The BGS Lexicon of Named Rock Units — Result Details

Marchfield Moraine Member

Computer Code: MMO Preferred Map Code: notEntered
Status Code: Full
Age range: Devensian Stage (QD) — Devensian Stage (QD)
Lithological Description: Interstratified sequence dominated by Sand and Gravel. Subsidiary lithologies: Reddish brown glacial Diamicton(till), Silt and Clay. Lithologically very heterogeneous. Gravel and diamicton dominate at the type section; fine-to medium-grained sand and silt dominate in many surface exposures. These show extensive small-scale normal faulting and some low-angle glacitectonic thrusting.
Definition of Lower Boundary: Not exposed, but probably a gradational contact on till of the Gretna Till Formation.
Definition of Upper Boundary: Normally the ground surface; locally overlain by Holocene peat in hollows in the moraine surface.
Thickness: At least 12m thick at type section; at least 7.4 to 11.3m proved in adjacent boreholes.
Geographical Limits: Extends from Cargenbridge [NX 955 745], northnortheastwards to the vicinity of "The Grove" [NX 986 796] Dumfries, Dumfriesshire.
Parent Unit: Kerr Moraine Formation (KEMO)
Previous Name(s): none recorded or not applicable
Alternative Name(s): none recorded or not applicable
Stratotypes:
Reference Section  Exposed section on new housing estate (Record CA 1325). Exposed face up to 2m high in highly sheared and fractured sequence of grey lithic sand, and laminated red-brown and pale brown silt and clay (glaciolacustrine sediments incorporated in a push moraine ridge). 
Partial Type Section  Dumfries By-Pass site investigation BGS Reg No. SE 13972, borehole BR31A. Whole of borehole log beneath topsoil to total depth of 12m. Shows interbedded sequence of reddish brown silty gravel (sandy diamicton), dark brown sand and gravel, firm pinkish brown "gravelly clay" (clayey diamicton), clayey silt and cobble gravel. Drilling difficulties (chiselling) identified in log suggest the sporadic presence of large boulders. 
Reference(s):
British Geological Survey. 2005. Solway West. Scotland Special sheet. Superficial Deposits and Simplified Bedrock. 1: 50 000 Geology Series. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S010 S009