Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/833

 daloids, and breccias, with subordinate bands of trap. The lowest beds of this series are cleaved felspathic ashes, partly brecciated ; these are followed by a very beautiful amygdaloid, composed of a fine-grained green felspathic base, with large oval or rounded cavities, mostly filled with crystalline carbonate of lime, but often empty, and exhibiting a fine vitreous glaze. Above this amygdaloid come ashes and breccias again, of which the ashy bands form a very good fine- grained green slate, which is largely worked at Dale Head and in the celebrated quarries of Honister Crag. The breccias are cleaved and also form a slate, which is sometimes green, sometimes purple in colour. Of the subordinate trappean bands one of the most noticeable is a fine purple felstone, containing numerous large crystals of greenish felspar. This great slaty series extends as far as the summit of Borrowdale Hawse, and it is the unquestionable equivalent of the breccias and slates which are worked at the entrance of Borrowdale. Succeeding these in the S.E. flanks of Seatoller Fell is a massive trap, sometimes fine-grained, sometimes porphyritic, and very well exposed in the course of Horse Gill. At Seatoller itself brecciated ashy beds again succeed to this trap (fig. 1).

Fig. 1. — Section from Manesty, on the west side of Derwentwater, to Seatoller, in Borrowdale. Distance four miles.

a. Skiddaw Slates. b. Felspathic trap, forming the base of the Green-slate series. c. Great series of ashes, breccias, and amygdaloids, with some intercalated bands of trap. d. Trap.

II. Lower portion of the Green-slate Series on the east side of Borrowdale.

On the eastern side of Derwentwater the relations of the Green Slates and Porphyries in their lower portion are by no means so clear as in Borrowdale and in the Gatesgarth Valley, there being much folding and apparently several faults.

At Keswick itself the Skiddaw Slates are seen m the bed of the Greta, dipping S.S.E. at high angles (fig 2). To the south of this, in a little wooded hill called Castle Head, there is a massive greenish grey felspathic trap, containing a good deal of hornblende. Proceeding along the eastern side of Derwentwater, the next rock which is seen in situ is a massive red breccia, which occurs in Great Wood at the base of Wallow Crag. This red breccia consists of a dark red matrix, containing numerous angular fragments of felspathic ash

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