468 George Horace Flymen — 



figure/ and differs from the somewhat more transverse form met 

 with in the " Brachiopod Beds " of the Midland area. Good 

 figures of this last variety (which might be called var. transversa) 

 are given by Davidson, based upon specimens from Park Hill.^ 

 I possess examples of the same variety from Middle Hill, near 

 Castleton (associated with Streptorhynchus senilis Phil.),^ and from 

 Narrowdale Hill, near Wetton. 



On the Occurrence of Pre-Cambrian Shale in 

 Guernsey. 



By George 'Horace Flymen, M.Sc, Ph.D., F.G.S. 



TT was noted by the Eev. C. Noury ^ in 1886 that sedimentary 

 -^ rocks were found in a small coastal area to the south of Fort 

 Pezerie, on the south-western extremity of Guernsey. Pro- 

 fessor T. G. Bonney ® observed the same area independently in 

 September, 1910, after describing it in field notes in 1888 as a close- 

 jointed and rather schistose diabase. The Eev. E. Hill ® in 1884 

 had also regarded the rock in this area as constituting a dyke-formed 

 diabase. 



Fig. 1. — Pre-Cambrian Shale, Torteval, Guernsey. 



Professor Bonney, on submitting slices of the rock to micro- 

 scopical examination, defined it as a grit. He recognized sub-angular 

 and fairly rounded quartz, felspar with (in cases) signs of plagioclase, 

 and dark brown, barely translucent, iron oxide in grains. The 

 matrix was observed to be a mozaic of quartz and reconstituted 

 felspar, with films of mica, varying in colour from green to colourless. 



Although regarded as pre-Cambrian, this patch of sedimentary 

 rock has not a close similarity to the pre-Cambrian shales of Jersey ; 

 but its occurrence in an area of intense crushing and faulting, 

 probably with accompanying metamorphism, gives reason for 

 apparent dissimilarity. It may well represent the quartzose " grey- 

 wacke " beds. Which alternate with more typical mudstones, familiar 



^ J. Phillips, Geology of Yorkshire, vol. ii, " The Mountain Limestone," 

 1836, p. xi, fig. 7. 



^ Davidson, op. cit., ii, pi. xiv, figs. 1-4. 



^ Ibid., ii, pi. xxvii, fi2. 2. 



* GMogie de Jersey, par. R. P. Ch. Noury, S.J. 1886. 



^ Quart. Journ. Geol. Soc, vol. Ixviii, 1912, p. 47. 



♦^ Quart. Journ. Geol. Soc, vol. xl, 1884, p. 417. 



