388 Professor J. Phillips, [March 13, 



Hill, where ca narrow boss of the rocks of fusion is covered by the 

 sandstone. 



After the formation of this sandstone, the sea bed in the Mal- 

 vern district probably experienced a great depression ; for the next 

 deposit, laminated black shale (c?), some hundreds of feet tliick, 

 indicates deep sea and tranquil subsidence. In this shale, some 

 twelve years ago, I found the minute trilobitic crustaceans known 

 as Olenus humilis, O. bisulcatus and O. spinulosus. Agnostus 

 pisiformis was afterwards found by Mr. Strickland ; and I have 

 since seen a graptolithus which was discovered in them by Miss M. 

 Lowe, and a minute Discina. Thus the Olenus shale of Malvern, 

 is very analogous to the Alaunschiefer of Norway, one of the 

 oldest of the Lower Palaeozoic strata, and like that rests on 

 fucoidal sandstone. Then followed an irruption of igneous rocks 

 (e), which have burst through the syenite, the sandstone, and 

 the shale, and now fill fissures in these rocks. The shale is 

 bleached, and the sandstone is indurated, and otherwise altered by 

 the dykes. The intrusive rocks of this era are either greenstone, 

 or of a felspathic character. They are found in several small 

 mounds, above the black shales, in a little crescent on the west side 

 of the Malvern chain, and must be regarded as quite distinct in 

 geological age and mineral constitution from the ordinary and more 

 ancient plutonic rock of the hills. Such cases of greenstone dykes, 

 formed at a later period than granitic and syenitic rocks in the 

 same region, occur elsewhere ; and show that, under a given surface, 

 fused rocks of different quality have been flowing at different times 

 — the trisilicated compounds being oldest. 



Conglomerate beds, containing small fragments of syenite, 

 masses of felspar, and quartz, and sandstones of gray and purple 

 hues succeed (/), and are traced both at the north and south ends of 

 the chain, but not in the middle parts ; which perhaps might then 

 be partially above water, so as to cause local unconformity. These 

 strata, which are about 600 feet thick, are quite vertical at the 

 north end of the ridge, and but moderately inclined in the 

 southern part, where they form a bold ridge beyond the crescent of 

 the bosses of trap. The organic remains found in these strata are 

 not numerous, except towards the upper part, near the obelisk, in 

 Eastnor Park. They are on the whole more allied to Upper 

 Silurian than to Lower Silurian forms, but include besides some 

 peculiar species, as Area Eastnori, Lingula crumena, L. attenuata, 

 and several Nuculae. Trilobites are very rare in this group of 

 strata. The strata next succeeding, are usually sandstones of 

 finer grain, in thinner laminae, alternating with sandy shales, to 

 which as a really distinct member of the series, I gave the name of 

 " Upper Carodoc.^' It is now called Mayhill sandstone {g). 



In the upper part, the hard beds are occasionally subcalcareous, 

 and thus indicate the passage to the Woolhope limestone series ; in 

 the lower part, perhaps at the very boundary, is a remarkable very 



