THE SHAP GRANITE AND ASSOCIATED KOCKS. 209 



upper, but is by no means pure. At its base is a breccia, which 

 is somewhat variable, consisting of a calcareous ashy matrix with 

 rounded and angular fragments of rhyolite. The upper part of 

 this breccia consists of a limestone with a few more or less 

 rounded rhyolite fragments, whilst the base is to a large extent 

 composed of rhyolitic detritus with comparatively little calcareous 

 matter. This breccia is seen occupying precisely the same position 

 at Yarlside Crag, again at a point -J mile W.S.W. of Wasdale 

 Head Farm, immediately west of the farm itself, and in Blea 

 Beck, at the Spa Well in the grounds of Shap Wells Hotel. Below 

 this is a thin ash band, and then a thick rhyolite, nodular at the 

 summit and fissile below. This is well known, being inserted on 

 the Survey Map from Wasdale Head Farm to Stile End, on the 

 west side of Long Sleddale, a total distance of over five miles, and 

 it is the rock which is figured in Mr. Teall's " British Petrography," 

 plate xxxviii., the specimen figured having been obtained from a 

 point half a mile W. of Stockdale. 



The Lower Limestone (Stile End Limestone) is less calcareous 

 and more ashy than the upper one, and the calcareous matter is 

 often collected into nodules. 



The Khyolitic Group below the Coniston Limestone, and forming 

 here the summit of the Borrowdale series, consists of a succession 

 of fine green rhyolitic ashes and breccias of no great coarseness, 

 the latter containing rhyolitic fragments *. It will be eventually 

 seen that farther to the west this group also contains rhyolite flows, 

 and beds of a gritty character, which are not found in the present 

 section, but fortunately their nature is readily recognizable even 

 within the zone of alteration. 



Lastly, below Grey Crag we meet with a group of vesicular 

 andesites, interstratified with darker ashes, and with some breccias, 

 the latter containing rhyolitic fragments, as is usually the case 

 throughout the whole Borrowdale series whatsoever may be the 

 nature of the associated lavas. These andesites have evidently 

 undergone " weathering " at an early period, as their vesicles are 

 now filled with calcite, chlorite, or both, and when the rocks have 

 been subjected to cleavage, the vesicles have been flattened along 

 the cleavage-planes. 



In order to show the fairly constant character of the rocks above 

 described, it will be convenient to give details of two other sections, 

 one near the granite, and the other somewhat more remote, though 

 still within the zone of alteration. 



The section (fig. 2, p. 271) is taken obliquely across the strike of 

 the beds (which has here curved round somewhat in a manner to be 

 described in the sequel), being drawn from Demings Moss, about 

 ^ mile S. of the granite margin, to Wasdale Pike. The Coniston 

 Grits are seen at Demings Moss, and the Upper Coldwell Beds 

 extend from here to the summit of Backhouse Hill, in a somewhat 



* In figs. 1-3, amongst the volcanic rocks, the wrinkled lines indicate 

 rhyolite flows, the oval markings andesite flows, whilst rhyolitic and andesitic 

 ashes are indicated by fine dots, and breccias bj' triangles. 



