Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/839

 of a mile ; and if we take 30° as the average angle of dip, this would give a thickness of probably about 2000 feet, making some deduction for possible flexures. Throughout this thickness, however, there is no well-marked band of slate, and in fact nothing of a slaty nature, with the exception of the small ashy beds above alluded to. The absence, therefore, of any horizon equivalent to the great slate- band of Borrowdale is worthy of notice ; and the same obtains further to the N.W. in the Caldbeck Fells, of which, indeed, Eycott Hill is only a continuation.

VII. Lower portion of the Green-slate Series between Ulleswater and Haweswater.

The general direction of Ulleswater is N.E. and S.W., pretty nearly corresponding with the strike of the Silurian rocks of the district ; and the lower reach, at any rate, is placed in a depression which coincides with a line either of folding or of faulting. This is shown by the occurrence of a small area of Skiddaw Slates immediately to to the south-east of Pooley, the occurrence of these strata here being most probably due to an E.N.E. and W.S.W. fault, but being possibly caused by an anticlinal fold. These, in turn, are followed to the south-east by the lower members of the Green-slate series.

In ascending Aik-beck (or Eggbeck), a small stream which flows into Ulleswater from the south, close to Pooley, the first rocks exposed in situ are the upper shaly beds of the Skiddaw Slates, somewhat contorted, but having a general dip to the S.S.E. at high angles (fig. 4), The Skiddaw Slates are succeeded by bedded felspathic ashes, not more than a few feet in thickness, which graduate upwards into a felspathic trap. This trap, when unweathered, consists of a light greenish-grey felspathic matrix, containing minute specks of hornblende and scattered crystals of felspar. When weathered it is of a brownish-green colour with orange spots. Beds of ashes, with a band of grey felspathic trap, succeed, and then a series of coarse felspathic ashes, dipping S.S.E. at 40°. These ashes, with some intercalated trappean bands, continue up the stream for a considerable distance, when they are overlain by a thick mass of felspathic trap of a greenish-grey colour. This is, in turn, surmounted by an ashy conglomerate, composed of a dark-green matrix with numerous yellow spots, enclosing many small pebbles, apparently composed of trap. This conglomeratic ash passes into beds of coarse ash, which continue up the stream as far as any rocks are exposed.

Beyond the summit of the watershed there are few rock-exposures ; but Arthur's Pike, an eminence about half a mile to the south-west, is found to consist of a cleaved felspathic breccia, of a green colour, very similar in every respect to the Borrowdale Slates.

Whitestone Moor, to the south of this, exhibits no rock in situ ; but in the upper part of Heltondale Beck are seen felspathic ashes and traps, apparently dipping northwards, and very similar to the beds which occupy the higher part of Aik Beck. It would appear, therefore, that there is a synclinal axis crossing Whitestone Moor in an E.N.E. and W.S.W. direction.