Silurian Rocks

Lumsden Burn © BGSThe Silurian Period extended from 443 to 417 million years ago. Named after a British tribe, the Silures, who lived in southern Wales and the Welsh Borderland, where rocks of this age dominate the exposure, the Silurian is divided into four series: Llandovery, Wenlock, Ludlow and Prídolí. Only rocks from the Wenlock Series, dating from 428 to 422 million years ago, are exposed in the district. Now used internationally, the Wenlock Series was first described from the wooded scarp of Wenlock Edge in Shropshire.

Influence on the landscape

Because of their limited outcrop these rocks have little impact on the landscape. Much of the outcrop is concealed beneath thick deposits of glacial till and peat.

Influence on biodiversity

Because of their limited outcrop these rocks have little impact on the biodiversity.

Economic use

These rocks are not known to have had any economic use within the district and future commercial interest is extremely unlikely.

Conservation issues

None of the outcrops has SSSI protection. Most of the exposures within the district are not thought to be under any significant threat, other than those normally associated with the weathering of natural outcrops and stream sections.

Wider importance/significance

Although covering a relatively small surface area, the few outcrops of Silurian rocks visible within the district are the only evidence of basement rocks within this part of northern England. They therefore contribute significantly to our understanding of the geological history of the area and the geological history of Great Britain.

The sediments of the Coquet Head Inlier contain the diagnostic characteristics which are taken to indicate deposition by turbidity currents. Although few in number, the palaeocurrent (direction of ancient water flow) data are important in consideration of British Wenlock palaeogeography.

Geological SNCI

• Whitelee Bridge Road Cutting