Sites
6. Safety Information
7. Supplementary Information
8. Industrial History and Archaeology
9. Bibliography
10. Maps
11. Surveyors

This page still under construction.

Site Description

Grid Reference: NZ 751 198 to 783 191
BGS Sheet: 34
OS Sheet: 94

Site Status: Heritage Coast (Not RIGS, other references Nos. 55 and 80). Open access.

Description of Geodiversity: West of Boulby the cliffs rise to over 200m O.D. with the upper parts being formed of the old Boulby and Loftus Alum Quarries. These are SSSIs and, also for access reasons, are described separately. Between Boulby and Cowbar can be found superb sea cliffs and rocky foreshore (scar) with extensive Lias Group exposures. Much historical and industrial archaeological interest. The Cleveland Way passes along the cliff top.

View of Cowbar Nab from Staithes Harbour showing beds of the Staithes Formation capped by glacial 'till'.

Geology

With shallow dips, the strata that can be examined directly in situ are limited to the uppermost beds of the Redcar Mudstone Formation and the base of the Staithes Sandstone Formation. In the past, there were tracks down the cliffs that enabled geologists to study the full section easily.

• Whitby Mudstone Formation: This forms the upper part of the sea cliffs at Boulby with the alum shale quarry at about 130m O.D.
• Cleveland Ironstone and Staithes Sandstone Formations: These form the main cliff faces.
• Redcar Mudstone Formation: This forms the base of the cliffs and the scar. It is part of the Ironstone Shale, the uppermost, informal sub-unit, and consists principally of sandy, silty shale with conspicuous ironstone and calcareous beds and nodule bands (some remarkably like cannon balls).

Geomorphology: The cliffs for about 2 km to the west of Cowbar Nab are capped by glacial till, bedrock being at 40 to 50m O.D. Staithes Beck has cut a deep channel through the till in to the solid strata. On the coast, several landslips and rockfalls can be seen and, in contrast, examples of slow, gradual marine erosion. The marine erosion has been the subject of detailed studies by Agar (1960) and by Durham University in recent years.

Historical geology: This is the site of 19^th century measured sections by Rev. George Young, John Phillips, Lewis Hunton and others.

Industrial Archaeology:

• The cliffs form the seawards edge of Main Seam (Cleveland Ironstone Formation) underground workings of Boulby and Grinkle Ironstone Mines.
• With regard to the alum industry, the landing place (dock) and tunnel (leading to a shaft up to the alum house) are at Hole Wyke (NZ 762 193).

Access

Access to the scar is achieved from the west side of Staithes harbour. Visitors should park in the car park at the top of Staithes Bank (NZ 781 185), follow Staithes Lane north for c.400m before crossing Staithes Beck by bridge (NZ 781 189), then follow the road east to Cowbar Nab.

It is imperative to start no less than 2 hours before low tide and when sea conditions are reasonably calm. Please read the safety information given below and check tide times before setting off.

Access map for Boulby - Cowbar Foreshore showing suggested parking in Staithes and Mean High Water along cliff base.
(Click on map to enlarge.)

General Assessment:

This coastal section is not recommended for general geological studies owing to the access problems. However, the scar at Cowbar Nab is easy to visit at low tide; it forms a small part of the Geologists’ Association Guide No. 34 by Rawson and Wright (locality 1A, page 18 in 3rd edition). It is adventurous to visit the unique alum tunnel (about 2 km to the west) but this must on no account be entered. Children are best taken to the scar on the east side of Staithes, a world-renowned geological location.

Associated Sites

Boulby Alum Quarries (SSSI, Other reference no. 54);
Loftus Alum Quarries (SSSI, Other reference no. 53).
Hummersea (Other reference no. 51).

Safety Information

WARNING: When going along the scar it is imperative to be aware of the tide times and the sea conditions, the sea reaches the cliff foot at high water and the uneven nature of the scar here makes the tide’s inward progress difficult to predict.

The scar is likely to be wet and slippery and there is danger of falling rock from the unstable cliffs. Please remain at least 10 metres from the cliff foot at all times.

A boulder field makes going west beyond Hole Wyke difficult and further westerly progress should be avoided.

Disclaimer: Tees Valley RIGS Group cannot be responsible for the safety of anyone visiting this coastal site. The accompanying map was accurate when this trail was devised in 2011, but these cliffs are prone to landslip through natural processes and paths may be lost.

A NOTE ON FOSSILS

Please feel free to collect loose fossil specimens weathered from their places of original deposition. However, to enable future scientific study, and for the enjoyment of others who may follow in your footsteps, in situ fossils (i.e. those still embedded in their position of original deposition) should not be collected, but their positions noted and details passed on to TVRIGS, a local museum or other similar body.

Please follow the Countryside Code. Do not light fires. Take any litter home.

Supplementary Information

Geology

Structure: The succession is shown in the cross-section. The beds dip at a slight angle to the east at Cowbar Nab and then swing to a more southerly direction at Boulby and beyond with the result that, going westwards from Cowbar Nab, one is gradually descending the Redcar Mudstone Formation succession.

Section through Boulby Cliff showing the dip of the beds to the south.

Whitby Mudstone Formation (marine, in part anoxic): The Hard and Mulgrave Shale Members are present high up in Boulby Cliff. Fallen blocks, mainly of calcareous and sideritic nodules, can be examined on the scar.

Cleveland Ironstone Formation (shallow marine, even shoaled, oxidic, ironstone formed under slow sedimentation): The various ironstone seams can be seen high in the cliff face below Boulby Quarry and particularly the Pecten and Main Seams. Measured sections were made by various geologists using the tracks down to the beach (e.g Bewick, 1861, Chowns, 1968).

Staithes Sandstone Formation (shallow marine, with tidal influences and storm surges) This forms the main part of Cowbar Nab and the lower part of the cliffs westwards. It is about 25m in thickness and consists principally of siltstones and fine-grained sandstones. Beds 1 to 10 of Howarth’s (1955) sequence of 23 beds are accessible on the west side of the harbour and the remainder on the scar to the east. Measured sections are recorded by Tate and Blake (1876, referred to as ‘Colburn Nab’) and Barrow (1888). Modern detailed descriptions are available by, for example, Howarth (ibid), Howard (1985), Knox et al. (1990, Figure 21), Rawson and Wright (1995, Fig. 22) and Hesselbo and Jenkyns (1995, Figures 25 & 26).

Rawson and Wright (ibid) reported that, as seen at Cowbar Nab;

"the dominant lithology in the lower beds is an intensively bioturbated, argillaceous silty sandstone, with occasional thin (1-35 cm), almost unbioturbated fine sandstones. The latter exhibit delicately-preserved bedding structures, including parallel lamination, low-angle cross-lamination and wave ripple lamination. They have erosive bases, sometimes down-cutting to form small channels".

Knox et al. (ibid) comment that the beds form;

"a fining-up sequence of intensely bioturbated sandy siltstones and siltstones containing laterally discontinuous scour-like tempestites".

Fossils are mostly restricted to shelly lenses.

According to Hesselbo and Jenkyns (ibid) individual beds (and particularly the basal ‘Oyster Bed’) can be correlated closely with those exposed at Robin Hood’s Bay.

Redcar Mudstone Formation (marine): At Cowbar Nab the sequence is transitional and the top of the Formation is taken arbitrarily at the base of the ‘Oyster Bed’ (c.30 cm thick). The 20m logged sequence at Cowbar Nab (Knox et al. ibid, Hesselbo and Jenkyns ibid, their figure 25) consists of silty mudstone passing up to muddy siltstone with graded layers and very fine-grained sandstone with the ‘Oyster Bed’ at the top. Bed 21 (in Hesselbo and Jenkyns log at 20m below the ‘Oyster Bed’) is an ooidal ironstone also seen at a similar level in Robin Hood’s Bay and drawn to their attention by J. Senior. Tate and Blake (ibid) also refer to, what may be the same, ooidal ironstone, 8 or 9 inches (~0.2m) thick at Red Nab and Barrow to a ‘white ironstone’ 40 feet 6 inches (12.3m) below the ‘Oyster Bed’.

Chronostratigraphy (from Hesselbo and Jenkyns ibid):

• Staithes Sandstone Formation (Prodactylioceras davoei zone, Oistoceras figulinum subzone (22m), Androgynoceras capricornus subzone (~2m at base).
• Redcar Mudstone Formation (Prodactylioceras davoei zone, Androgynoceras maculatum subzone).

Fossils lists specific to these localities are in Tate and Blake (ibid) and Barrow (ibid) but note that most have since been renamed.

Geomorphology: For about 2 km west of Cowbar Nab, where the cliffs are capped by till, marine erosion consists of a combination of gradual wearing away of material giving rise in particular to a notch just above high water mark, with more substantial joint/fault/bedding-controlled fracturing resulting in rockfalls, and landslippage of the much less coherent till (Agar, 1960, Hemingway, 1982). Slight variations in competence and fracture patterns have resulted in the formation of several small coves and nabs.

Further west, below the higher Boulby Cliffs, there have been several landslips and rockfalls reported during and since the period of alum working that have carried away parts of the works and particularly the tracks down to the shore. Elsewhere, such as, for example, at the western end of the alum quarry (Sallow Tree Plain) the cliff erosion has been limited at least for the past 150 years.

The ground between the Boulby and Loftus Quarries illustrates how the original cliffs may have looked.

The erosion has been studied in recent years by D. Pybus (see Appleton, 2010) and a team from Durham University.

Historical geology: These sea cliffs and Boulby Quarry above are where several 19^th Century and, since then, other geologists haves made measured sections, making use of the tracks down to the shore. That by Louis Hunton (1836) is the most notable as he was one of the first to recognize the importance of collecting fossils in situ and relating the fossils found to the beds in which they occur.

View of the cliffs looking west from Sandy Wyke. Redhouse Nab can be seen slightly left of center.

Industrial History and Archaeology

Alum: The alum works dates from the 1650s. It closed in 1871. The alum house was at NZ 761 190 on the cliff top. There was a liquor conduit from the quarries and tracks and a shaft and tunnel from the house down to the dock at Hole Wyke (see section on Boulby Quarry). The history and industrial archaeology of the alum works has received much attention in recent years.

The tunnel entrance was lost to view for many years owing to landslippage and was rediscovered by Owen (1990) when it reappeared as a result of the eventual erosion of the loose, landslipped material. Owen and others (especially Morris and Whitlock, 2005) have made detailed surveys as more of the archaeology has been revealed. The entrance and associated ‘rooms’ have now been largely lost to the sea and the real start of the tunnel in bedrock is now revealed.
The microbiology of adjacent weathered shale has been studied by Cockell et al., 2011.

Western tunnel in the cliff at Hole Wyke, beneath the former Alum House as seen on 11th March 2007.

Ironstone: The Main Seam of the Cleveland Ironstone Formation has been worked extensively from:

1. Boulby Mine (1903-1934), miners’ drift entrance at NZ 754 191, and
2. Grinkle Mine (1865-1934) drift at NZ 762 177.
   (Boulby ironstone mine main haulage drift is now under the surface buildings of Cleveland Potash mine and the fan shaft is near the railway at NZ 757 179).

The Main Seam typically consisted of a Top Block ~1m, Shale 0.3m and Bottom Block 0.7m. Waste was tipped in to the sea from a drift exit on the sea cliff at NZ 762 190.

It is likely that there was some earlier ironstone working involving the collection of material from the beaches; 2 drifts in the cliff face are shown by the Geological Survey (Yorkshire sheet IX, 1878) at approximately NZ 753 194 and 755 196).

Current mining: Cleveland Potash mine (at NZ 762 184) is of major importance to the local and national economies. Production started in 1973 and production is of the order 1 million tonnes per year of potash as well as common salt. The workings extend over a wide area that includes Boulby Quarry at a depth of around 1100m below sea level.

The discharge tunnel shaft is on the cliff top at NZ 765 190.

Bibliography

Maps

Geological Survey Yorkshire Sheet IX SW, Rockcliff. scale 6 inches to 1 mile, 1878 (Ordnance Survey 1856).
Notes on the Lower Lias, Main Seam and Dogger. 13 Steeping pits at Sallow Tree with cisterns, various buildings and reservoirs. Rockcliff (Pithill) building shown with various paths and reservoirs.

Geological Survey Yorkshire Sheet IXX NW, Boulby, Runswick & Kettleness scale 6 inches to 1 mile, 1899 (Ordnance Survey 1856).
Detailed layout plan of alum house.

Geology & Geomorphology

Agar, R. 1960. Post-glacial Erosion of the North Yorkshire Coast from the Tees Estuary to Ravenscar. Proc. Yorks. Geol. Soc., 32, 409-428.
A valuable study of coastal erosion but subject to much, perhaps mistaken, criticism by Hemingway and others.

Appleton, A. 2010. The Ice Age and its Aftermath in Eastern Yorkshire: One possible interpretation of the evidence. Unpublished review, 33p. (in Whitby Lit. and Phil. Library).
An important contribution collating many views on the ice age and including data on marine erosion.

Barrow, G. 1888. The Geology of North Cleveland. Mem. Geol. Survey, H.M.S.O., London, 101p.
Pages. 9 and 12 show the Redcar Mudstone and Staithes Sandstone Formation sequences.

Bewick, J. 1861. Geological Treatise on the District of Cleveland in North Yorkshire, etc. Reid, Newcastle-upon-Tyne, 194p.
Page 191 shows the measured ironstone section.

Chowns, T. M. 1968. Environmental and diagenetic studies of the Cleveland Ironstone Formation in north-east Yorkshire. Thesis, University of Newcastle upon Tyne.
Page 337 has the measured section at Rockcliff.

Cockell, C. S. et al. 2011. Molecular characterization and geological microenvironment of a microbial community inhabiting receding shale cliffs. Microb. Ecol. , 61, 166-181. Samples taken from shale in the alum tunnel.

Fox-Strangways, C. 1892. The Jurassic Rocks of Britain, Volume 1. Yorkshire. Geol. Survey, H.M.S.O., London, 551p.
Similar to Barrow, 1888.

Hemingway, J. E. 1982. Chapter 1 in Prehistoric and Roman archaeology of north-east Yorkshire ed. D.A. Spratt. BAR British Series 104, 7-31.
A useful account of the eminent professor’s views on glaciation, cliff erosion, etc.

Hesselbo, S. P. And Jenkyns, H. C. 1995. A comparison of the Hettangian and Bajocian successions of Dorset and Yorkshire. From Taylor, P. D. (ed.), Field geology of the British Jurassic, Geological Society, London, 105-150.
Very detailed account. Includes lithic logs of ~20m of the Redcar Mudstone Formation, Ironstone Shale and all the Staithes Sandstone Formation at Staithes (page 138). They report long distance correlation of individual beds, for example, with those at Robin Hood’s Bay and, incredibly, Dorset.

Howard, A. S. 1985. Lithostratigraphy of the Staithes Sandstone and Cleveland Ironstone Formations (Lower Jurassic) of north-east Yorkshire. Proc. Yorks. Geol. Soc. 45, 261-275.
Detailed description, classificationand mode of formation.

Knox, R. W. O’B, Howard, A.S., Powell, J. H. And van Buchem, F. S. P. 1991. Lower and Middle Jurassic Sediments of the Cleveland Basin N. E. England: shallow marine and paralic facies seen in their sequence stratigraphic context. Field guide no. 5, 13th International Sedimentological Congress, Nottingham. 66p.
Day 2 (at Staithes) covers Cowbar Nab including ~6m of the Redcar Mudstone Formation.

Rawson, P. F. and Wright, J. K. 1995. Jurassic of the Cleveland basin, North Yorkshire. From Taylor, P. D. (ed.), Field geology of the British Jurassic, Geological Society, London, 173-208.
Excursion 5 covers Cowbar Nab.

Rawson, P. F. and Wright, J. K. 2000. The Yorkshire Coast. Geologists’ Association Guide No. 34, 3rd revised edition., 130p.
Itinerary 1, Staithes to Port Mulgrave is on pages 16 to 24 and locality 1A is Cowbar Nab.

Tate, R. and Blake, J. F. 1876. The Yorkshire Lias. John Van Voorst, London, 475p.
Pages 89-101, especially page 97, detail the A. capricornus (now P. davoei) zone. Pages 132and 133 show the ironstone section as seen on the path to the shore.

Historical geology

Goldring, D. 2007. Louis Hunton and Loftus Alum Works. Cleveland Industrial Heritage No. 21, 9-15.
Includes a copy of Hunton’s famous section emphasising points of industrial interest.

Hunton, L. 1836. Remarks on a section of the Upper Lias and Marlstone of Yorkshire, etc. Trans. Geol. Soc. London, 5, 215-220.
This is Hunton’s classic paper and includes his section at Boulby, undoubtedly the best by the early 19th Century geologists.

Phillips, J. 1829. Illustrations of the Geology of Yorkshire, etc. Part 1: The Yorkshire coast. Private publication, York, 192p. (2nd Edition 1835 and 3rd Edition 1875, edit R. Etheridge).
Classic account. Section no. 9 shows some detail at Boulby.

Torrens, H. S. and Getty, T. A. 1984. Louis Hunton (1814-1838). English Pioneer in Ammonite Biostratigraphy. Earth Sciences History, 3, 58-68.
A biography stressing the scientific importance of Louis Hunton.

Young, G. and Bird, J. 1822. A Geological Survey of the Yorkshire Coast. Clark, Whitby, 332p. (2nd edition 1828).
The classic measured section at Boulby is on page 134 in the 2nd Edition with the Whitby Mudstone Formation divided into 3 units.

Industrial History & Archaeology

Alum

Barton, P. 2004. Boulby Alum Works: Ways down to the beach. CIAS Newsletter No. 86, 13.
Refers to R. Jackson’s journal items from 1757 to 1783.

Chapman, S. K. 1975. Excavations at the Boulby Alum Works. Cleveland Industrial Archaeology Soc., 2, 23-47.
One of the first industrial archaeological accounts of an alum works.

Chapman, K. 2002. Boulby Alum Works. Chapter 6 in Steeped in History (ed. Miller, I.), North Yorks Moors National Park Authority, 61-74.
A revised account of the 1975 work with major additions and maps by English Heritage.

Featherston, G. R. 2004. Boulby: More on ways down to the beach. CIAS Newsletter No. 86, 13-15.
Adds to Goldring, 2004. See also 18, 19 for photos by J. K. Almond dated 5/8/2004

Goldring, D. 2004. Boulby Alum Works. Ways down to the beach. CIAS Newsletter No. 85, 12,13.
Discussion of the two alum roads to the beach and the shaft and tunnel.

Goldring, D. 2006. Boulby Alum Tunnel. Cleveland Industrial Heritage no. 19, 20.
Brief description of tunnel seen in 2004.

Jecock, M. 2009. A Fading Memory: the North Yorkshire coastal alum industry in the light of recent analytical field survey by English Heritage. Industrial Archaeology Review, 31, 54-73.
General review of the alum industry, including several pictures of Boulby.

Morris, C. H. and Whitlock, S. 2005. Boulby Alum Works’ Tunnel Revisited. Cleveland Industrial Archaeologist No. 30, 29-45.
A detailed industrial archaeological appraisal based on visits between August 2004 and January 2005.

Owen, J. S. 1990. The Tunnel and Shaft for Boulby Alum Works, some features briefly exposed. CIAS Newsletter No. 51, 3-6.
Report on first exposure of the tunnel since being covered by a landslip for many years.

Owen, J. S. 1991. As above, CIAS Newsletter No. 53, page 6.

Owen, J. S. 1995. Continuing clearance at Boulby alum works beach tunnel. CIAS Newsletter No. 62, 3-6.
Further comments.

Owen, J. S. (CIAS Editorial Board). 1998. Cleveland Ironstone. A Memorial to John Owen. CIAS & NYMNP Authority, 103p.
Pages 81-84 are on the Boulby tunnel, etc. based on the CIAS Newsletter references.

Quinn, K. 2009. Boulby Alum. The works diary of George Dodds, 1772-1788. Cleveland Industrial Archaeology Society Research Report No. 9, 76p.
A detailed, primary historical account of operations at Boulby.

Ironstone

Chapman, S. 1997. Boulby Ironstone Mine. Peter Tuffs, Guisborough, 40p.
Account of ironstone mining at Boulby and description of surface remains.

Marley, J. 1857. Cleveland Ironstone, etc. North of England IME Trans., 165-219.
Early, 19th Century ironstone working.

Tuffs, P. 1996. Catalogue of Cleveland Ironstone Mines. Peter Tuffs, Guisborough, 56p.
General details of the mines; booklet (Cleveland Ironstone Series) specifically on Grinkle Mine to be published during 2011.

Abandonment Plans (at Teesside Archives)

Boulby (1 plan), abandoned 2/7/1934. Reference No. 11232

Grinkle (4 plans), abandoned 21/6/1934. Reference No. 11261

Surveyors

Denis Goldring 2011

Please Note: Tees Valley RIGS Group cannot be held responsible for the content of external sites.

©2011 Tees Valley RIGS Group.

1. Site Description
2. Geology
3. Access
4. General Assessment:
5. Associated Sites
6. Safety Information
7. Supplementary Information
8. Geology
9. Industrial History and Archaeology
10. Literature References
11. Mini Geo-trail
12. Surveyors

Site Description

Grid Reference: NZ 736 200 to 744 200
BGS Sheet: 34
OS Sheet: 94
Forwarded as RIGS: 30/09/2003

Site Status: SSSI (Not RIGS, other reference No. 53). Open access (National Trust).

Description of Geodiversity: Extensive former alum quarries of great historical and industrial archaeological interest. The Cleveland Way passes around the southern edge, along the top of the quarry back wall that is nearly 200m O.D. The coastal scenery is impressive.

Looking west through Loftus Quarries from near the Cleveland Way.

Geology

With shallow dips, the Jurassic strata that can be examined directly in situ are limited to beds near to the top of the Redcar Mudstone Formation. Higher beds in the cliff faces can be viewed and examined as fallen blocks.

• Saltwick Formation: This forms the southern back wall of the quarry, some 750m in length and over 30m in height. It is formed predominantly of river channel sandstones. It is difficult to reach and is best examined closely from fallen blocks.
• Dogger Formation: This is about 4m thick and is unique re. coastal exposures. It consists mainly of murchisonae shale and is one reason for the location being SSSI. The apparent transitional beds upwards to Saltwick Formation flood plain deposits are an important source of fossil plants.
• Whitby Mudstone Formation: There are extensive exposures of the lower beds that form the quarry floor (including some Mulgrave Shale).
• Reason for SSSI Status: (1) Occurrence of murchisonae shale, (2) Finding of various reptilian species. (Note: the SSSI status is named as Boulby but the site plan includes both Boulby and Loftus. The murchisonae shale only occurs at Loftus and the pterosaur is also from there. However, the other reptiles may have come from Boulby.)

View from within Loftus Quarries looking west toward Cattersty.

Geomorphology: Several past and potential landslips and rockfalls can be seen and, in contrast, examples of slow, gradual subaerial cliff erosion.

Historical geology: Lewis Hunton’s family were alum makers and estate agents here. Hunton’s study of the stratigraphy at Boulby Quarry, immediately to the east, was a major contribution to the development of geological science.

Industrial Archaeology:

• The quarry is a major alum site with several stages of development. However, industrial archaeological remains are somewhat sparse especially in comparison with Boulby.
• The quarries are underlain by the extensive underground workings of the Main Seam (Cleveland Ironstone Formation) of Loftus Mine that are exposed along the sea cliffs. Jet workings are also present along the sea cliffs not far below the lowest alum levels.

Access

The main access point is at NZ 735 198 where a track into the quarries branches off the Cleveland Way. This point can be reached on foot in various ways but particularly by following the Cleveland Way eastwards from Skinningrove where there is parking (see the mini-geotrail).

Access map for Loftus Quarries showing suggested parking in Skinningrove, extent of Boulby SSSI and North York Moors National Park.
(Click on map to enlage)

General Assessment:

The quarries are an excellent venue for demonstrating Lower and Middle Jurassic geology and industrial archaeology (alum workings).

Associated Sites

Boulby Alum Quarries (SSSI, other reference no. 54);
Hummersea sea cliffs and foreshore (Heritage Coast, other reference no. 51);
Boulby and Cowbar Nab Cliffs ((RC5, other reference no. 80);

Safety Information

PLEASE NOTE: Due to the presence of high unfenced cliff faces we suggest that this site is not suitable for visits by unsupervised children. Please remain well away from the cliff edge and ensure any dogs are kept on a lead. Because of their unstable nature these cliffs must not, under any circumstances, be climbed.

Disclaimer: Tees Valley RIGS Group cannot be responsible for the safety of anyone visiting this coastal site. The accompanying map was accurate when this trail was devised in 2011, but these cliffs are prone to landslip through natural processes and paths may be lost.

A NOTE ON FOSSILS

Please feel free to collect loose fossil specimens weathered from their places of original deposition. However, to enable future scientific study, and for the enjoyment of others who may follow in your footsteps, in situ fossils (i.e. those still embedded in their position of original deposition) should not be collected, but their positions noted and details passed on to TVRIGS, a local museum or other similar body.

Please follow the Countryside Code. Do not light fires. Take any litter home.

Supplementary Information

Geology

Structure: The succession is shown in the accompany section. The beds dip about 3° to the south.

Section through Loftus Quarries showing the general dip of the beds to the south.

Saltwick Formation (deltaic/alluvial): This forms the impressive back wall of the quarry and consists principally of massive lenses of river channel sandstone. It is generally difficult to reach owing to the fallen rock. Blocks, some extremely large, can be readily examined showing sedimentary structures such as cross-bedding and the imprints of plant remains.

Dogger Formation (marine incursion): The peculiar nature of this Formation at this locality was, perhaps, first noticed by Hunton (1836) who reported 10ft (3m) of shale at the top of the succession distinct from the Alum Shale. Later, Tate and Blake (1876, page 26) and Barrow (1888, page 43) described the section in some detail. Tate and Blake provide a lengthy fossil list of 20 species from bed 11, a 3 inch (7.5cm) thick bed described as ‘impure limestone dogger’ and reported Ludwigia murchisonae (an Aalenian zone ammonite) from bed 10 (‘shale’, 1 ft 6 ins (46 cm)) that is directly above.

The geology was subsequently investigated by Black (1929 and 1934) and has been summarised by Rastall and Hemingway (1940). Black’s section is also shown in the British Regional Geology, East Yorkshire and Lincolnshire (1948, page 38). Black records about 11ft (3.3m) of murchisonae beds with a basal ‘pebble bed’ (mainly of mudstone) overlain by ferruginous shale with bands of siderite mudstone nodules, some of which are fossiliferous with the basal bed carrying the zone fossil. The beds are overlain, apparently without any break, by flood plain deposits ascribed to the Saltwick Formation and including coaly shale and fossil plant beds. They are also cut out laterally by channel sandstone that passes laterally into a thin bed of sandstone above the plant-rich layers.

The locality is described by Tate and Blake as “…due north of Upton…”, i.e. at the extreme western end of the quarries at NZ 737 198, but is now rather difficult to reach and is in a poor state.

No comparable localities are known along the coast but similar beds are found inland especially at Cold Moor where they overlie the limestone-rich facies type that is also of murchisonae age. This implies that at Loftus Quarries there is a considerable gap in the stratigraphic succession with several missing time zones at the level of the pebble bed.

Alum Shale and Mulgrave Shale Members (marine, recovering from the anoxic event of the Jet rock): Some 30m of beds are exposed at various sub-quarry levels along the northern, seawards side. They probably belong to the Hard Shale sub-unit of the Member and beds below, the Bituminous Shale sub-unit of the Mulgrave Shale. They consist of weathered, friable, grey, iron-stained, poorly bedded, flaky shale with vertically disposed, small-scale jointing. Fossils, chiefly poorly preserved belemnites, are uncommon but, when seen, may be present in clusters. Small acicular crystals of iron-stained gypsum are common.

Occasional beds of lighter grey, calcareous, sometimes septarian, nodules are common and in places the bare shale surface is littered by loose pieces of these nodules. However, so far, Howarth’s (1962) detailed lithostratigraphic succession has not been elucidated. It is likely that the beds exposed belong to the lower part of the Member (the Hard Shale sub-unit) and to the upper part of the Mulgrave Shale Member.

The upper sequence of the Alum Shale Member is mostly obscured by waste dumps and rock falls but can be seen from a distance in some places. Black (ibid) and Rastall and Hemingway (ibid) report shale with cementstone nodules (and typical Alum Shale ammonites) overlain by about 2 feet (0.6m) mainly consisting of ‘chocolate mudstone’, of ‘doubtful age’, below the Dogger Formation pebble bed.

View Looking west from the eastern end of the quarries showing faces of Alum Shale.

Fossil reptiles: The SSSI description refers to type specimens of two plesiosaurs (Eretmosaurus maccroptera and Thaumatosaurus zetlandicus), one ichthyosaur (Ichthyosaurus crassimonus) and one pterosaur (Parapsicephalus (Schaphognathus) purdoni). The pterosaur was found at Lofthouse (Loftus) by the Rev. D. W. Purdon in 1881 and was described by Newton (Phil. Trans. Royal Soc. London, 1888). It is now at the British Geol. Survey, Keyworth (information from the Pterosaur data base where there are photos).

Geomorphology: The back wall of the quarry has been subject to rock falls and there is now much debris at its foot. At the top, on the Cleveland Way there are open fissures with the quarry wall being in a poor state.

At quarry level on the seawards edge there have been several landslips but also stretches of cliff where there has been little erosion since the publication of the first Ordnance Survey maps. The ground between the Boulby and Loftus Quarries illustrates how the original cliffs looked.

Historical geology: As noted above, Hunton (1836) published an important paper concerning the collection of fossils in-situ and their stratigraphic significance. Hunton’s home was at Hummersea House and he must also have been familiar with Loftus Quarries although his section refers to Rockcliff, Boulby where there was, at the time, an easy track down to the beach.

Industrial History and Archaeology

Alum: The alum works was started in the mid-17^th century and closed in about 1860. There was a major redevelopment about 1800 when a new alum house was constructed by Hummersea beach. The history and industrial archaeology of the alum works has received much attention in recent years and, in particular, there is the major survey by English Heritage (Hunt et al. 2004). The main sites are included in the mini-geotrail.

Ironstone: The Main Seam of the Cleveland Ironstone Formation has been worked extensively under the quarries as part of Loftus Ironstone Mine, the surface works of which are now the Cleveland Ironstone Mining Museum at Skinningrove (at NZ 712 193). The seams typically consisted of a Bottom Block (1.2m) and Top Block (1.5m) separated by a dogger or shale parting up to 0.2 m (but thicknesses varied across the reserve). Tuffs (1996) gives a brief and Chapman (1998) a detailed description.

Literature References

Maps

Geological Survey Yorkshire Sheet IX SW, scale 6 inches to 1 mile, 1878 (Ordnance Survey 1856).
his shows a large number of industrial features that have since disappeared such as several sets of steeping pits and an outline plan of the alum house.

Excursion Guides

Goldring, D. 2001. Along the Scar. Peter Tuffs, Guisborough, 145p. See pages 59-65.

Goldring, D. 2010. Guided Walk to Loftus Alum Quarries 24th July, 2010. CIAS Newsletter No. 100. See pages 5-11.
The mini-geotrail is based on this.

Geology

Barrow, G. 1888. The Geology of North Cleveland. Mem. Geol. Survey, H.M.S.O., London, 101p.
Pages. 9 and 12 show the Redcar Mudstone and Staithes Sandstone Formation sequences. The Main Seam ironstone section at the Old Gut is on page 19.

Black, M. 1929. Drifted plant beds of the Upper Estuarine Series of Yorkshire. Quart. Journ. Geol. Soc. 85.

Black, M. 1934. Sedimentation of the Aalenian rocks of Yorkshire. Proc. Yorks. Geol. Soc., 22, 265-279.
Details of the Dogger Formation succession

Goldring, D. 2011. Geological background to the North Yorkshire alum industry.
Paper in preparation.

Fox-Strangways, C. 1892. The Jurassic Rocks of Britain, Volume I Yorkshire. Geol. Survey, H.M.S.O., London, 551p.
Similar to Barrow, 1888.

Howarth, M. K. 1962. The Jet Rock Series and the Alum Shale Series of the Yorkshire coast. Proc. Yorks. Geol. Soc., 33, 381-418.
The main bed by bed description of the strata, followed by subsequent researchers.

Rastall, R. H. & Hemingway, J. E. 1940. The Yorkshire Dogger, 1. The Coastal Region. Geol. Mag., 77, 177-197 & 257-275.
This is the main detailed description of the Dogger Formation for the Cleveland coast. Pages 192 and 193 refer to the Loftus section.

Tate, R. and Blake, J. F. 1876. The Yorkshire Lias. John Van Voorst, London, 475p.
he measured section and fossil list of the Dogger Formation is on page 26 (cliff due north of Upton hamlet). Pages 132 and 133 show the ironstone section as seen on the path to the shore at Boulby.

Wilson, V. 1948. British Regional Geology, East Yorkshire and Lincolnshire. HMSO, 94p.
Black’s section is reproduced on page 38.

Historical Geology

Hunton, L. 1836. Remarks on a section of the Upper Lias and Marlstone of Yorkshire, etc. rans. Geol. Soc. London, 5, 215-220.
This is Hunton’s classic paper and includes his section at Boulby, undoubtedly the best by the early 19th Century geologists.

Torrens, H. S. and Getty, T. A. 1984. Louis Hunton (1814-1838). English pioneer in ammonite biostratigraphy. Earth Sciences History, 3, 58-68.
biography stressing the scientific importance of Louis Hunton.

Industrial History & Archaeology

Alum

Goldring, D. 2007. Louis Hunton and Loftus Alum Works. Cleveland Industrial Heritage, No. 21, 9-15.
Includes a copy of Hunton’s famous section emphasising points of industrial interest.

Hunt, A. et al. 2004. Loftus alum works, Redcar and Cleveland, Cleveland. An archaeological and historical survey. English Heritage, Survey Report A1/02/2004, 67p.
This is a major survey of Loftus Quarries with detailed plans covering the whole site. It is a pity that there is not more geology, that there are few survey levels and that information on the early 6 inches to 1 mile O. S. maps is missing.

Jecock, M. 2009. A Fading Memory: The North Yorkshire coastal alum industry in the light of recent analytical field survey by English Heritage. Industrial Archaeology Review, 31, 54-73.
General review of the alum industry.

Miller, I. 2002. The Manufacture of Alum: The Collated Evidence. Chapter 9 in ed. I. Miller, Steeped in History. The alum industry of North-East Yorkshire. NorthYorks Moors National Park Authority. 107-120.
A review that includes several references and photos of Hummersea going back to 1993.

Owen, J. S. 1986. Rutways before railways on the Yorkshire coast, with details of twelve sites between Saltburn and Scarborough. CIA No. 18, 23-32.
John Owen’s main record of rutways, etc.

Owen, J. S. (compiled by CIAS editorial board). 1998. Rutways and some other coastal features. (In Cleveland Ironstone (memorial volume)) 75-79. CIAS & NYMNP Authority, 103p
A compilation of John Owen’s finds.

Ironstone

Abandonment Plan (at Teesside Archives) Loftus (1 plan), abandoned 27/06/1959. Reference No. 15168.

Chapman, S. 1998. The Loftus mines, Skinningrove. Peter Tuffs Publications, 100pp.
Account of ironstone mining at Boulby and description of surface remains.

Tuffs, P. 1996. Catalogue of Cleveland Ironstone Mines. Peter Tuffs, Guisborough, 56p.
General details of Loftus mine.

Mini Geo-trail

Click here to view the Loftus Quarries Mini Geo-Trail »»

Surveyors

Denis Goldring 2011

©2011 Tees Valley RIGS Group.

PLEASE NOTE: Tees Valley RIGS Group cannot be held responsible for the content of external sites.

1. Mini Geo-Trail
2. Geo-Trail Map
3. Directions
4. Bibliography

Mini Geo-Trail

In the following route description, notes concerned with navigation are show in plum, descriptions of features able to be seen are in black and warnings are given in red.

Geo-Trail Map

Hummersea mini geo-trail location map showing numbered features of interest and parking (P). Adapted from Along the Scar (2001) (See references).
(Click on map to enlarge)

Directions

• Car Park: On the west side of the Skinningrove Beck mouth at NZ 712 201. Cross the village front and go over the bridge to reach the slipway on the eastern side of the valley.
  
  

  Looking east from the car park across the beck mouth at Skinningrove showing Hummersea Cliff.

  1. There are views of the village, the slag cliffs topped by the iron and steelworks, the incline and the jetty used for the export of pig iron. Further afield, Huntcliff can be seen with the present day mineral railway and the Guibal fanhouse (a much better view is gained by going a little way up the Cleveland Way steps).

 



Looking west from Hummersea Scar showing the slag cliffs (center left), jetty and Cattersty Cliff (midground) and Huntcliff (background).

• Go on to the beach and eastwards on the scar.
  2. The cliff line follows the strike (i.e. the beds are apparently horizontal as seen) and the same strata can be followed for some distance. The ironstone seams gradually appear as the cliffs become higher with the Main Seam at c.60m. At scar level the Redcar Mudstone Formation, silty shale, has thin beds and nodules of ironstone. Rounding Hummersea Point there are two deep clefts in the cliffs, the result of jointing and faulting. There are good examples of rutways on the scar.

 




Members of the RIGS Group and others explore the perched boulders between Skinningrove and Hummersea Steps.

• Continue on to Hummersea Beach, the steps and the ‘kiln’.
  3 The various remains of alum operations noted above can be viewed and the variety of pebbles appreciated.

 




Members of the RIGS Group and others discuss Hummersea Cliff from the beach below Hummersea Steps.

• Continue on the usually wet scar to the Old Gut.
  4. The remains of the dock can be investigated and the ironstone seams of the landslip.The seams have an apparent dip of c.80º to the south! The old line of a track up the cliff can be made out.
  Warning: It’s possible for the intrepid to go on eastwards a short way and, perhaps, find the ‘third dock’ but beware of the incoming tide; there is no easy way up the cliff short of Staithes.

 

• Return to Hummersea Beach and climb the steps and path to the Cleveland Way.
  5. View the geomorphology of this area (much of which has now been donated to Tees Valley Wildlife Trust). The scarp line of Saltwick Sandstone is set back from the coast and is paralleled underground by the subcrop of the Cleveland Ironstone Formation (see the geological map). The, therefore, deep embayment is infilled by till that is much landslipped on the seawards side. The Snilah Ponds, still shown on modern maps, are said to have been infilled by material from Boulby Potash Mine development.

 




View of Hummersea Cliff and Scar (foreground) with Skinningrove Beck mouth and Cattersty Cliff (beyond). The swing in the strike of the beds on the scar is clearly seen. Warsett Hill and Hunt Cliff are in the background with the Guibal fanhouse visible on the cliff top

• Return to Skinningrove along the cliff top following the Cleveland Way. Hummersea House, the home of the Louis Hunton, the famous geologist, is in view to the south-west prior to rounding Warsett Hill.

Disclaimer: Tees Valley RIGS Group cannot be responsible for the safety of anyone visiting the Hummersea site whilst following this geo-trail. The accompanying map was accurate when this trail was devised in 2011, but these cliffs are prone to landslip through natural processes and paths may be lost.

THINK SAFETY

We suggest that you check tide times and weather conditions before setting off, and do so only on a falling tide. Take great care and remain at least 10m away from the cliff base as the cliffs are prone to rock falls. Use appropriate safety equipment where necessary.

Bibliography

See Hummersea site description page »

©2011 Tees Valley RIGS Group.

PLEASE NOTE: Tees Valley RIGS Group cannot be held responsible for the content of external sites.

1. Site Description
2. Geology
3. Access
4. General Assessment:
5. Associated Sites
6. Safety Information
7. Supplementary Information
8. Geology
9. Industrial History and Archaeology
10. Literature References
11. Maps & Plans
12. Surveyors

Site Description

Grid Reference: NZ 755 195
BGS Sheet: 34
OS Sheet: 94
Forwarded as RIGS: 30/09/2003

Site Status: SSSI (RIGS Site Ref: RC5, Site No. 54 [ * Under Review * ]). Open access.

Please Note: The quarry is situated on private land, however spectacular views can be found by walking along the Cleveland Way and other adjacent public footpaths.

Description of Geodiversity: Extensive former alum quarry of great geological, scientific, historical and industrial archaeological interest. The Cleveland Way passes around the southern edge and along the top of the quarry back-wall that rises to over 200m O.D. The coastal scenery is impressive.

View of Boulby Quarries (foreground) showing Cowbar Nab near Staithes (background). Taken from the Cleveland Way above Sallow Tree Plain.

Geology

The quarries form the upper part of a virtually complete Jurassic succession ranging from the Lower Jurassic Redcar Mudstone Formation on the foreshore to the Middle Jurassic Saltwick Formation at the top. The quarried beds of interest to the alum industry constitute principally the Alum Shale Member of the Whitby Mudstone Formation. The beds exposed in the quarries are:

• Saltwick Formation: This forms the southern back-wall of the quarry, some 600m in length and up to 30m in height. It is formed predominantly of river channel sandstones. These exposures are difficult to reach and best examined more closely within the numerous fallen blocks.
• Dogger Formation: This Formation is about 1m thick and consists mainly of siliceous ironstone. It is sometimes absent as a result of washouts, and is now poorly exposed.
• Alum Shale Member: There are good exposures of the lower beds of shale (Whitby Mudstone Formation) which form the quarry floor especially at the western end.
• Reasons for SSI Status: Although the SSSI is named Boulby it actually includes both Boulby and Loftus Quarries. Two significant features, the murchisonae shale facies of the Dogger Formation and the finding of pterosaur remains in the Alum Shale, are at Loftus Quarries but it is likely that other reptilian remains were also found at Boulby.

Geomorphology: Several past and potential landslips and rockfalls can be seen and, in contrast, examples of slow, gradual sub-aerial cliff erosion.

Historical geology: This is the site of 19^th century measured sections by Rev. George Young, John Phillips, Lewis Hunton and others.

Industrial Archaeology:

• The quarry was a major alum site with at least two stages of development – mid-17^th to late-18^th century and late-18^th to late-19^th centuries. Across the site can be found the remains of calcining places, steeping pits, buildings, reservoirs, liquor conduits, etc. The stone revetments at the western end are most impressive.
• There are small ironstone trials of the Top Seam (Dogger Formation).
• The quarry is underlain by the extensive underground workings of the Main Seam (Cleveland Ironstone Formation) that are exposed along the sea cliff face.

Access

Access map for Boulby Quarries showing extent of SSSI and suggested parking.
(Click on map to enlage)

The easiest access is from the east along the Cleveland Way. A minor road off the A174 affords suitable parking.

General Assessment:

The quarry is an excellent venue for demonstrating Lower and Middle Jurassic geology, recent geomorphology, historical geology and industrial archaeology (alum and ironstone workings). The high cliffs require care.

Associated Sites

Boulby Sea Cliffs and Foreshore (North Yorkshire Heritage Coast, RC5, other reference 80.);
Loftus Alum Quarries (SSSI, other reference no. 53).

Safety Information

PLEASE NOTE: Due to the presence of high unfenced cliff faces we suggest that this site is not suitable for visits by unsupervised children. Please remain well away from the cliff edge and ensure any dogs are kept on a lead. Because of their unstable nature these cliffs must not, under any circumstances, be climbed.

Please follow the Country Code. Do not light fires. Take any litter home.

In situ fossils must not be collected, but their positions noted and details passed on to TVRIGS, a local museum or other similar body. Scattered fossils already weathered from the rock may be collected freely.

Supplementary Information

Geology

Structure: The succession is shown in the accompany section. The beds dip about 3° to the south.

Section through the cliff and quarry demonstrating the gentle dip of the beds.

Saltwick Formation (deltaic/alluvial): This forms the impressive back-wall of the quarry and consists principally of massive lenses of river channel sandstone. It is generally difficult to reach owing to fallen rock. Blocks, some extremely large, can be readily examined showing sedimentary structures such as cross-bedding and the imprints of plant remains.

Dogger Formation (marine incursion): This is about 1m in thickness and consists mainly of siliceous ooidal ironstone. However, at the eastern end it is described as ooidal siderite mudstone overlain by dark mudstone with similar mudstone nodules, as a clear result of lateral transition (Rastall and Hemingway, 1940). It is now poorly exposed. Blocks of ironstone can be examined that form a roughly laid wall by an old trial adit.

Alum Shale Member (marine): Some 10m of beds are exposed at various sub-quarry levels especially at the western (Sallow Tree Plain) end of the workings around the stone revetments. They consist of weathered, friable, grey, iron-stained, poorly bedded, flaky shale with vertically disposed jointing on the small scale. Fossils, chiefly poorly preserved belemnites, are uncommon but when seen may be present in clusters. Small acicular crystals of iron-stained gypsum are common. Occasional beds of lighter grey, calcareous, sometimes septarian, nodules can be found but, so far, Howarth’s (1962) detailed lithostratigraphic succession has not been elucidated. It is likely that the beds exposed belong to the lower part of the Alum Shale Member (the Hard Shale sub-unit) or even the upper part of the Mulgrave Shale Member.

Revetment walls at the west end of the site with Cowbar Nab in the background.

Geomorphology: The back-wall of the quarry has been subject to rock falls and there is now much debris at its foot. At the top, on the Cleveland Way there are open fissures with the cliffs being in a poor state. At quarry level on the seawards side there have been several landslips reported during and since the period of working that have carried away parts of the alum works and particularly the former tracks down to the shore. Elsewhere, such as for example at the Sallow Tree Plain (western end) steeping pits the cliff erosion has been limited. The ground between the Boulby and adjacent Loftus Alum Quarries illustrates how the original cliff profile looked.

Historical geology: Boulby Quarry and the sea cliffs beneath (making use of the tracks down to the shore) are where several 19^th century and, more recently, geologists such as Chowns made measured sections. That by Lewis Hunton (1836) is the most notable as he independently recognized the importance of collecting fossils in-situ, and relating the fossils found to the beds in which they occur bolstering the emerging concept of biostratigraphy.

View of Boulby Quarry and cliff as seen from Bias Scar toward Staithes.

Industrial History and Archaeology

Alum: The alum works was started in the 1650s at the eastern (Rockhole Hill) end of the quarry, redeveloped at the western (Sallow Tree Plain) end in 1784, and eventually closed in 1871. The alum house was about 0.5km to the south-east and, as well as tracks, there was a shaft and tunnel here connecting the house to the dock at Hole Wyke (see Boulby Sea Cliffs and Foreshore). The history and industrial archaeology of the alum works has received much attention in recent years (see references).

Ironstone: The Main Seam of the Cleveland Ironstone Formation has been worked extensively under the quarries from:

• (a) Boulby Mine, miners’ drift entrance at NZ 754 191, and
• (b) Grinkle Mine drift at NZ 762 177.

Boulby Ironstone Mine main haulage drift is now under the surface buildings of Cleveland Potash Mine, and the fan shaft is near the railway at NZ 757 179. The Main Seam typically consisted of a Top Block ~1m, Shale 0.3m and Bottom Block 0.7m. Waste was tipped in to the sea from a drift exit on the sea cliff at NZ 762 190. There are two trials of the Top Seam ironstone of the Dogger Formation, one within the quarries and one a short distance to the east (at NZ 758 190).

Current mining: Cleveland Potash Mine (at NZ 762 184) is of major importance to the local and national economies. Production started in 1973 and is of the order 1 million tonnes per year of potash (sylvinite) as well as rock salt (halite). The workings extend over a wide area that includes Boulby Quarry at a depth of around 1100m below sea level.

Literature References

Maps & Plans

Geological Survey Yorkshire Sheet IX SW, Rockcliff, scale 6 inches to 1 mile, 1878 (Ordnance Survey 1856).
Notes on the Lower Lias, Main Seam and Dogger. Shows 12 Steeping pits at Sallow Tree with cisterns, various buildings and reservoirs. Rockcliff (Pithill) building shown with various paths and reservoirs.

Geological Survey Yorkshire Sheet IXX NW, Boulby, Runswick & Kettleness, scale 6 inches to 1 mile, 1899 (Ordnance Survey 1856).
Shows outline plan of the alum house.

Ironstone Abandonment Plans (at Teesside Archives)

Boulby (1 plan), abandoned 2/7/1934. Ref. 11232
Grinkle (4 plans), abandoned 21/6/1934. Ref. 11261

Barrow, G. 1888. The Geology of North Cleveland. Mem. Geol. Survey, H.M.S.O., London, 101p.
Official memoir. Page. 9 shows the Main Seam ironstone section made on ‘the old road now slipped away’. Pages 42 and 43 show Dogger sections.

Chapman, S. K. 1975. Excavations at the Boulby Alum Works. Cleveland Industrial Archaeology Soc., 2, 23-47.
One of the first industrial archaeological accounts of an alum works.

Chapman, S. 2005. Boulby Alum Works Visit. C.I.A.S Newsletter No. 88, 11-17.
Industrial archaeological excursion guide.

Chapman, K. 2002. Boulby Alum Works. Chapter 6 in ‘Steeped in History’ (ed. Miller, I.), North Yorks Moors National Park Authority, 61-74.
A revised account of the 1975 work with additions and maps by English Heritage.

Fox-Strangways, C. 1892 The Jurassic Rocks of Britain, Volume 1. Yorkshire. Geol. Survey, H.M.S.O., London, 551p.
Similar to Barrow, 1888.

Goldring, D. 2001. Along the Scar. Peter Tuffs, Guisborough, 145p.
See pages 59 to 65.

Goldring, D. 2007. Louis Hunton and Loftus Alum Works. Cleveland Industrial Heritage No. 21, 9-15.
Includes a copy of Hunton’s famous section emphasising points of industrial interest.

Hunton, L. 1836. Remarks on a Section of the Upper Lias and Marlstone of Yorkshire, etc. Trans. Geol. Soc. London, 5, 215-220.
This is Hunton’s classic paper and includes his section at Boulby, undoubtedly the best by the early 19th Century geologists.

Jecock, M. 2009. A Fading Memory: The North Yorkshire coastal alum industry in the light of a recent analytical field survey by English Heritage. Industrial Archaeology Review, 31, 54-73.
General review of the alum industry, including several pictures of Boulby.

Marley, J. 1857. Cleveland Ironstone, etc. North of England IME Trans., 165-219.
Early, 19th Century ironstone working.

Miller, I. 2002. Steeped in History North York Moors NPA.

Osbourne, R. 1998. The Floating Egg Pimlico.

Phillips, J. 1829. Illustrations of the geology of Yorkshire, etc. Part 1 The Yorkshire coast. Private publication, York, 192p. (2nd Edition 1835 and 3rd Edition 1875, edit R. Etheridge).
Classic account. Section no. 9 shows some detail at Boulby.

Quinn, K. 2009. Boulby Alum: The works diary of George Dodds, (1772-1788). Cleveland Industrial Archaeology Society Research Report No. 9, 76p.
A detailed, primary historical account of operations at Boulby.

Rastall, R. H. & Hemingway, J. E. 1940. The Yorkshire Dogger, 1. The Coastal Region. Geol. Mag., 77, 177-197 & 257-275.
This is the only detailed description of the Dogger Formation for the Cleveland area. Pages 191 and 192 refer to Boulby sections and pages 263 and 264 to the petrography.

Tate, R. and Blake, J. F. 1876. The Yorkshire Lias. John Van Voorst, London, 475p.
Pages 132 and 133 show the ironstone section as seen on the path to the shore. Pages 170 and 175 detail the section in part of the Whitby Mudstone Formation.

Torrens, H. S. and Getty, T. A. 1984. Louis Hunton (1814-1838). English Pioneer in Ammonite Biostratigraphy. Earth Sciences History, 3, 58-68.
A biography stressing the scientific importance of Louis Hunton.

Tuffs, P. 1996. Catalogue of Cleveland Ironstone Mines. Peter Tuffs, Guisborough, 56p.
General details of the mines.

Young, G. and Bird, J. 1822. A Geological Survey of the Yorkshire Coast. Clark, Whitby, 332p. (2nd edition 1828).
The classic measured section at Boulby is on page 134 in the 2nd Edition with the Whitby Mudstone Formation divided into 3 subdivisions.

Surveyors

Denis Goldring 2011

©2011 Tees Valley RIGS Group.

1. Overview
2. Stratigraphy
3. Lithology
4. References

Overview

The Cleveland Ironstone Formation comprises a sequence of marine ironstone seams interbedded with shale and siltstone units which collectively form a part of the Lower Jurassic System of rocks underlying Cleveland and North Yorkshire. Exploitation of the ironstone seams became a major driving force behind the industrialisation of the Teesside district during the mid- to late-1800s.

Image of Staithes showing part of the village (foreground), the east-side harbour wall (middle left) and the headland of Penny Nab (center background). The base of the Cleveland Ironstone commences at the foot of the cliff.

Stratigraphically the formation belongs within the Upper Pliensbachian (Domerian) universal stage. Ironstone seams and accompanying shales may be highly fossiliferous with remains so abundant in parts as to form well-developed shell-beds. Analysis reveals a wealth of shallow-water marine species, some in life position, along with trace fossils including Rhizocorallium burrows well exposed at Old Nab, east of Staithes.

Economicaly Cleveland Ironstone proved to be a crucial catalyst with the power to reinvigorate the flagging commercial fortunes of the River Tees and surrounding district. The occurrence of ironstone in Cleveland has been known about for many centuries with evidence of small scale working predating the occupation of Roman Britain. Despite much early attention, the true extent of the Cleveland ore-field remained a mystery until the late-1840s, when ironmaster John Vaughan (1799-1868) and mining engineer John Marley (1823-1891), traced seams of ironstone along the coast between Staithes and their northerly outcrop on the escarpment of the Eston Hills overlooking the River Tees

Vaughan and Marley’s evidence of a large scale body of workable iron ore in close proximity to both coal and limestone from County Durham, together with the district’s developing communications network by rail and sea, proved a heady concoction. Combine with this an insatiable appetite for manufactured goods driven by the Industrial Revolution and a cohort of shrewd opportunist business speculators, and it may come as no surprise that Middlesborough developed rapidly. The town grew from a mere idea in the late-1820s, to become the commercial centre of one of the world’s greatest iron and steel producing regions in little over two generations. By 1881, the year of Middlesborough’s Golden Jubilee, output of ironstone drawn from the Cleveland ore-field exceeded 6,000,000 tons (6,096,360 tonnes).

Stratigraphy

Formerly classified as part of the Middle Lias, these strata were deposited over a period of ~2 million years, as soft sediment on the floor of a shallow arm of the ancient Tethys Ocean, between c.185 million and 183 million years before present. The formation lies conformably on the prolifically-fossiliferous shallow marine sandstone, siltstone and mudrock of the Staithes Formation. There are six named ironstone seams which are, in order of deposition, the Osmotherly, Avicula, Raisdale, Two-foot, Pecten and Main Seams.

At its type locality, on the coast around Staithes, North Yorkshire, the formation attains a thickness of 25.3 metres and comprises five ‘coarsening-upward’ cycles of marine shale and siltstone each capped by a seam of ironstone of varying thickness, composition and iron-content. The shales and siltstones are grey in colour, and exhibit occasional bands of calcareous or sideritic nodules, shell-beds and cross-bedding. The uppermost reaches of some of the shale units may be laminated and have been dubbed tempestites. Immediately beneath the Raisdale Seam at Staithes can be seen laminated beds with basal gutters up to 0.5 metres wide and 5 metres long which were scoured out during high energy storm events. The gutters have been subsequently infilled with fine sand and silt which shows signs of pyritisation. These features tend to be oriented in an east-west direction and are fairly persistent laterally, occurring almost 19 kilometres to the south-east at Hawsker Bottoms.

Definitive zonal work has been carried out on the coast by Howarth (1953, Howard (1985) and extended inland by Chowns (1968). Their efforts reveal that these strata span two faunal zones prompting subdivision into corresponding informal units. The lowest 19 metres are predominantly shaley and include the Osmotherly, Aviclua, Raisdale and Two-foot Seams, the best-developed being the Avicula Seam attaining c.0.5 metre at Jet Wyke. They reside within the upper part of the Amaltheus margaritatus faunal zone and are collectively referred to as the Penny Nab Member, after a headland c.150 metres east of Staithes Harbour.

An unconformity marks transition to the overlying Pleuroceras spinatum zone which covers the more ferruginous upper 6 metres of the formation. It is referred to as the Kettleness Member, and includes the Pecten and Main Seams, the latter c.1.8 metres thick and split into a 0.7 metre Top Block and 0.8 metre Bottom Block by 0.3 metre of medial shale at Old Nab.

The most important seams, from an economic perspective, are the Main and Pecten Seams which attain their greatest development along the northern edge of the ore-field, near Eston. There the Main Seam, 3.66 metres thick, rests directly on the Pecten Seam (1.23 metres) which includes an impressive shell-bed. The seams are relatively persisted in an east-west direction, but shale-partings intervene and thicken to the south at the expense of the ironstone. In East Cleveland the strata pass through a structural syncline known as the Skelton Syncline where the Main Seam descends to around 125 metres below sea level around North Skelton.

The whole formation thins and becomes less-ferruginous to the south as the Main Seam, itself much diminished, oversteps each of the underlying seams one-by-one. Strata of this age are completely absent at the southerly limit of the Yorkshire Basin around Market Weighton.

Lithology

On average the Cleveland Ironstone Formation comprises around 70% shale and 30% ironstone though the latter occurs in the form of the six named seams of variable thickness. The ironstone is classed as being low-grade with an iron-content of up to 33%, and is deemed economically viable only above ~27%.

Close-up of a sample of Cleveland ironstone from Kilton Mine demostrating the rock's oolitic texture.

The primary iron-bearing minerals are the iron carbonate siderite (FeCO₃) and berthierine (formerly know as chamosite, (Fe₂²⁺ Al(Si,Al) O₅(OH)₄). Ancilliary components include calcite (as MgCO₃ and MnCO₃), pyrite (FeS₂), collophanite (Ca₃P₂O₈ H₂O ), silica (Si), clay minerals and derivatives such as octahedrite (brookite) (TiO₂), and dickite (Al₂Si₂O₅(OH)₄). The seams are often oolitic, especially in the north of the district, but vary in constitution across the ore-field. The ooids (on average) comprise ~33% siderite, ~33% berthierine, and a similar proportion of ancilliary minerals and demonstrate deformation whilst the sediment was still plastic.

The origins of the ironstone seams have been the subject of much argument and counter-argument since their large scale exploitation commenced in the mid-1800s. The most widely accepted solution emerged in the 1920s following analysis by Hallimond (1925). It was discovered that overall iron-content in both the shale and the seams was roughly equal. This suggests that the concentration of dissolved iron within the surrounding sea-water remained roughly the same during deposition of both shale and ironstone. The physical differences between the two arises as the result of variations in sediment influx. Rapid rates of sediment input caused deposition of the shales, whereas a diminished rate of input enabled the same amount of iron to be concentrated within a lower sediment load thereby producing the ironstone seams. Evidence of bivalves in life position, Rhizocorallium trace fossils, cross-bedding, episodes of non-deposition and (not least) the oolitic texture all indicate that the ironstones were laid down in shallow water.

Fossils are ubiquitous, especially within the ironstone seams, to the extent that the Avicula^(a) and Pecten seams are named after their most abundant faunal inclusions.

Notes

(a) The genus Avicula has since been reclassified as Oxytoma.

References

1. Goldring, Denis (2001), Along the Scar, Peter Tuffs Publications
2. North, G.A. (1974), Teesside’s Economic Heritage, Cleveland County Council
3. Goldring, Denis (2006), Along the Esk, Peter Tuffs Publications
4. Howarth, M.K. (1953), The Domerian of the Yorkshire Coast, Vol. 30, Proceedings of the Yorkshire Geological Society, p. 147-175
5. Rawson & Wright, P.F & J.K. (1992),The Yorkshire Coast, THE GEOLOGIST’S ASSOCIATION.
6. Howard, A.S. (1985), Lithostratigraphy of the Staithes Sandstone and Cleveland Ironstone Formations (Lower Jurassic) of North-east Yorkshire, Vol. 45, Proceedings of the Yorkshire Geological Society, p. 261-275
7. Hemingway, J.E. (1974), “Chapter 7 – Jurassic”, The Geology and Mineral Resources of Yorkshire, Yorkshire Geological Society, p. 161-223
8. Hallimond, A.F. (1925), Iron Ores: Bedded Ores of England & Wales, Petrography and Chemistry, Vol. 29, Memoirs of the Geological Survey of Great Britain (Special reports on the mineral resources of Great Britain) H.M.S.O.

©2011 Andy Cooper.

PLEASE NOTE: TVRIGS Group cannot be held responsible for the content of external sites.

This mineral is able to assume almost any colour but commonly brown, yellowish-brown, or grey specimens can be found. It occurs in Britain’s Carboniferous strata as nodules and beds of impure iron carbonate known as Clay Ironstone. Once a valuable source of ore, alongside a dark carbonaceous form known as Blackband. In Cleveland the well-known ironstone through which which Teesside became a major industrial force from 1850, is of Jurassic age (c.188,000,000 years old), contains iron-rich berthierene rather than siderite, and occurs with a distinctive texture known as oolitic. An amalgamation of small rounded concentric structures, which form through the same colloidal processes as those reponsible for oolitic limestones, make up the bulk of the rock. Siderite can also be found in massive, granular, or concretionary forms, produced in a variety of environments including within hydrothermal veins along with pyrite and galena, within intrusive pegmatites, and as sedimentary Bog Iron Ore in high latitude lakes and swamps.

At its purest, siderite forms rhombohedral crystals with a vitreous (inclining to pearly) lustre, perfect cleavage, a white streak, and uneven fracture. An allied mineral Hydrated Iron Oxide or Limonite (FeO(OH)·nH2O), commonly forms pseudomorphs (perfect copies) of siderite crystals.

It is however more usually found in the local area as red-weathering nodules within grey mudstone scars, exposing part of the Cleveland Ironstone Formation that crops out on the foreshore at Jet Wyke, Staithes. In the 1700s, such nodules were collected from the scars by local villagers and loaded onto boats which eventually disgorged their cargoes at furnaces on Tyneside, long before the significance of the Cleveland Ironstone Formation was suspected.

Images above are of:
Manganoan Siderite with Albite;
Siderite Pseudomorphosis in Limonite with quartz;
Red Siderite Nodule in Grey Mudstone at Staithes.

Image of the blast furnace at Redcar

Locally the Cleveland Ironstone Formation, deposited in a tropical sea which occupied the Tees Valley during the Jurassic Period around 190 million years ago, was exploited at over eighty mines between 1850 and 1962. The stone’s iron content of around 30% being much less than the high grade ore required today. Its former exploitation led to the founding of a great number of blast furnaces, shipyards, foundries, iron and steelworks along the banks of the River Tees. Cleveland Ironstone was fundamental in the growth of our region as a world centre for the iron and steel trades.

Oolitic Cleveland Ironstone from Kilton Ironstone Mine near Lingdale.

More information about the way in which Cleveland Ironstone was mined can be found on this site here and via The Cleveland Ironstone Mining Museum at Skinningrove.

The place for you to find out more about the geology and industrial heritage of Redcar & Cleveland, Middlesbrough,
Stockton, Hartlepool and Darlington.

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RIGS News

• Tuesday 8th November 2011: November’s Rock of the Month offering can now be viewed by clicking here…

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• Thursday 13th October 2011: The RIGS Group’s recently published Geodiversity Action Plan has been recognised and used as a case study by Geoconservation UK. More details can be seen here and by clicking on the navigation bar at the top of this page.

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• Wednesday 12th October 2011: Why not view Tees Valley Wildlife Trust’s Alum, Alchemy & Ammonites pages.

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• Wednesday 1st June 2011: Our latest Rock of the Month article is now online. We would like to thank RIGS Group member Scott Bradley for providing the article.

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• The group’s expansion into the Darlington district is approaching the end of its first phase. A number of sites have been identified and five summarily surveyed.

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Ramblers walking with the RIGS Group descend Boulby Bank after visiting cliff-side alum quarries near Staithes.

TVRIGS are always keen to recruit new members. So if you have an interest in the region’s geology, would like to find out more about the Tees Valley’s industrial heritage, or simply wonder what all of the fuss is about, then why not join us, it’s free – and we have only the very best biscuits at our meetings…

Unless otherwise stated, all images on this site ©2010 & ©2011 TVRIGS Group.

1. The History of Ironworking in The Tees Valley
2. The Iron Smelting Process
3. The End of Ironstone Mining in Cleveland
4. More Information

The history of local ironstone mining and the development of the Tees Valley are intimately linked.

The History of Ironworking in The Tees Valley

The earliest smelting of ironstone in the area is traceable to c.400BC, and the Iron Age, in addition the Romans are mooted to have mined ironstone from the Eller Beck Formation – dubbed the Julian Band. Later, in the 1200s, there is evidence of furnaces in Eskdale, at places such as Fryupdale and Egton. Heaps of furnace slag around Rievaulx Abbey mark the working of local ironstone by monks, a trade that continued until the mid-1600s. Evidence is then scant for around a century until we learn that nodules and boulders of ironstone were collected in summer from the scars by local coastal communities. The ironstone was loaded onto small boats grounded on the rocks nearby before travelling to furnaces on Tyneside. Such seasonal work provided a welcome financial boost for villagers who usually relied upon fishing to survive. Ironstone collected at Robin Hood’s Bay fed the Whitehill Furnace, founded at Chester-Le-Street in 1745, for around fifty years, and the Tyne Iron Company obtained their stone from various scars between Saltburn and Scarborough until the mid-1800s.

Quarrying began in the late-1820s where the ironstone crops out on the foreshore at Kettleness, and later in Brackenberry Wyke east of Staithes. In 1835, a Mr. Wilson (partner in Losh, Wilson, & Bell – ironmasters on Tyneside) noticed ironstone in a cutting at Grosmont whist inspecting construction of the Whitby & Pickering Railway. Drift mines were soon operating with the stone going by rail to Whitby. Cleveland ore still travelled by sea to Wearside and Tyneside for processing, but all of this was soon to change.

Kettleness viewed from Thorndale Shaft, Port Mulgrave.

When Bolckow & Vaughan sought a local source of ore for their ironworks, erected in 1841 in the young town of Middlesbrough, Cleveland Ironstone was the obvious choice. The opening of a drift mine at Skinningrove in 1848 rejuvenated the search for another source by John Vaughan and, with the help of mining engineer John Marley, the quest moved north-west to Eston. Here, on 8th June 1850, the pair located a quarry from which road-stone had been extracted for some years. On inspecting it, they found that the rock in question was the Main Seam of the Cleveland Ironstone Formation, which here lay some sixteen feet (4.8 metres) thick. Mines were operating before the end of 1850, and thus began the (then) unprecedented growth of Teesside. An “Infant Hercules” beginning its journey to become one of the greatest iron-producing districts in the World.

Bolckow and Vaughan’s success was soon being felt by other mining companies as the extent of the ironstone underlying Cleveland became clear.

Denny Pearson & Dux Hollinworth drill ironstone at Lingdale mine in the1950s.

Soon, shaft mines joined an expanding number of drift mines as the railway made its way into East Cleveland where the ore lies at depths up to 720 feet (220 metres). In 1881, Middlesbrough celebrated its jubilee and the miners in the Cleveland Hills responded with a total production of above six million tons – double the projected output with over a million tons drawn from the Eston mine complex alone.

Headgear at Stanghow Ironstone Mine, Margrove Park, near Boosbeck.

The Iron Smelting Process

Ironstone arrived on Teesside by rail where it was initially placed in kilns, with coal or coke, to be strongly heated (calcined); this had the effect of driving off water and some of the unwanted sulphur resulting a concentration of the iron content from 33% in the raw stone, to c.40%. Next, the ore was placed in a furnace and smelted, with the resulting iron being cast into ingots known as pigs. These would be later re-melted in a puddling furnace and the iron stirred to remove excess carbon making it malleable.

A major by-product of smelting was furnace slag, the disposal of which proved a costly affair for the ironmasters who were forced to rent land upon which to store it. The solution to this problem arose as the result of improvements along the banks of the Tees. Some slag, from the stockpiles along the River, was taken for reclamation schemes and the ironmasters would even pay four pence per ton for its removal. Slag was also cast into bricks in order to construct 22 miles of strong training walls to channel the River more efficiently. More recently, the North and South Gare breakwaters at Teesmouth are constructed upon foundations comprising millions of tons of furnace slag. Other by-products were utilised by the area’s growing chemical industry.

The discovery of a new method of the steel production (the Bessemer process) in the 1850s, which worked better using non-phosphoric ores unlike those available in Cleveland, could have been an early problem. John Vaughan, who engaged the help of two colleagues from Staffordshire to look at the problem, overcame it. They eventually contrived the successful Thomas-Gilchrist Process, by which local stone could be processed into high-grade steel for world markets. This process is still used today in other parts of the world.

The End of Ironstone Mining in Cleveland

The industry’s decline was long and drawn out, commencing at the end of the nineteenth century with imports of cheaper Spanish ore. The intervention of two World Wars kept Cleveland stone flowing from the hills. After WWII, the tenacity and skill of Cleveland miners and ironworkers ensured that the industry might fade, but would never die in this proud region. Despite everything, mining of Cleveland Ironstone finally succumbed in 1964 with closure of the deepest, and last, of over eighty mines in the ore-field at North Skelton.

Fan House, Grinkle Ironstone Mine and used for ventilation of the Grinkle Ironstone Mine which operated from 1865 to 1934. One of the few remains of the mine left, having been obliterated by the Cleveland Potash development. © Copyright Mick Garratt and licensed for reuse under this Creative Commons Licence

Amongst the hills of Cleveland, which once resounded to the sound of steam-powered industry, today stand the peaceful tumbled-down remains of these once great mines. Their ruins, now being gradually reclaimed by nature, resound only to the gentle sounds of birdsong.

Their continuing presence, in addition to the blast furnace at Redcar, works and museum at Skinningrove, and the foundry at Guisborough all bear testament to this region’s rich industrial past.

More Information

Click Here for a more technical treatment of the Cleveland Ironstone Formation »

We would like to congratulate Teesside Cast Products (TCP) on finding a buyer for the Redcar Blast Furnace and welcome SSI to Teesside.

PLEASE NOTE: Tees Valley RIGS Group cannot be held responsible for the content of external sites. 
©2010 Tees Valley RIGS Group

1. Site Description
2. Site Map
3. Site Assessment
4. Surveyors

Grid Reference NZ 643 158
BGS Sheet 34
OS Sheet 94

Forwarded as RIGS 30/09/2003

Site Description

Site Status


Description of Geodiversity Exposures of Main Seam Cleveland Ironstone Formation (bottom block) beside bridge footings below Fox & Hounds public house. A small waterfall immediately upstream may exist due to presence of the Pecten Seam. The area has several faults which affect outcrop and this may be the cause of the Pecten Seam waterfall being sited above the Main Seam outcrop.


The drift of Slapewath Ironstone Mine was situated above and slightly north of the Main Seam outcrop.


Literature References The Floating Egg – Roger Osbourne. 1998

Site Map

Site Assessment

Surveyors

Andrew Carter, Alex Davies