The BGS Lexicon of Named Rock Units — Result Details

Fownhope Formation

Computer Code: FOW Preferred Map Code: FOW
Status Code: Pending Upgrade
Age range: Rhuddanian Age (SR) — Aeronian Age (SA)
Lithological Description: Interbedded red-brown siltstones and sandstones.
Definition of Lower Boundary: At unconformity at top of the Ordovician Tremadoc, pale grey siltstones and claystones where they are overlain by red beds of the Fownhope Formation. At 3628 feet depth in the Fownhope Borehole.
Definition of Upper Boundary: At colour change from red-beds to green-grey siltstones and sandstones of the Huntley Hill Formation. At 2326 feet depth in the Fownhope Borehole, and prominent seismic marker.
Thickness: 1302 feet drilled in Fownhope Borehole; about 370m corrected for dip.
Geographical Limits: Proved only in Fownhope Borehole; seismic evidence indicates its presence at depth to the west.
Parent Unit: May Hill Sandstone Group (MHS)
Previous Name(s): Rhuddanian-Aeronian Stages (-259)
Alternative Name(s): Cowleigh Park Formation
Stratotypes:
Reference Section  Fownhope No. 1 Borehole, Butler et al. 1997. 
Reference(s):
Barclay, W J, Ambrose K, Chadwick, R A and Pharaoh, T C. 1997. Geology of the country around Worcester. Memoir of the British Geological Survey, Sheet 199 (England and Wales). 
Butler, A J, Woodcock, N H and Stewart, D M. 1997. The Woolhope and Usk Basins; Silurian rift basins revealed by subsurface mapping of the Southern Welsh Borderland. Journal of the Geological Society of London, Vol. 154, 209 - 223. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
none recorded or not applicable