ON THE STOCKDALE SHALES. 



681 



fault, which dies out before we reach the rake, brings the Browgill 

 Beds against the Middle Skelgill Beds, and between the two faults 

 these latter occur in an overfolded synclinal, as shown in the figure. 

 The lowest beds seen belong to A?) 4, the glaber-zone, of which a 

 few inches are seen in contact with the Lower Skelgill Beds, whilst 

 two feet are visible resting against the second fault. These beds 

 are blue mudstones, of the same character as those we have had 

 frequent occasion to describe, but we have found no fossils therein 

 at this spot. Their identification is rendered certain by their 

 position, for they pass into the newer beds of the synclinal. 



It is evident that the strike-fault between the Lower and Middle 

 Skelgill Beds is more important here than at Skelgill, and the result 

 is that the zones of Encrinurus punctatus and Monograptus ar- 

 genteus are unrepresented in this section. 



Ab 5. Continuing the description of the beds in the isocline, we 

 observe the glaber-m.udstones passing up into 1 foot 6 inches of 

 black shales, in which the Graptolites are well preserved in relief. 



Succeeding these are some pale-greenish mudstones apparently 

 devoid of fossils, and above them we meet with about four feet of 

 blackish shales, with olive-brown staining along the joint-surfaces, 

 and containing Monograptus convolutus with its usual associates. 

 The list of fossils found in these shales in Browgill will be enu- 

 merated after describing the shales of this zone seen at the rake ; 

 but in the meantime we would mention that we found one specimen 

 of Petalograptus cometa a few inches below the pale-green mudstones 

 in the inverted limb of the syncline, and therefore in newer beds. 



The band of black shales between the pale-green mudstones and 

 the glaber-zone is, as at Skelgill, marked by the occurrence of 

 great quantities of Diplograptus tamariscus, Nich. 



"VVe have called particular attention to this isoclinal fold, because 

 such are most exceptional in the Stockdale Shales between Browgill 

 and Coniston Waterhead, and it is the rule along that country to 

 find members of the series faulted out, and not reduplicated. 



To return to the section at the rake : — 



A thickness of one foot four inches of the convolutus-shales is 

 seen immediately above the strike-fault, these forming the extreme 

 summit of the zone, and passing up into the mudstones of the 

 succeeding zone. These shales are quite like those of the con- 

 volutus-zone in Skelgill, viz. greyish-blue shales, with olive-brown 

 stains along the joint-surfaces. 



"We have obtained from the M.-convolutus zone of Browgill : — 



Monograptus convolutus, His. 



gregarius, Lapw. 



Nicoli, HarJcn. 



proteus, Barr. 



attenuatus, Hopk. 



Rastrites hybridiis, Lapw. 

 Retiolites perlatus, ]!^ich. 

 Diplograptus Hughesii, Nich. 



tamariscus, isich. 



Petalograptus cometa, Gein. 



Ab 5. The beds into which the shales of the preceding zone pass up 

 consist here of pale-green mudstones, having a very ferruginous, 

 calcareous, nodular band near the summit ; the whole has a thickness 



