1866.] HAEKNESS AND NICHOLSON LAKE-COUNTRY. 481 



The upper portion of the Skiddaw slates, which is more soft and 

 shaly than the middle and lower parts of the group, has also recently 

 furnished fossils which are new to this series in the north of Eng- 

 land. The locality yielding these fossils is not in the Lake-country 

 proper, but a spot in the north-east of Westmoreland. The twenty- 

 first volume of the Quarterly Journal of the Geological Society, page 

 239, contains a section of the Lower Silurian rocks which occur im- 

 mediately west of the Pennine escarpment, showing the Skiddaw slates 

 rising from beneath the greenstones, porphyries, and ash-beds which 

 form Burney Hill. The Skiddaw slates here form an axis, the north 

 side of which is overlain by the greenstones, porphyries, and ash-beds 

 of Grumpley Hill ; and immediately north of the axis, and cutting 

 through the Skiddaw slates, is Crowdundle Beck, into which a small 

 stream flows, which exposes a fine section of their higher beds. The 

 fossils which this section affords are principally Graptolites, among 

 which is Diplograpsus teretiusculus, a form not hitherto recognized in 

 the Skiddaw slates; and from this locality there has also been obtained 

 Ajjnostus Morei, Salter. 



These additions to the fauna of the Skiddaw slates — a series of 

 deposits which was for a long time regarded as almost unfossiliferous 

 — although not large, are important, as they furnish for the first time 

 evidences of the existence of Trilobites and Brachiopoda in strata 

 which represent the Lower Llandeilo rocks in the north of England. 



The thick series of greenstones, porphyries, and ash-beds which 

 in the Lake-country succeeds the Skiddaw slates, has hitherto yielded 

 no fossils, although the slaty ash-beds have been carefully examined 

 for them. These newer rocks are the result of very different condi- 

 tions from those which gave rise to the Skiddaw slates, the latter 

 being purely sedimentary rocks,while the formerwere produced, either 

 directly (as in the case of the greenstones ^d porphyries) or indi- 

 rectly (in the state of ash-beds), by igneous causes. Notwithstanding 

 the difference in the origin of these two groups of Lower Silurian 

 rocks of the Lake-country, there does not appear to be sufficient 

 evidence to show that any unconformability exists between the Skid- 

 daw slates and the succeeding green rocks. 



The band of Lower Silurian rocks which in Cumberland and 

 Westmoreland lies immediately west of the Pennine escarpment 

 contains, among the greenstones, porphyries, and ash-beds, a highly 

 fossihferous zone, the strata forming which are dark flaggy rocks, 

 reposing on ash-beds which overlie the porphyry of Dufton Pike ; 

 and this fossiliferous zone is succeeded by porphyry*. The igneous 

 rocks of this district bear great resemblance to those of the Lake- 

 country ; but the fossiliferous zone has a more decidedly sedimentary 

 aspect than any of the ash-beds which are associated with the green- 

 stones and porphyries of the latter area. 



Notwithstanding this difference in mineral nature, there is in the 

 Lake-country a zone corresponding with the fossiliferous band of 

 North-east Westmoreland ; and it also affords fossils. 



The porphyry which, among the Lower Silurian beds on the west 

 ^ Quart. Jourii. Geol. Soc. vol. xxi. p. 242. 



