The BGS Lexicon of Named Rock Units — Result Details


Computer Code: HEAD Preferred Map Code: symb
Status Code: Full
Age range: Quaternary Period (Q) — Quaternary Period (Q)
Lithological Description: Head is poorly sorted and poorly stratified, angular rock debris and/or clayey hillwash and soil creep, mantling a hillslope and deposited by solifluction and gelifluction processes. Solifluction is the slow viscous downslope flow of waterlogged soil and other unsorted and unsaturated superficial deposits. The term gelifluction is restricted to the slow flow of fluidized superficial deposits during the thawing of seasonally frozen ground. The flow is initiated by meltwater from thawing ice lenses. Polymict deposit: comprises gravel, sand and clay depending on upslope source and distance from source. Locally with lenses of silt, clay or peat and organic material.
Definition of Lower Boundary: none recorded or not applicable
Definition of Upper Boundary: none recorded or not applicable
Thickness: none recorded or not applicable
Geographical Limits: none recorded or not applicable
Parent Unit: Mass movement deposits (MASMD)
Previous Name(s): Head Gravel [Obsolete Name and Code: Use HEAD] (HEG)
Alternative Name(s): none recorded or not applicable
none recorded or not applicable
McMillan, A A and Powell, J H. 1999. The classification of artificial (man made) ground and natural superficial deposits. British Geological Survey Research Report, RR/99/04. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E221 E237 E021 E014 S031 E219 E225 E203 E078 E070 E077 E181 E355 E356 E142 E024 E028 E048 S024 E268 S032 S040 S034 E059 S084 S030 S064 S074 S076 S093 S093 S097 S096 E281 E246 E341 E342 E343 E217 E264 E353 E354 E314 E326 E171 E096 E214 E327