Volcanic rocks in the Lake District

in Rock

To the casual visitor, fell walker or rock climber it is this scenery associated with the Borrowdale Volcanic rocks which typifies the hotels in the lake district . Starting from the southwest fringe where volcanic rocks encircle Black Coombe , the outcrop extends as a broad strip in a northeasterly direction to include most of the fells, high plateaux and high mountain peaks of the central Lake District. In the Coniston Fells many of the mountain tops are above 2,500 ft and include Coniston Old Man, Dow Crag , Swirl Howe  and the broad saddleback ridge of Wetherlam.

Here the varied assemblage of volcanic beds is responsible for a landscape of contrasts. The undissected plateau tops such as that of Brim Fell leading up to Coniston Old Man tends to be gently rounded with a few bare rock outcrops projecting through a superficial cover of broken rock fragments which the short tufty grasses have only partially colonized. The Old Man itself represents a rocky tor dominating the end of the ridge.
From its top the view eastwards lies across Coniston Water to the beveled plateau surface of the Furness Fells, composed of Silurian flags, shale's and grits. To the west and within a stone's throw, across the deeply set darkened hollow which encloses Goat's Water, lie the great rock buttresses of Dow Crag.

Although slightly lower than the Coniston Old Man, the sheer face of the crag rising out of its own screes is one of the finest in the whole Lake District. The rock wall is broken in places by great gullies or rakes which have been etched out along narrow zones of shattered rock. The volcanic rocks, with their regular joint planes, are particularly prone to shattering in this way, and where weathering and stream erosion have exploited the weakness the massive rock is broken up into great slices. The main gash on Dow Crag is only a few feet wide, but looking down from the top it forms an almost vertical 'chimney' descending to the dark placid surface of Goat's Water.

Some of these gashes are formed where dykes of intruded rock weather more easily than the surrounding volcanic beds. The wide cleft of Mickledore which separates the twin peaks Scafell and Scafell Pike is associated with a dyke of less resistant rock passing through it. On Dow Crag the effect of the development of clefts has been to give it the appearance of a number of tarlike rock masses rising abruptly out of the general level surface of the narrow ridge crest. Around lie a mass of broken angular boulders reminiscent of the clitter* slopes which encompass the Dartmoor granite tors.

Impressive though the precipice of Dow Crag is, it is in the Scafell area that the Borrowdale Volcanic Series gives rise to the most rugged and wildest scenery . Had the eighteenth century etchers been able to penetrate this innermost recess they surely would have chosen the sheer rock buttress of Great End  or Lord's Rake rather than the Jaws of Borrow¬dale or the Bowder Stone , their more usual subjects. Not only is this the highest part of the Lake District but it is also the great knot at the center of a series of radiating valleys. Seen from many of the surrounding low peaks both Scafell and Scafell Pikes stand out unmistakably.

This is country far away from the roads where the fell walker can thread his way through the upper valley sections, up the rock strewn slopes to his goal of the twin summits separated by the col of Mickledore. The volcanic rocks of the Scafell region form part of a great syncline or downwarp in the strata. In character they consist of a variable suite, ranging from the coarsest brecciate of broken rock fragments down to the finest volcanic dust. Many of the rock types present are flinty in character and these resist erosion.

This is particularly true of the thick ash bands which have been altered and hardened by heat. Some of the ash bands have escaped this alteration and it is in these beds that the workable slates are found. In the past they have been extensively quarried in a broad band which runs from Walna Scar , through the slope below Coniston Old Man  past Tilberthwaite, and the Elterwater area , and then across to the valleys of south¬east Lake District like Kentmere and Long Sleddale. Only a few of these areas still produce workable slates at the present time.

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Adrian vultur writes for hotels in the lake district

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Volcanic rocks in the Lake District

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This article was published on 2011/01/01