Little Mell Fell Quarry
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Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| NY429239 | — | Favourable | 0.11 | 2024-04-04 |
Geology & landscape
Geological Feature: Fissure, Rock Outcrop · Mining / Industrial: Quarry · Geological Period: Carboniferous · Rock Type: Basalt
Landscape processes: Volcanic / Igneous
Description
Description Little Mell Fell is situated four kilometres west of Pooley Bridge, Ullswater, on the eastern slopes of Little Mell Fell. The site consists of a small disused quarry approximately 50 metres in length. These man made exposures of basalt are of considerable importance for geological research into a major volcanic episode occurring in the Dinantian period, 300 million years ago and also to compare with similar age rocks elsewhere. The geological interest of the site, in technical terms, may be defined as follows, 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 Basis is, in this sense, transitional between the Scottish Midland Valley where such compositions are relatively common and Derbyshire, where they are unknown. The quarry at Little Mell Fell is significant for two reasons. Firstly, the Cockermouth lavas have been subjected to pervasive alteration which has often resulted in the replacement of the original igneous mineralogy. The olivine basalt dyke at Little Mell Fell, however, is notably fresh. Secondly, the occurrence lies some thirty two kilometres to the south east of the main outcrop of Cockermouth lavas and is thus exceptional in the inference that Dinantian magmatism also occurred within the Lake District Block, well away from the block/basin hinge zone.