THE CAMBRIAN SYSTEM -'. 



and of greenish flaggy micaceous sandstone which have been called 

 the Hollybush sandstone. In these beds Dr. T. T. Groom hat 

 recognised the following descending succession : 18 



2. Hollybush Sandstone, consisting of: 



b. Massive glauconitic sandstones, from 550 to 700 feet 

 thick, with several species of Hyolithet (including H. 

 fistula}, Kutorgina cingulata var Phillipri, etc. 

 a. Shaly sandstone, with calcareous bands and seams of 

 quartzite, not less than 220 feet, with Knt. Phillipii, 

 Obolella sp. t Linnarssonia sagittalis, Hyolithes tp. 

 1. Hollybush Quartzite. Quartzites and conglomerates of un- 

 known thickness, with Kutorgina, Obolella, and Hyolithct. 



The conglomerates in the quartzite contain pebbles of meta- 

 morphic quartzite, rhyolite, andesite, and red granophyre, and the 

 mass was supposed to rest unconformably on the pre-Cainbrian 

 rocks. It is probable that such was their relation, but Professor 

 Groom believes the present junction planes to be faults, and thinks 

 that the quartzite may have been several hundred feet thick, though 

 only 50 or 60 feet of it can now be seen. 



In Shropshire the Wrekin ridge, as well as the Uriconian rocks 

 of the Caradoc and Cardington Hills, are flanked on their eastern 

 sides by a series of Cambrian rocks, the lowest being a hard 

 quartzite like that of Malvern (see map, Fig. 21, here reproduced 

 by permission of Professor C. Lapworth) ; but its base is aeeii 

 to rest directly and unconformably on the Archuean rocks, and it 

 contains pebbles of rhyolite, tuff, etc., derived from them. 



This quartzite is about 300 feet thick, and is succeeded by a 

 series of sandstones, limestones, grits, and shales which are gener- 

 ally known as the Comley sandstone, though they include repre- 

 sentatives of two faunal divisions. This series is supposed to be 

 about 500 feet thick. Its true age was first recognised by Dr. 

 C. Callaway in 1877, and the Olenellus fauna was first discovered 

 in it by Professor C. Lapworth in 1888. Still later exploration 

 by Mr. G. S. Cobbold has resulted in the discovery of more fowl* 

 and has shown that the succession of fossiliforous beds at Cornier 

 is as follows : 14 



Paradoxides 

 Beds 



Olenellus 

 Beds 



Flaggy shales and grits. 



Coarse calcareous grit with fragments of sandstone and 

 l limestone derived from beds below. 

 'Black limestone witli jihosphatic nodules (1 foot). 

 Grey limestones with black phosphatic nodules (4 fet). 

 Purplish-red sandy limestone with Olfntll. 

 .Greenish felspathic sandstones. 



