Bothel Craggs Quarry

Also within

Cumbria County

Condition (Natural England)

Geology & landscape

Geological Feature: Fissure · Mining / Industrial: Quarry · Geological Period: Carboniferous · Rock Type: Andesite

Landscape processes: Volcanic / Igneous

Description

Area, 0.2 hectares 0.5 ac Description The site lies two kilometres south of the village of Bothel, some 9 kilometres north east of Cockermouth, and comprises a small disused quarry with exposures immediately to the south. The Cockermouth Lavas, of Dinantian age, record a volcanic episode linked with the initiation of the southern margin of the Northumberland Trough during early Carboniferous times. The volcanism was preferentially located along the hinge zone between areas of subsidence, to the north and uplift, to the south. The absence of pyroclastic rocks suggests that extrusion was relatively quiet, probably along a series of fissure vents. The suite is geochemically distinguished by the presence of lavas of intermediate composition and the Northumberland Basin is, in this sense, transitional between the Scottish Midland Valley where such compositions are relatively common and Derbyshire, where they are unknown. A tholeiitic andesite lava is well exposed in the quarry at Bothel Craggs. The presence of such intermediate lavas in the Cockermouth suite points to the establishment of magma chambers, at a high crustal level, in which fractionation of the parental basaltic magma took place. For this reason the site is important in understanding the origin and evolution of the Cockermouth rocks.