160 



PROF. T. T. GROOM ON THE GEOLOGICAL [May 1 899, 



The Coal Hill igneous band forms a sharp ridge extending right 

 across Pendock's Grove, a second shorter ridge known as Coal Hill, 

 and an ill-marked tract of hummocky ground, constituting part of 

 the north-western slope of Chase End Hill. 



At Coal Hill Cottage, as already stated, the dip is 35° to the 

 south-west. At the south-eastern end of Coal Hill the beds are 

 vertical, and at the foot of Chase End Hill the uppermost beds of 

 the series are inverted, so as to dip east-north-eastward at 45°. In 

 the south-western part of the band, accordingly, the inversion of 

 the beds may be traced as they aj^proach the schists of Chase End 

 Hill. 



The Upper Grey Shales form a broad band of greater length than 

 the three last-mentioned zones. This extends from the north-western 

 margin of Pendock's Grove to Hayes Copse on the south, a distance 

 of about I mile. The surface of the median portion of the band is 

 depressed, and the ground rises on the one hand towards the Coal Hill 

 band, and on the other towards the May Hill Sandstone escarpment 

 (fig. 13, p. 149). The only actual exposure of the shales is seen 

 in the southern part of the district, near Hayes Copse, where the 

 inverted beds dip east-north-eastward at 27° : no igneous rocks 

 occur here. A solitary semicircular boss of basalt constitutes the 

 only prominent igneous mass seen in the Upper Grey Shales of 

 this sub- district. 



The northern corner of Pendock's Grove is occupied by a 

 quadrangular block of May Hill Sandstone (M 355) and Grit 

 (coarse sandstone), bounded on all sides by faults, which are more 

 or less clearly defined by depressions of the surface. On its eastern 

 side the sandstone is faulted against both Black and Grey Shales, 

 several of the zones of which strike up against it (see fig. 21 ). The 



Fig. 21. — Section of Camhrian and Silurian rocks, between White- 

 leaved Oak and Fowlet Farm. 



N.w^. 



[Scale : 6 inches: 



Fi^=: Faults. 



6= May Hill Sandstone, 



1 mile.] 



a = Black Shales and basalts 

 (Cambrian). 



rocks are exposed only at the extreme north-western corner of the 

 patch. The fossils found among the debris include Lindsiroemia 

 subduplicata , Tcntaculites, OrtJiis, and crinoids. A small patch of 

 Black Shales, with associated igneous rocks (M 223), occurs on the 

 southern boundary of the block. 



