Fossil wood is not usually found associated with the rest of the tree (leaves and roots) and identification can be difficult, in these cases the specimens are given a special botanical name. These usually feature the term xylon, along with the plant type it is assumed to be part of, to show that the identification is not bases on whole specimen. (e.g. Arucarioxylon – linked to the Arucaria (Monkey Puzzle) or related genus)

A well-preserved specimen of fossil wood recovered from the Redcar Mudstone Formation near Staithes.

This example of a piece of fossilised wood was found on the beach near Staithes. It has been preserved through a process known as permineralization. The original piece of wood was buried amongst sediment deposited millions of years ago. Over time the minerals from the rock soaked into the wood and replaced the original organic material, whilst keeping the structure of the wood. (in this case it was part of the Redcar Mudstone Formation which was laid down approximately 190 million years ago).

In the specimen shown above you can still clearly see the growth rings hundreds of millions of years after the tree, which grew on land, was transported by rivers to the ancient Tethys Sea where it eventually became incorporated into the sea floor sediment.

©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. 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. 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. General Description
2. Jewellery
3. Folklore and Medicine
4. Pyrite in the Tees Valley

For this month’s article we are going to take a look at a commonly occurring mineral having a long history of association with humankind. Fool’s Gold is a common name used to describe a number of different minerals including weathered biotite mica, though most frequently the name is attached to iron pyrite [FeS₂], technically known as iron di-sulphide.

General Description

The name pyrite derives from the Greek purites lithos, meaning “stone of fire“, after its tendency to spark when struck against steel, one of several minerals to do so. For this reason it was used in wheel-lock firearms from around the year 1500, before the invention of flint-lock style weapons.

Cubic crystals of pyrite in their matrix.
Image courtesy of Ra'ike.

This mineral is brassy-yellow in colour and has a metallic lustre, thereby outwardly resembling gold [Au] and accounting for its common name. Like any attractive mineral it has accumulated a number of other names. For example, when associated with coal deposits pyrite is dubbed brass, brazzle or brazil.

It occurs as cubic, octahedral, orthorhombic, tetrahedral or pyritohedral crystals, and not infrequently in irregular aggregates of various sizes. Twinning, is common with the orthorhombic variety producing ‘cockscomb’ or ‘spearhead’ arrangements. Pyrite is a very common sulphide mineral and can be found in sedimentary, metamorphic, intrusive, eruptive and hydrothermal deposits commonly associated with other sulphides and oxides. It occurs in mudrock as fine-grained impregnations, detached crystals and aggregates, also in sandstone, coals and schistose rocks. Pyrite can act as a replacement mineral occasionally producing beautiful lustrous fossil specimens. It weathers to produce iron sulphate or the hydrated iron oxide limonite [FeO(OH)]. Other accessory minerals which associate with pyrite include minor amounts of copper, nickel, tin, cobalt and silver.

Sparkling crystals of pyrite demonstrating replacement in this ammonite.
Image courtesy of Didier Descouens.

Pyrite may (very-rarely) be associated with actual gold. Auriferous pyrite (also dubbed arsenopyrite or mispickel) contains arsenic which is able to form a substitution couple with gold within the crystal lattice. This type of deposit can be economically viable and it is worked in both Rossland, British Columbia and Carlin, Nevada, where the pyrite contains up to 0.37wt% gold making it a valuable ore. Carlin’s motto is;

the town originally being founded as a camp-site during the gold-rush of the 1840s.

Native Gold Nuggets
Image courtesy of Aramgutang

In spite of its accusatory common name however, pyrite and gold are rather easy to tell apart, even without the advantage of sight. Pyrite has a density of around 5gm/cm³ but gold a density of between 15 and 19.3 gm/cm³. This means that gold is much heavier in the hand. Pyrite has a hardness of 6 or 6.5 on Moh’s scale, is brittle and difficult to scratch, whereas gold is much softer having a hardness of only 2 or 3 on the same scale and is malleable. If any doubts remains then when a sample is tested on unglazed porcelain, pyrite leaves a black streak whereas gold has a yellow streak.

Modern uses of pyrite are primarily ornamental and industrial, with the sulphide being mined and processed on a large scale to produce both sulphuric acid [H₂SO₄] and ferrous sulphate [FeSO₄] at sites including Rio Tinto (Spain), Sulitjelma (Norway) and Mount Lyell (Tasmania).

A few related minerals may themselves be mistaken for pyrite amongst which we can include;

Chalcopyrite [CuFeS₂] or copper iron di-sulphide is a related mineral outwardly resembling pyrite, and sometimes, along with Bornite [Cu₅FeS₄], dubbed Peacock Ore due to its iridescent surface. It (too) is generally brassy-yellow in colour, but conforms to the tetragonal crystal habit, is slightly softer than pyrite (only 3.5 to 4 on Moh’s scale) and has a green-black streak. Chalcopyrite can be an important ore of copper.

Metallic, brassy-gold twinned crystals of Chalcopyrite.
Image courtesy of Rob Lavinsky

Pyrrhotite is an iron sulphide of variable composition and, like chalcopyrite, is softer than pyrite. It is a darker bronze colour, weakly magnetic and has a greyish black streak.

Jewellery

Pyrite crystals have been found associated with early (Palaeolithic) human collections of precious objects, and the mineral has been used by many civilisations since that time for a variety of purposes including as jewellery. From Ancient Mesopotamian Materials and Industries by P.R.S. Moorey, we learn that;

The Ancient Greeks also used pyrite to manufacture pins, earrings, brooches and mirrors, and it continues to be employed in jewellery-making across the world to the present day.

Marcasite, is a polymorph of iron pyrite. Polymorphs are minerals with identical chemical formulae but which conform to different crystal systems. In this case, marcasite [FeS₂] conforms to the orthorhombic system rather than the cubic or octahedral systems found in pyrite. It is known as white iron pyrite and, as its name suggests, is lighter in colour than pyrite and more brittle due to its different habit. Oddly, marcasite is unsuitable for the making of jewellery as it reacts more readily under humid conditions to form sulphuric acid and iron (II) sulphate, together producing a white powdery deposit of the mineral melanterite [FeSO₄·7H₂O] in a process known to geologists as pyrite decay. Pyrite decay can be slowed by ensuring specimens of marcasite are kept at less than sixty percent humidity. Despite this failing, gem quality iron pyrite is still referred to as marcasite in the jewellery world and the material is making a comeback. This is from an article concerning a seminar held in India reported in the jewellery trade publication Diamond World:

Cubic Crystallisation by Ornella Iannuzzi. Pyrite set in black & gold rhodium
Image by Simon Armitt

On The Rock by Ornella Iannuzzi. Pyrite and matrix set in vermeil
Image by Simon Armitt

Magnum Opus in Crucible by Ornella Iannuzzi. Pyritohedral Pyrite set in silver
Image by Simon Chapman

Folklore and Medicine

The civilisations of Meso-America (Aztec, Inca, Mayan, etc.) were renowned for polishing large slabs of pyrite to employ as mirrors which could be used in scrying, or crystal gazing, the magical practice of divining the course of future events by the power contained within crystals.

Native North American tribes also employed pyrite as mirrors, in ceremonies and for medicinal purposes, and believed that by peering into polished specimens they could see into a person’s soul.

The Ancient Chinese deemed that pyrite would guard against crocodile attack. In addition, they viewed the Earth as being a golden cube, a form which pyrite reproduces perfectly.

A new-age movement with a belief in the innate power of crystals, like the alchemists and magicians who preceded them, imbue pyrite with a number of useful qualities. The following is taken from a web page on The Metaphysical and Healing Properties of Minerals:

Pyrite is also thought to enhance the flow of energy between right and left brain hemispheres and protect against any number of infections and illnesses. It assists one in seeing behind the façades of others and promotes an understanding of that which lies beneath words and actions. It can be used to stimulate the powers of the intellect, enhancing memory and providing for recall of relevant information, when required. Pyrite also encourages and sustains the flawless ideal of health, intellect, and emotional well-being. It symbolized the warmth and lasting presence of the sun and promotes the recall of beautiful memories of love and friendship.

Medicinally, pyrite became known as the Healer’s Stone, and it is thought to offer physical aid in treating a wide range of afflictions including infections, viruses and fevers, blood disorders, it increases blood flow to the brain and improves circulatory system, increases memory, bone and cellular formation, helps fatigue, lung problems, digestive tract problems, relieves anxiety and stress.

Pyrite in the Tees Valley

Locally, pyrite may be found in several rock units of Jurassic age, most commonly within Lower Jurassic (Lias Group) strata. The Redcar Mudstone Formation contains a unit dubbed the Pyritous Shale, within which pyrite is commonly found as a replacement mineral in fossil specimens.

The Whitby Mudstone Formation (formerly Upper Lias) is perhaps most noted for the presence of pyrite locally. The formation is divided into three broad informal units, the Grey Shale, Bituminous Shale, and Alum Shale Members. Aggregates of several centimetres, and octahedral crystals can be found locally within the Bituminous Shale around Port Mulgrave, Runswick, Kettleness, and Sandsend. In spite of the presence of much pyrite in the scar nearby, it seems that the village of Goldsborough derives its name from Norse roots, viz.; “the burgh (fortified manor or hill) belonging to Golda”.

Octahedral pyrite (outlined) in the scar at Rosedale Wyke, Port Mulgrave, North Yorkshire.

The Alum Shale Member also contains pyrite, though it is generally less visible being present in the form of framboidal aggregates. These comprise many tiny spherical masses of pyrite particles produced through the action of pyrite-producing bacteria which ‘fed’ on iron and ferrous sulphate ions in the unconsolidated sediment. Pyrite’s presence was essential to the success of the local alum trade, assisting in the alum making process. During calcination (heating) of the quarried shale, iron di-sulphide is broken down via an exothermic reaction which increases the overall heat involved. Some of the sulphur is lost as sulphur dioxide, the remainder takes part in reactions which eventually form sulphuric acid and ferrous sulphate. Sulphuric acid, in turn, breaks down the alumino-silicates within the shale, rendering them soluble and available to recrystallise into alum.


The Cleveland Ironstone Formation locally contains pyrite. In the East Cleveland area, around Skelton, a thin bed of pyritous material, dubbed the Sulphur Band, caps the Main Seam. This was occasionally recovered and sent to Teesside to be used by the growing chemical industry in the production of synthetic sulphuric acid.

Following abandonment of the ore-field, in the 1960s, pumping of the ironstone mines was curtailed causing them to gradually fill with water. Contact with water encourages the breakdown of both siderite (FeCO₃) and pyrite, the mine-water becomes saturated and on exposure to air precipitates ochreous iron oxide imparting a bright orange-red colour. This has caused severe problems in the area, not least at Eston and New Marske. The beck running through Skinningrove was formerly heavily polluted. So much so that the area became known locally as Red-River Valley for many years until filtration to remove the pollutant was employed. Saltburn Beck, running through Saltburn Gill, has been suffering from mine-water pollution for many years, since ochreous water burst out of workings connected with the former Longacres Mine near Skelton. Ochreous iron oxide has smothered life in the stream which will (however) recover naturally once the pollution is successfully dealt with.

The source of mine-water pollution above Saltburn Gill, Cleveland.

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

Grid Reference NZ 7784 192
BGS Sheet 34
OS Sheet 94
Forwarded as RIGS Part of Skinningrove to Staithes Coast 30/09/2003

Site Description

Site Status Part of the Heritage Coast
Description of Geodiversity Costal cliff nab exposure consisting of the Staithes sandstone formation which is the type locality. The foreshore to the west of the coastal defences consists of Redcar mudstone
Literature References The Yorkshire Coast – Peter Rawson & John Wright 1992
The Regional Coastline of Yorkshire – J.W.Steers 1967

Site Map

Site Assessment

Surveyors

Andrew Carter, Andrew Cooper, Carl Rees-Davies

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

Grid Reference NZ 690 228
BGS Sheet 34
OS Sheet 94
Forwarded as RIGS Part of Saltburn to Skinningrove Coast 30/09/2003

Site Description

Site Status SNCI
Description of Geodiversity Wave washed platform and cliffs revealing Redcar mudstone formation at the base overlain by Staithes sandstone in the cliffs. Cleveland ironstone in upper part of cliffs, all capped by glacial till
Literature References Along the Scar – Denis Goldring 2001
The Regional Coastline of Yorkshire – J.W.Steers 1967

Site Map

Site Assessment

Surveyors

Denis Goldring

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

Grid Reference NZ 615 253
BGS Sheet 34
OS Sheet 93
Forwarded as RIGS 30/09/2003

Site Description

Site Status SSSI
Description of Geodiversity Wave washed platform of Redcar mudstone. Locality reveals the lowest Lias group exposure in the Tees Valley
Literature References Along the Scar – Dennis Goldring 2001
The Regional Coastline of Yorkshire – J.W.Steers 1967

Site Map

Site Assessment

Surveyors

Andrew Carter, John Waring

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

Grid Reference NZ 610 260
BGS Sheet 34
OS Sheet 93
Forwarded as RIGS 30/09/2003

Site Description

Site Status SNCI
Description of Geodiversity Wave washed platform of Redcar mudstone with small exposure of overlying Staithes sandstone exposed at low tide
Literature References Along the Scar – Denis Goldring 2001
The Regional Coastline of Yorkshire – J.W.Steers 1967

Site Map

Site Assessment

Surveyors

Andrew Carter, John Waring

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 715 201 to 745 202
BGS Sheet: 34
OS Sheet: 94
Forwarded as RIGS: 30/09/2003

Site Status: Heritage Coast (RC4, other references Nos. 51 and 82). Open access.

Description of Geodiversity: Superb sea cliffs and rocky foreshore (scar) with extensive Lias Group exposures. Much geomorphological and industrial archaeological interest. The Cleveland Way passes along the cliff top. The coastal scenery is impressive.

Members of the RIGS Group and others on an outing near Hummersea steps, showing Hummersea Cliff extending westward toward Skinningrove. Huntcliff is shown in the background. The group are standing on an area of slam, a by-product of the alum-making process.

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.

• Cleveland Ironstone and Staithes Sandstone Formations: These form the main cliff faces. The ironstone seams of the Cleveland Ironstone Formation can be examined directly as a result of the landslip at the Old Gut (other reference no. 80).
• 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).

Image of the so-called Cannon-ball Doggers of the Redcar Mudstone Formation between Skinningrove and Hummersea steps. Nodules are c.5cm in diameter.

Geomorphology: Apart from the marine and sub-aerial erosion of the cliffs there are a number of interesting features particularly the U-shaped, till-infilled embayment at Hummersea and the landslip at the Old Gut. Hummersea Beach has a marvelous variety of glacially-derived pebbles to examine.

Historical geology: No specific comments.

Industrial Archaeology:

• The cliffs form the seawards edge of Main Seam (Cleveland Ironstone Formation) underground workings of Loftus Ironstone Mine.
• With regard to the alum industry, the remains of the Loftus alum house and landing place (dock) are at the New Gut (NZ 726 200) and an earlier dock (and possibly the site of an alum house) at the Old Gut (NZ 734 202).

Access

Access map of the area around Hummersea showing the Cleveland Way and suggested parking in Skinningrove.
(Click on map to enlage)

Access can be gained:

1. From the east side of Skinningrove Beck mouth along the cliff foot, or
2. By the path and ladder down to Hummersea Beach and the New Gut from the Cleveland Way.

General Assessment

This coast is an excellent place for the study of Lower Jurassic geology, geomorphology and industrial archaeology for all age groups.

Associated Sites

Boulby Alum Quarries (SSSI, other reference no. 54);
Loftus Alum Quarries (SSSI, other reference no. 53);
Boulby and Cowbar Nab Cliffs ((RC5, other reference no. 80);
Old Gut Landslip (other reference no. 82).

The view east showing the cliffs and foreshore toward Loftus Alum Quarry from the top of Hummersea steps.

Safety Information

WARNING: If going along the scar it is imperative to be aware of the tide times and the sea conditions. The scar is likely to be wet and slippery and there is danger of falling rock from the unstable cliffs. A boulder field makes going east beyond the Old Gut difficult and further easterly progress should be avoided.

BE AWARE: Hummersea steps may occasionally be in a state of disrepair, we suggest you ensure that the state of the steps is known prior to setting off on any walk along the scar. There is no other way up the cliff between Skinningrove and Staithes posing the danger of being cut off by the tide if the steps are impassable.

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 sketch cross-section illustrates the geology. The dip is 1-in-16 to the south at Hummersea Point but gradually lessens and changes direction to the SSW eastwards. A minor fault about 75m east of Hummersea Point trends N-S and throws a few cm to the east. However, in the mine workings to the south the throw is recorded as 4m. Another small fault occurs at the Old Gut.

Section through Hummersea Point and Warsett Hill demonstrating dip of beds to the south at c.1-in-16.

Whitby Mudstone Formation (marine, in part anoxic): The Hard and Mulgrave Shale Members are present high up in the cliffs east of Hummersea steps. 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 at Hummersea Point and, again, beyond Hummersea Beach above the Old Gut. The seams can be examined directly where they are preserved intact as if in-situ and nearly vertically disposed as a result of the landslip at the Old Gut. The section here was measured by Barrow (1888, page 19).

Staithes Sandstone Formation (shallow marine, with tidal influences and storm surges): Again, the beds can be seen in the cliff face and examined by means of fallen blocks.

Redcar Mudstone Formation (marine): The base of the Oyster Bed, seen in the cliff face, marks the arbitrarily defined top of the Ironstone Shale (the upper subunit of this Formation) although the sequence is transitional. Around 20m of the Ironstone Shale are exposed on the scar. Tate and Blake (1876, pages 94-96) give their measured section but this is difficult to interpret. The section includes ~12m of the Staithes Sandstone Formation (including the Starfish beds) and only ~5m of the Redcar Mudstone Formation, said to be down to the cliff base. Hence, it must have been measured somewhere where the cliff was accessible. It includes a substantial fossil list. So far as is known, there is no modern lithic log, the nearest being at Staithes.

View looking west from the Cleveland Way above Skinningrove showing beach defences, the jetty, Huntcliff and Warsett Hill in the background.

Geomorphology: Skinningrove Beck has cut a deep channel through the till into the bedrock. Eastwards for about 1km, passing Hummersea Point, sub-vertical cliffs 50 to 70m high are capped by some till. There are two deep ravines, structurally controlled by small faults and major joints, with intensive sub-aerial erosion.

Hummersea Beach is currently a superb pebble beach with a wide variety of petrological types derived from the till (or may be some ship’s ballast) and including Shap Granite. However, local residents say that it was once sandy and there are photos showing this. To the south there is a curious U-shaped, 0.5km-wide embayment in the cliff line with bedrock at c.15m, much till infill and recent landslips. The origin of this and the similar feature at Port Mulgrave is unclear. They may be the result of:

1. Pre-glacial scarp retreat (with landslipping)
2. Glaciation, or
3. Interglacial marine erosion.

Beyond Hummersea Beach there is a return to high cliffs, now without glacial cover. These continue eastwards below Loftus and Boulby Alum Quarries. There are some substantial landslips and rock falls including the remarkable slip at the Old Gut.

Historical geology: No specific comments.

Industrial History and Archaeology

Alum: 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) as well as descriptions by Buglass (2002) and Miller (2002).

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 with a dock at the New Gut. The dock was previously at the Old Gut and the earlier alum house was probably close by, either at the cliff top or at beach level. There are indications of a track down to the beach at this point.

The outstanding remaining feature at Hummersea Beach by the modern steps is the stone-built ‘kiln’, believed to have been used for calcining cementstone nodules. Other remains, particularly the brick-lined ‘flues’ to the east have been eroded rapidly in recent years (comparison can be made with photos in Buglass (ibid) and Miller (ibid). The back, in-situ rock wall of the excavation made for them has now come in to view.

The New Gut is bordered on both sides by ‘rafts of mixed beach pebble and alum waste (slam). The Ordnance Survey shows several postholes but these may be difficult to find.

View of the alum works remains in the cliff-side near Hummersea steps.

The Old Gut has the remains of a stone built jetty alongside part of which actually consists of the in situ landslip material including the Main Seam. There are post holes and, as recorded by Owen (1986) and Buglass (ibid), signs of a short tramway. Owen recorded another tramway 300m to the east (NZ 737 202).

Beyond, to the east, there is a third dock with postholes (NZ 7461 2015) that is difficult to reach (Buglass (ibid), page 137, site 7 and Hunt et al., 2004, page 49).

Ironstone: The Main Seam of the Cleveland Ironstone Formation has been worked extensively 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 first major underground ironstone mine to be developed in North Cleveland. Mining started in 1848, two years before Eston but 12 years after the mines at Grosmont. The seam 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.
The workings, daylighting in the cliff face, can be seen clearly from the scar, especially at the Old Gut.
There was some earlier ironstone working involving the collection of material from the beaches.

Rutways and Tramways: Owen (1986) identified a number of rutways especially in the vicinity of Hummersea Point (see also Buglass ibid. Site 3, page 135). Owen also recorded the tramways at and beyond the Old Gut.

Members of the RIGS Group examine a rutway (shown by arrows) between Skinningrove and Hummersea steps.

Literature References

Maps

Geological Survey Yorkshire Sheet IX SW, scale 6 inches to 1 mile, 1878 (Ordnance Survey 1856).
As well as the geology, this shows the landing places (docks) at the Old and New Guts, an outline plan of the alum house at the New Gut and some other buildings close to the beach.

Excursion Guides

Goldring, D. 2010. Guided Walk to Loftus Alum Works 11th July, 2009. CIAS Newsletter No. 98, March 2010, 9-14.

Goldring, D. 2001. Along the Scar. Peter Tuffs, Guisborough, 145p. See pages 53-58.

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. The Main Seam ironstone section at the Old Gut is on page 19.

Fox-Strangways, C. 1892. The Jurassic Rocks of Britain Mem. 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.

Tate, R. and Blake, J. F. 1876. The Yorkshire Lias. John Van Voorst, London, 475p.
Pages 89-101, especially pages 94-96 with a measured section at Hummersea.

Industrial History & Archaeology

Alum

Buglass, J. 2002. A survey of coastal transport in the alum industry with reference to Hole Wyke and New Gut Docks. Chapter 8 and Appendix 4 in ed. I. Miller, ‘Steeped in History. The alum industry of North-East Yorkshire’. NorthYorks Moors National Park Authority. 89-106, 135-138.
Report on survey made in 2000 with pictures enabling one to assess the extent of erosion of manmade and landslipped material at Hummersea beach.

Hunt, A. et al. 2004. Loftus Alum Works, Redcar and Cleveland, Cleveland. An archaeological and historical survey. English Heritage, 67pp.
A major survey including the foreshore features.

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

Chapman, S. 1998. The Loftus Mines, Skinningrove. Peter Tuffs Publications, 100pp.
A detailed account of Loftus Mines.

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

Mini Geo-trail

Click here to go to the Mini Geo-Trail » (Soon to be available as a PDF).

Surveyors

Denis Goldring 2011

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