DEPOSITS IN THE BRISTOL DISTRICT. 



75 



Liassic Vein. — The working of the limestone in this quarry has ter- 

 minated on the western side against a vein from 10 to 12 feet thick, 

 which has received an infilling of yellow clay of an entirely different 

 lithological character from those last mentioned. So far as the evi- 

 dence goes, it is apparently a vein of true Lower Lias, with occa- 

 sional weathered blocks of Carboniferous Limestone. All the remains 

 found are Liassic, and consist of : — 



Teeth and scales of fishes. 



Ammonites (young). 



Univalves (several species). 



Astarte. 



Modiola. 



Lima. 



Cardium 



Gryphgea. 

 Terebratula. 



Cidaris (teeth, plates, and spines). 



Pentacrinites. 



Cristellaria. 



Webbina. 



All the phenomena I have mentioned, from the Quarry Steps to 

 the Avenue Quarry, are embraced in less than half a mile. "Without 

 including the Reptilian deposit, eleven veins are shown to be pre- 

 sent ; and but for a considerable part of the edge of the Down being 

 covered, no doubt many others would have been seen. 



The Illicttic Bone-led. — There are no workings between the 

 Avenue Quarry and the neighbourhood of the Clifton suspension- 

 bridge. The road to the latter is cut through Carboniferous Lime- 

 stone containing many veins, which are usually filled with calc-spar 

 and other mineralized matter. Looking towards the Observatory, 

 there are two veins. One, filled with limestone, has been left boldly 

 standing up by the quarrymen ; but nothing can be said of its age. 

 Close to the toll-house, however, on the Clifton side, there is a 

 deposit of considerable interest, having a face of about forty feet, in 

 which the Rhsetic bone-bed and its associated remains are present. 

 It is partly composed of irony and yellow sandy-looking marl, 

 with many free crystals of carbonate of lime, as in the Holwell 

 fossiliferous infilling ; and there are also patches of finely laminated 

 rock, similar to the Rhsetic "White Lias." Some of the associated 

 blocks of stone appear to be fossiliferous ; but as the deposit forms the 

 boundary- wall of the toll-house, they cannot well be broken down 

 for examination. The bone-bed is two inches thick, with teeth of 

 SauricWiys apiccdis, Loplxodm minimus, and many fish-scales ; and 

 the clay on either side contains fish-remains of the same age. 



In Professor Ramsay's ' Physical Geology and Geography of 

 Great Britain,' he has given a very pretty sketch of the Gorge of the 

 Avon, with the Suspension-bridge and its beautiful scenery, which, 

 through the kindness of Prof. Ramsay and of Mr. Stanford, the pub- 

 lisher, I am permitted to use (fig. 3). Curiously enough, it includes 

 the Rhsetic bone-bed, and, on the shoulder of limestone looking down 

 the river on the east, the conglomerate mentioned below. The Car- 

 boniferous Limestone dips rapidly to the south under the Bedminster 

 coal-beds, and disappears under beds of New Red Sandstone. A 

 lighter line in the sketch, between the eastern abutment of the bridge 

 and the houses on the level of the roadway, with the Observatory 

 seen beyond it in the distance, shows the exact position of the Rhsetic 

 deposit. 



