The BGS Lexicon of Named Rock Units — Result Details

Glencartholm Volcanic Member

Computer Code: GV Preferred Map Code: GV
Status Code: Full
Age range: Holkerian Substage (CQ) — Asbian Substage (CR)
Lithological Description: Tuff and localised basalt lavas, with interbedded mudstone, sandstone and thin limestone. These volcanic beds are distinguished by the presence of tuffaceous sedimentary rocks, mainly sandstones with varying proportions of volcanic debris.
Definition of Lower Boundary: A conformable boundary upon sedimentary rocks, mainly sandstone, of the Fell Sandstone Formation. Volcanic debris is absent in the underlying sandstones of the Fell Sandstone Formation.
Definition of Upper Boundary: Conformable boundary with the sandstone and mudstone of the Tyne Limestone Formation. The top of the unit is taken at the top of the highest tuffaceous sandstone.
Thickness: From 150m to 180m
Geographical Limits: Not recorded. Section on the left bank of the River Esk continued from stratotype: "Because there is no continuous sequence and because the strata are poorly bedded and faulted, the total thickness is difficult to assess. The strata dip owards the south or southeast at between 5 and 60 degrees. The lowest beds of blue grey tuffs and tuffaceous sandstones, which outcrop for about 165m downstream of the Mumbie Fault, are in excess of 21m thick. These beds are overlain by interbedded tuffs, tuffaceous sandstones, siltstones and cementstones with numerous beds of chert, cherty sandstone and limestone. Some of these beds are richly fossiliferous (Peach and Horne, 1903). The top of the Glencartholm Volcanic Beds, comprising a strike section of bluish and greenish grey bedded tuffs and tuffaceous mudstone is seen in Heck's Burn at NY 3821 7974." Scattered outcrops are present from Annandale (NY 317000 573000) to east of Langholm (NY 345000 583000).
Parent Unit: Tyne Limestone Formation (TYLS)
Previous Name(s): Glencartholm Volcanic Group (-944)
Glencartholm Volcanic Beds (-2220)
Alternative Name(s): none recorded or not applicable
Reference Section  Archerbeck Borehole, Langholm, NY47NW/14 (on Sheet S11), from 1303.6m to 1403.3m depth (TD). Lumsden and Wilson, 1961; Lumsden et al., 1967. The strata comprise interbedded tuffaceous sandstones, siltstones and mudstones. 
Type Section  Section on the left bank facing downstream, of the River Esk, at Glencartholm, 5km south of Langholm, between the Heck's Burn and Mumbie faults, upstream from the mouth of Heck's Burn. See "Geographical Limits" Description for fuller details. Also, Lumsden et al., 1967. 
Peach, B N and Horne, J .1903. The Canonbie coalfield: its geological structure and relations to the Carboniferous rocks of the north of England and central Scotland. Transactions of the Royal Society Edinburgh, 40, 835-77. 
Lumsden G I and Wilson R B. 1961. The stratigraphy of the Archerbeck Borehole, Canonbie Dumfriesshire. Bulletin of the Geological Survey of Great Britain, No.18, 1-89. 
Lumsden G I, Tulloch W, Howells M F and Davies A. 1967. The geology of the neighbourhood of Langholm. Memoir of the Geological Survey, Sheet 11 (Scotland). 
Stephenson, D, Loughlin, S C, Millward, D, Waters, C N and Williamson, I. 2003. Carboniferous and Permian igneous rocks of Great Britain, north of the Variscan Front. Geological Conservation Review Volume 27. Joint Nature Conservation Committee: Peterborough. 374 pp. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S011 S010