The BGS Lexicon of Named Rock Units — Result Details

Sandwick Member

Computer Code: SWIK Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Arundian Substage (CJ)
Lithological Description: Limestone, with interbedded subordinate claystone and siltstone. Limestones are packstone and wackestone, grey, bioclastic including crinoids and corals, bioturbated, sharp based, graded beds with hummocky cross bedding. Claystones and siltstones are grey, bioclastic, forming thin, discontinuous beds. Interpreted as a mid-ramp carbonate facies with limestones representing storm deposits and mudstones quiet water conditions. The member represents a period of maximum flooding.
Definition of Lower Boundary: The base of the Sandwick Member is poorly defined. It is poorly exposed on the foreshore at Derbyhaven [SC 2835 6653] where it overlies the Turkeyland Member. The boundary is gradational, taken at the change from limestone (Turkeyland Member) to limestone with interbedded claystones (Sandwick Member).
Definition of Upper Boundary: The top of the member is poorly defined. It is overlain by limestones, sandstones and siltstones of the Skillicore Member, with a gradational contact, taken at the appearance and increasing occurrence of fine-grained sandstone, together with an increase in siltstone and a more tabular bedding style.
Thickness: c.46m
Geographical Limits: Southern part of the Isle of Man, in the area east of Castletown, from [SC 2970 6913] to [SC 2822 6677].
Parent Unit: Derbyhaven Formation (DBH)
Previous Name(s): Ronaldsway Member (-3063)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Discontinuous outcrops of the lower part of the Sandwick Member succession are exposed on the foreshore east of Ronaldsway Farm [SC 2924 6822] to [SC 2941 6859] Dickson et al. (1987) 
Partial Type Section  Natural foreshore exposures to the south-south-east of Derbyhaven [SC 2827 6699]. Discontinuous poorly exposed outcrops are present through the lower half of the member Dickson et al.(1987) 
Reference(s):
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. 
Lamplugh G W. 1903. The geology of the Isle of Man. Memoir Geological Survey of Great Britain 
Dickson, J A D, Ford, T D and Swift, A. 1987. The stratigraphy of the Carboniferous rocks around Castletown, Isle of Man. Proceedings of the Yorkshire Geological Society, Vol.46, 203-229. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E400