Backside Beck and Spen Gill

Also within

Cumbria County YORKSHIRE DALES National Park

Condition (Natural England)

Geology & landscape

Geological Period: Ordovician, Silurian

Description

Area, 3.4 hectares 8.6 ac Description Beckside Beck and Spen Gill lie six kilometres north east of Sedbergh. The site stretches some two kilometres along the Backside Beck and includes the small tributary of Spen Gill at its headwaters. On both streams historic sections of the fossiliferous Ordovician and Silurian succession have been exposed. This section in Backside Beck has been used as a comparative section within the Ashgill since the time of Marr, who regarded the section as the type locality of the Ashgill in the Cautley area. A continuous section through the Ashgill from the Pusgillian to the Hirnantian is present, but zones 2 and 3 of the Cautleyan are faulted out. This is one of the important sections upon which the trilobite zonal scheme for the Ashgill was founded and the type locality of a number of trilobites. Spen Gill on the other hand provides a section from the Ashgill Shales late Ordovician to the Lower Coniston Grits, of Ludlow age. Llandovery Series strata include the Skelgill and Browgill Beds, the latter including the 'Red Beds'. Over one hundred and thirty species of graptolites have been recorded from this marine sequence. The locality with its important faunas provides one of the best sections through the Llandovery rocks of the Howgill Fells.