The BGS Lexicon of Named Rock Units — Result Details

Yoredale Group

Computer Code: YORE Preferred Map Code: notEntered
Status Code: Full
Age range: Holkerian Substage (CQ) — Yeadonian Substage (CY)
Lithological Description: The Yoredale Group (mixed shelf carbonate and deltaic (Yoredale) facies and fluviodeltaic (Millstone Grit) facies) extends across the entire Northern England province and comprises: In the Northumberland Trough and Solway Basin, the Tyne Limestone, Alston and Stainmore formations; In the Alston Block, Stainmore Trough and Askrigg Block, the Alston and Stainmore formations; In north Cumbria, the Alston Formation; In south Cumbria (and north Lancashire), the Alston Formation; In west Cumbria, the Stainmore Formation; In the north Isle of Man, a sequence similar to the Alston Formation, and another apparently assigned to either the Great Scar Limestone Group or Yoredale Group. These are known only in boreholes (see Chadwick et al., 2001); In the Southern Uplands of Scotland, the Yoredale Group is restricted to the Thornhill Basin, with a single formation, the Closeburn Limestone Formation. The Yoredale Group comprises repeated, typically upwardcoarsening cycles of basal, laterally extensive marine limestone, marine shale (commonly bioturbated), thin sandstone commonly topped with seatearth or ganister and an overlying coal. The limestones are typically mid to dark grey, thin-bedded and biomicritic, with a restricted benthic fauna and rare ammonoids. The sandstones are typically pale grey, fine- to medium-grained and quartzitic to subarkosic. The clastic component was deposited by progradation of high-constructive lobate deltas, though there is evidence to suggest that there has been extensive shallow marine reworking of clastic sediments following delta abandonment (Elliott, 1975). Large fluvial channels were incised into underlying cyclothems on the Alston Block during the Brigantian and Pendleian (Dunham, 1990), and in Northumberland an element of tectonic control on this process can be demonstrated (Young and Lawrence, 2002). The marine limestones were deposited during sea-level rises and when delta lobes were switched or abandoned. The cycles, which range from 5-90 m thick, are named after the limestone present at the base of the cyclothem (Leeder et al., 1989). Limestones have bed status unless there are good reasons for them to have member status. Minor limestones and sandstones remain informal beds. Dunham and Wilson (1985) provided details of limestone nomenclature and correlations, and cyclothem thicknesses for the Askrigg Block and Stainmore Trough, and Dunham (1990) provided similar information for the Alston Block. On the north Isle of Man undifferentiated strata assigned to either the Great Scar Limestone Group or the Yoredale Group occurs in the Ballavaarkish (Shellag North) Borehole [NX 4625 0070] between 172.34 and 179.60 m depth. They comprise massive, stylolitised, fractured and sucrosic dolostone, which may be of early Namurian or Visean age, but diagenesis has destroyed any biostratigraphical evidence (see Chadwick et al. 2001).
Definition of Lower Boundary: The conformable but diachronous base of the Yoredale Group is typically taken at the base of marine limestone marker bands. In the Solway Basin, Northumberland Trough, Cheviot Block and north-east Northumberland, the sandstones of the Fell Sandstone Formation, Border Group pass upward, locally unconformably and diachronously, into the Tyne Limestone Formation, Yoredale Group; the lower boundary of which is variably represented as the base of the Clattering Band or its correlative the Kingsbridge Limestone, or in the Langholm area, the Glencartholm Volcanic Beds. In the Brough-under-Stainmore and Penrith districts the Robinson Limestone of the Melmerby Scar Limestone Formation, Great Scar Limestone Group, is overlain by siltstone or sandstone of the Tyne Limestone Formation, Yoredale Group. There is evidence of penecontemporaneous erosion and potholing on the top surface of the Robinson Limestone. In east Cumbria and the Stainmore Trough, the lower boundary of the Yoredale Group occurs where the top of the mostly thick-bedded, pale to mid grey limestone of the Knipe Scar Limestone Formation, Great Scar Limestone Group, is disconformably overlain by the variable sandstone and mudstone Wintertarn Sandstone Member of the Tyne Limestone Formation. On the northern Askrigg Block, the pale to mid grey limestones (with palaeokarst surfaces) and subordinate mudstones of the Danny Bridge Limestone Formation, Great Scar Limestone Group pass upward into the crossbedded, regressive sandstones of the Wintertarn Sandstone Member, Tyne Limestone Formation. In the Settle area, the lower boundary of the Yoredale Group is generally taken where the paler grey, thick- to very thick-bedded limestone with palaeokarst surfaces of the Malham Formation, Great Scar Limestone Group pass upward into the darker grey Lower Hawes Limestone (Alston Formation) at the base of the Yoredale facies sequence. In west Cumbria, in the Egremont-Whitehaven-Maryport-Cockermouth area, the lower boundary of the Yoredale Group occurs where the shelf carbonate sequence of the First Limestone, Eskett Limestone Formation is terminated and conformably overlain by the mostly clastic marine and deltaic facies of the Stainmore Formation. However, at outcrop the basal part of the Stainmore Formation generally comprises the coarse-grained, fluvial, Hensingham Grit, with a basal mudstone. In north Cumbria, east of the Bothel Fault, the lower boundary of the Yoredale Group occurs above the pale to dark grey limestones of the Eskett Limestone Formation, Great Scar Limestone Group, at the top of the White Limestone unit, which forms the base of the Fourth Limestone. Immediately west of the Bothel Fault, however, the same boundary occurs at the top of the Fourth Limestone, which is distinguished by the inclusion of palaeokarst surfaces and distinctive fossils. It should be stressed that division east and west of the Bothel Fault is purely for ease of description. The Bothel Fault is not implied to have exerted any penecontemporaneous effects on deposition. In south Cumbria, the lower boundary of the Yoredale Group is at the point where the predominantly pale grey, thickly bedded limestones of the Urswick Formation, Great Scar Limestone Group, pass up into the predominantly dark grey, thinner bedded limestones and mudstones of the Alston Formation. On the northern part of the Isle of Man, platform carbonates of the Balladoole Formation, Great Scar Limestone Group are thought to be overlain by a cyclothemic mixed carbonate clastic sequence, similar to the Alston Formation, Yoredale Group of south Cumbria.
Definition of Upper Boundary: The top of the Yoredale Group is defined in north, west and east Cumbria, the Solway Basin, the Stainmore and Northumberland troughs, on the Alston Block and in north-east Northumberland by the base of the Pennine Coal Measures Group (fluviodeltaic (Coal Measures) facies). To the north of Wensleydale on the Askrigg Block and in the Settle area, it is defined by the base of the Millstone Grit Group (fluviodeltaic (Millstone Grit) facies). On the northern part of the Isle of Man the top of what may be either the Great Scar Limestone Group or the Yoredale Group is also defined by the base of the Millstone Grit Group. In south Cumbria the base of the Craven Group (hemipelagic facies) defines the top of the Yoredale Group.
Thickness: Thickness varies greatly since the group, formations and individual sandstones tend to thicken into troughs and halfgrabens, and conversely all the elements of any rhythm may be reduced or absent. The range in thickness is from 50 m in the Lamplugh area of west Cumbria (Young and Bolland, 1992) to a proved maximum of 1219 m in the Seal Sands Borehole (BGS Registration Number NZ52SW/457) [NZ 538 238] in the eastern part of the Stainmore Trough (Dunham and Wilson, 1985). In south Cumbria the group is 80-180 m thick, and over 500 m of strata are present in the Solway Basin in boreholes north of Maryport. On the Askrigg Block, generalised vertical sections on BGS maps suggest a range of thickness in the order of about 200-900 m, and there are marked thickness variations across the Stublick-Ninety Fathom Fault, separating the Northumberland Trough from the Alston Block, to the south.
Geographical Limits: The type area of the Yoredale Group is the valley of the River Ure, Wensleydale on the Askrigg Block (see Phillips, 1836; George et al., 1976; Dunham and Wilson, 1985), and it extends across the entire Northern England Province. In the Southern Uplands of Scotland, the Yoredale Group is restricted to the Thornhill Basin.
Parent Unit: Not Applicable (-)
Previous Name(s): Liddesdale Group (in part) [Obsolete Name and Code: Use YORE] (-1292)
Wensleydale Group [Obsolete Name and Code: Use YORE] (WND)
Yoredale Beds (Undifferentiated) [Obsolete Name and Code: Use YORE] (YB)
Yoredale Beds [Obsolete Name and Code: Use YORE] (YOB)
Liddesdale Group [Obsolete Name and Code: Use YORE] (LDD)
Alternative Name(s): none recorded or not applicable
Stratotypes:
none recorded or not applicable
Reference(s):
Dean, M T, Browne, M A E, Waters, C N and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report, RR/10/007. 165pp. 
Waters, C N, Gillespie, M R, Smith, K, Auton, C A, Floyd, J D, Leslie, A G, Millward, D, Mitchell, W I, McMillan, A A, Stone, P, Barron, A J M, Dean, M T, Hopson, P M, Krabbendam, M, Browne, M A E, Stephenson, D, Akhurst, M C, and Barnes, R P. 2007. Stratigraphical Chart of the United Kingdom: Northern Britain. (British Geological Survey.) 
Chadwick, R A, Jackson, D I, Barnes, R P, Kimbell, G S, Johnson, H, Chiverell, R C, Thomas, G S P, Jones, N S, Riley, N J, Pickett, E A, Young, B, Holliday, D W, Ball, D F, Molyneux, S G, Long, D, Power, G M and Roberts, D H. 2001. Geology of the Isle of Man and its offshore area. British Geological Survey Research Report, RR/01/06. 
Elliott, T. 1975. The sedimentary history of a delta lobe from a Yoredale (Carboniferous) cyclothem. Proceedings of the Yorkshire Geological Society 40, 505-536. 
Dunham, K C. 1990. Geology of the Northern Pennine Orefield, Vol.1. Tyne to Stainmore, (2nd edition) Economic Memoir of the British Geological Survey, Sheets 19 and 25, parts of 13, 24, 26, 31, 32 (England and Wales). 
Young, B, and Lawrence, D J D. 2002. Geology of the Morpeth district. A brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50 000 Sheet 14 Morpeth (England and Wales). 
Leeder, M R, Fairhead, D, Lee, A, Stuart, G, Clemmey, H, El-Haddaheh, B and Green, C. 1989. Sedimentary and tectonic evolution of the Northumberland Basin. Proceedings of the Yorkshire Geological Society 47, 207-223. 
Dunham, K C, and Wilson, A A. 1985. Geology of the Northern Pennine Orefield. Volume 2 Stainmore to Craven. Economic Memoir of the British Geological Survey, Sheets 40, 41 and 50, and parts of Sheets 31, 32, 51, 60 and 61(England and Wales). 
Phillips, J. 1836. Illustrations of the Geology of Yorkshire, Part II. The Mountain Limestone District. (London:John Murray). 
George, T N, Johnson, G A L, Mitchell, M, Prentice, J E, Ramsbottam, W H C, Sevastopulo, G D and Wilson, R B. 1976. A correlation of the Dinantian rocks of the British Isles. Special Report of the Geological Society of London, No 7. 
Akhurst, M C, Chadwick, R A, Holliday, D W, McCormac, M, McMillan, A A, Millward, D, Young, B, Ambrose, K, Auton, C A, Barclay, W J, Barnes, R P, Beddoe-Stephens, B, James, J C W, Johnson, H, Jones, N S, Glover, B W, Hawkins, M P, Kimbell, G S, MacPherson, K A T, Merritt, J W, Milodowski, A E, Riley, N J, Robins, N S, Stone, P, and Wingfield, R T R. 1997. The geology of the west Cumbria district. Memoir of the British Geological Survey, Sheets 28, 37 and 47 (England and Wales). 138pp. 
Johnson, G A L, Hodge, B L and Fairbairn, R A. 1962. The base of the Namurian and the Millstone Grit in northeast England. Proceedings of the Yorkshire Geological Society, Vol.33, 341-362. 
Young, B and Boland, M P. 1992. Geology and land-use planning: Great Broughton-Lamplugh area, Cumbria. BGS Technical Report WA/92/54. 
Waters, C N, Browne, M A E, Dean, M T and Powell, J H. 2007. Lithostratigraphical framework for Carboniferous successions of Great Britain (Onshore). British Geological Survey Research Report, RR/07/01. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E049