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 19th 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-17th to late-18th century and late-18th to late-19th 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 19th 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.
