New Fossili/erous Horizon in the Lahe-didrict. 341 



•called Borrowdale rocks, while it is flanked on tlie north, and north- 

 east by a narrow strip of volcanic rocks which runs from Eycott 

 Hill near Troutbeck Station, through the range of the Caldbeck Fells, 

 to Binsey Crag and Torpenhow Common. The upward sequence of 

 the volcanic rocks of the Caldbeck Fells is concealed from view by 

 the overlapping Carboniferous Limestone. On the other hand, the 

 relations which these rocks bear to the Skiddaw Slates to the south 

 •of them have not hitherto been precisely ascertained, partly from an 

 insufficiency of sections, and partly owing to the intercalation 

 between the two series at the eastern end of the I'ange of the great 

 intrusive igneous masses of Carrock Pike and Great Lingy. 



The strata to which we wish to direct attention here are situated 

 immediately to the north of the intrusive masses just spoken of, and 

 are, therefore, of special interest as lying between the Skiddaw 

 Slates on the one hand and the volcanic rocks of the Caldbeck Fells 

 on the other hand ; though it cannot be said that their stratigraphical 

 relations with eitlier of these are absolutely clear. They occupy the 

 summit of the valley between High Pike and Carrock Pike, and are 

 fully exposed in the course of Drygill Beck, the head tributary of 

 Carrock Beck. We shall, therefore, speak of them as the " Drygill 

 Shales." The following is the section seen in Drygill in descending 

 the stream. The ridge from which Drj^gill Beck flows north-east- 

 wards is probably composed of intrusive igneous rocks, but the 

 summit of the ridge is covered with peat, and no rock is seen in 

 ■place. The first rocks seen in the highest part of Drygill are pale 

 drab-coloured shales, which dip at tolerably high angles to the S.S.W. 

 and strike W.S.W. and E.N.E. No fossils were detected in these 

 beds ; but a more prolonged search would probably bring organic 

 remains to light. These are succeeded below by blue-grey shales, 

 weathering white, and similarly coloured mudstones, with iron- 

 stained joints, containing ill-preserved Brachiopods and other fossils. 

 These beds are best seen in Drygill itself, but are also exhibited in. 

 the western fork of the stream. 



The beds just spoken of abut against a mass of intrusive igneous 

 rock, which occupies both sides of the stream for some little distance 

 below the point where the eastern and western forks unite. This 

 rock decomposes by exposure to the weather to a soft brownish- 

 green ashy-looking rock, but it seems really to be very similar to the 

 intrusive mass which occurs in Brandy Gill, and which Ward has 

 spoken of as a " diorite." Vei-y probably the mass in Drygill is only 

 an ofi'shoot from this. 



Below the preceding, the stream cuts through a series of dark 

 blue-grey or nearly black mudstones, crowded with fossils, which 

 are fairly preserved, though slightly distorted by cleavage. The 

 general strike of the beds here varies from S.W. to W.S.W., the dip 

 still being southerly ; and the whole series is much broken and inter- 

 sected by mineral veins. These beds rest upon a seines, of no great 

 thickness, of remarkable contemporaneous volcanic rocks in the 

 form of breccias with associated bands of quartz-felsite, which are 

 Mnlike the ordinary lavas and ashes of the Lake-district in their 



