150 



So sudden is tlie change of the fauna, that even were the slight uncon- 

 formity more difficult to detect than it really is, there could be no doubt of 

 its existence. It was in vain Mr. la Touche or myself, in a baking sun, set our- 

 selves steadily to puU down and examine the shale. Pcntamerus and Atrypa 

 everywhere — but not a Caradoc fossil, such as must have mingled with them 

 had there been a true passage from one rock to the other. 



Next, I measured the thickness of the Blay Hill band up to the point 

 where the green-grey shale is mingled with purple shale, and at the utmost 

 this can only be 30 to 35 feet ; beyond which 20 to 25 feet may be reckoned for 

 l^e cIaret-<!oloured purple shale. 



Returning to the junction at the holly tree, 12 feet of alternating lime- 

 stone bands and gi-een-grey shale take us to a bed, 6 inches thick, of calcareous 

 sandstone, very micaceous, and permeated throughout with worm bvuTOws and 

 tracks on the flat lines of bedding. I do not stop to describe these here — they 

 are simple and branched — the branched ones being what are commonly and 

 falsely called Fucoids, This bed, in which are uo Pentaineri, shows the jointed 

 structure to which I beg to direct the attention of the club. It is cut up into 

 inumerable dice-like blocks, the sides of which lie respectively in the directioa 

 of the valley, i.e., 35° north of west, and the direction of the Great "Wenlock 

 Valley 30' east of north. The latter direction is not exact, but the main joints 

 are in the direction of the Onny, along which, sometimes crossing the stream, 

 sometimes keeping to the north or south of it, runs a " fault," which is not laid 

 down on the map, but probably extends qiiite into Wenlock Edge. The direc- 

 tion of these joints should be carefully noted on the map. The result would be 

 veiy obvious in a few years, for the relation of the jointed structure to the 

 faults of the district is more than probable — it is in many cases proveable. \Ve 

 must i^roceed with our section. 



Six feet of very green shale, like the Caradoc, above this band, takes us 

 to a similar band four inches thick. The green shale stUl contains Pcntamerus 

 linguifer, Strophomena applanata, with the Leptcena transvcrsalis. And now 

 comes eighteen feet more of rubbly shale, greenish and gray, and in its upper 

 part striped by numerous purple layers. It is interstratified with thinner and 

 thicker layers of calcareous sandstone, fuU of mica, and marked in some layers 

 by worm tracks : in others more calcareous, sandy, and f uU of the fry of Lep- 

 tcena, Atrypa., and Chonetcs. Twenty feet of purple shales, rich in fossils, com- 

 clude the section, for beyond this point, I think, no beds show on the water's 

 edge. Either the fault crosses here, or the soft layers, no longer protected by 

 the intervening bands of limestone, have been whoUy denuded, a clayey drift 

 filling up the low ground. 



