Jumb Quarry

Also within

Cumbria County LAKE DISTRICT National Park

Condition (Natural England)

Habitats

Fast flowing river and stream

Geology & landscape

Mining / Industrial: Quarry

Landscape processes: Volcanic / Igneous

Description

Description Jumb Quarry is situated adjacent to the eastern banks of the River Kent just below Kentmere Reservoir about four kilometres north of Kentmere village and 9 kilometres north of Staveley. This quarry provides important exposures of volcanic rocks of the Borrowdale Group demonstrating structural features of special geological interest. Especially significant are the 'bird's eye' tuffs, containing accretionary lapilli fragments of lava erupted from a volcanic centre and probably falling into standing bodies of water. The lapilli are thought to have been originally spherical but are now distorted into ellipsoidal shapes as a result of intense compressive stress imposed during the Caledonian mountain building episode orogeny. The degree of flattening of the lapilli gives a very useful indication of the extent and nature of the distortion suffered by the rocks during the orogeny. Other notable features of the tuffs are the powerfully developed cleavage closely spaced parallel fractures and well defined orientation of the elongate lapilli, forming a prominent linear structure. The intense cleavage developed here is recognised in a belt of rocks running from Kentmere to Wrengill and has been interpreted as resulting from contact strain where tuff beds occur between massive lava flows. This site is of particular importance for the excellent exposures of lapillar tuffs in the Borrowdale Group which have attracted detailed research into the amount and nature of strain imposed during the Caledonian Orogeny.

Plant communities