The BGS Lexicon of Named Rock Units — Result Details

Lady's Walk Formation [See Also LAWA]

Computer Code: LDYW Preferred Map Code: notEntered
Status Code: Full, pending ratification
Age range: Sinemurian Age (JS) — Pliensbachian Age (JE)
Lithological Description: The formation comprises dark to medium grey, calcareous, micaceous, shelly mudstone. Upward-fining sandstone-siltstone units, with burrowed bases, occur.
Definition of Lower Boundary: The lower boundary is marked by a downward change from dark, fossiliferous mudstone to white to pale grey sandstones with interbedded mudstone (Mains Formation), and a marked down-section decrease in average gamma-ray values and an increase in velocity.
Definition of Upper Boundary: The upper boundary is placed between an upward-coarsening siltstone-sandstone unit (Orrin Formation) and mudstone (Lady's Walk Formation). The boundary corresponds to the top of a low velocity spike. Where the Orrin Formation is absent, the upper boundary is placed at a downward change from sandstone (Beatrice Formation) to shelly mudstone, or sandstone and mudstone (Brora Coal Formation) to shelly mudstone.
Thickness: Up to 30 m.
Geographical Limits: Inner Moray Firth Basin, North Sea UK Quadrants 11, 12, 17, 18.
Parent Unit: Dunrobin Bay Group [See Also DRB] (DUNR)
Previous Name(s): Dronach Shale Member (-5107)
Lady's Walk Shale Unit (-5108)
Alternative Name(s): Lady's Walk Shale Member [See Also LDYW]
Stratotypes:
Type Section  North Sea well 11/30-4 at 2276.5-2305.5 m depth below KB. Richards et al. (1993). 
Reference Section  North Sea well 12/21-2 at 2339-2363.5 m depth. Richards et al. (1993). 
Reference Section  North Sea well 12/27-2 at 1628.5-1653.5 m depth. Richards et al. (1993). 
Reference(s):
Andrews, I J and Brown, S. 1987. Stratigraphic evolution of the Jurassic, Moray Firth. In: Brooks, J and Glennie, K W (eds.) Petroleum Geology of North West Europe, 785-795. [Graham & Trotman, London] 
Stevens, V. 1991. The Beatrice Field, Block 11/30a, UK North Sea. In: Abbotts, I L (ed.) United Kingdom oil and gas fields 25 years commemorative volume. Memoir of the Geological Society, London, 14, 245-252. 
Richards, P C, Lott, G K, Johnson, H, Knox, R W O'B. and Riding, J B. 1993. 3. Jurassic of the Central and Northern North Sea. In: Knox, R W O'B and Cordey, W G. Lithostratigraphic nomenclature of the UK North Sea. [British Geological Survey, Nottingham] 
Batten, D J, Trewin, N H and Tudhope, A W, 1986. The Triassic-Jurassic junction at Golspie, Inner Moray Firth Basin. Scottish Journal of Geology, Vol.22, part 1, 85-98. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable