Devon County Geological Site

Site reference no. SY09SE1 Name: Beggars Roost Quarry

District: East Devon Parish: Rockbeare

National grid ref: 062942 OS sheets: 1:50k 192 1:25k 1315 1:10k SY69SE GS 1:50k GridRef x y Lat Long SY062941 306200 94100 50.738909 -3.3306646

Locality description (address): Rockbeare Hill, entrance 100m west of the cross-roads on the B3180.

Nature of site: Quarry (D) medium, has been used as a silt settling pond.

Geological / geomorphological features: Triassic, Otter Sandstone overlying Budleigh Salterton Pebble Beds. The Budleigh Salterton Pebble Beds are exposed for up to 5m above the sloping surface of the silt infill. Pebbles and cobbles of typical quartzite are associated with quartz, tourmalinite, quartz porphyry and occasional greenish dolerite/gabbro pebbles A feature here is the occurrence of arkosic sandstone pebbles of varying coarseness. On the west face flatter pebbles show marked imbrication indicating current flow from the south. The top of the Pebble Beds on the east face is marked by a layer of ventifacts, with polished and pitted and occasionally faceted upper surfaces and with etched lower surfaces. Faceted pebbles show no preferred orientation. The Otter Sandstone is exposed for 8m in the upper parts of the face. They are very weakly cemented fine to coarse sand with a general bedding picked out by colour variations in orange yellow and buff. They also contain lenses and beds of pebbles and gravel. In detail the sandstones are trough cross- bedded. And contain intraclasts of red mudstone. Minor faults occur on the north and east faces.

Reasons for registration as a Regionally Important Geological / Geomorphological Site: The quarry provides a first class exposure of the junction between the Budleigh Salterton Pebble Beds and the Otter Sandstone with the characteristic ventifact horizon at the top of the pebble beds indicating a considerable period of exposure as a land surface. The quarry also shows excellent examples of the sedimentary features of the Pebble Beds and Otter Sandstone indicating their mode and direction of deposition. The basic igneous and arkose pebbles are uncommon. Minor faults are also present.

Site sensitivity: Further infilling would ultimately result in loss of significant geological features.

Safety: The faces are subject to falls of pebbles and sand, particularly during wet and frosty weather. The infill of the pit becomes very soft and clayey in the north eastern part of the pit and access to the faces is along a narrow tallus slope below the face. In wet weather access could be difficult, with some risk of becoming trapped in mud.

Interest groups: Schools. Years 5-11: Years 12-16: Years 17-18. University. Undergraduate - Research Professional geologists - Amateur geologists - General public.

Access and Parking: Locked, gated entrance to quarry access ramp, passable on foot. Parking for groups of vehicles at National Trust car park 200m to north. On the B3180. Footpath through National Trust land to quarry entrance on Rockbeare Hill. Parking for single vehicles on Rockbeare Hill.

Date of assessment (V = visited) : V 8th May 1996 R T Taylor

Site owner : Camas Aggregates, Rockbeare Hill Quarry, Rockbeare, Exeter. EX5 2HB. Tel. 01404 - 821400

Other comments: Edwards (1990) recorded a 9m section of Pebble Beds when the pit was already being filled.

References: EDWARDS, R.A. and SMITH, S.A., 1989. Budleigh Salterton Pebble Beds and Otter Sandstone Boundary in East Devon. British Geological Survey Technical Report. WA/89/97. British Geological Survey, Exeter. EDWARDS, R.A., 1990. Geology of the West Hill District (Sheet SY09SE). British Geological Survey Technical Report. WA/90/1. British Geological Survey, Exeter. SMITH, S.A. AND EDWARDS, R. A., 1991. Regional Sedimentological variations in Lower Triassic fluvial conglomerates (Budleigh Salterton Pebble Beds), south west England: some implications for palaeogeography and basin evolution. Geological Journal, Vol. 26, pp. 68-83.