The BGS Lexicon of Named Rock Units — Result Details

Upper Lias [Obsolete Name And Code: See WHM]

Computer Code: ULI Preferred Map Code: notEntered
Status Code: Index Level
Age range: Pliensbachian Age (JE) — Toarcian Age (JT)
Lithological Description: Mudstones, siltstones and sandstones with limestone nodules and, locally, limestone beds at base.
Definition of Lower Boundary: Base Toarcian, or base of Toarcian argillaceous/arenaceous rocks resting on calcareous ferruginous Upper Pliensbachian to Lowar Toarcian strata. See notes under "Geographical Limits".
Definition of Upper Boundary: Top Toarcian, or top of argillaceous/arenaceous strata (Toarcian to, locally, Aalenian) succeeded by calcareous (limestone) and arenaceous strata of the Inferior Oolite Group or Dogger Formation. See notes under "Geographical limits".
Thickness: Unspecified
Geographical Limits: The term was used loosely to signify the upper, argillaceous/arenaceous part of the Lower Jurassic succession now known as the Lias Group.. It has commonly been used in a chronostratigraphical rather than lithostratigraphical sense tp mean "Toarcian strata".
Parent Unit: Not Entered (?)
Previous Name(s): none recorded or not applicable
Alternative Name(s): Whitby Mudstone Formation
Stratotypes:
none recorded or not applicable
Reference(s):
Cox, B M, Sumbler, M G and Ivimey-Cook, H C, 1999. A Formational framework for the Lower Jurassic of England and Wales (Onshore Area). British Geological Survey Research Report No. RR/99/01. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E184 E216 E064 E072 E114 E127 E143 E144 E157 E158 E159 E170 E171 E172 E185 E186 E187 E201 E202 E204 E217 E218 E220 E235 E236 E251 E252 E253 E264 E265 E279 E280