| Computer Code: |
THSA |
Preferred Map Code: |
ThS |
| Status Code: |
Full |
| Age range: |
Permian Period (P)
— Permian Period (P) |
| Lithological Description: |
Predominantly reddish brown fine- to very fine-grained sandstone, with local thin beds and partings of reddish brown clay. Lenticular breccia bed south of Raddon (c.SS 915 016); possibly other thin breccias present. Basaltic lavas at various levels. May correlate with Knowle Sandstone. |
| Definition of Lower Boundary: |
Rests on Cadbury Breccia, apparently fairly sharply, possibly unconformably; exact nature of contact uncertain. |
| Definition of Upper Boundary: |
Overlain, apparently fairly sharply and unconformably west of Thorverton by Crediton Breccia, and by Yellowford Formation elsewhere. |
| Thickness: |
To 120m |
| Geographical Limits: |
Main outcrop between West Raddon (SS 895 014), Thorverton, and Silverton. Fault-bounded outcrop around the Killerton area between Heazille (SS 947 005) in the west and Budlake (SS 985 001) in the east. |
| Parent Unit: |
Exeter Group (EXE)
|
| Previous Name(s): |
Lower Sandstone [Obsolete Name and Code: Use DAS, THSA]
(-1475)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Roadside exposures about 300m west of Chapel Farm, Raddon. Sandstone...1.7m, breccia channeled into sandstone...1.5m (Edwards, 1987). |
| Type Area |
Village of Thorverton, Devon. No suitable type section owing to poor exposure. |
| Reference(s): |
| Edwards, R A, 1984. Geological Notes and Local Details for 1:10,000 Sheets. Parts of Sheets SS80SE and SS90SW (Thorverton, Devon). British Geological Survey, Exeter. |
| Ussher, W A E. 1899. Exeter 1:63360 Geological Map. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
