DEPOSITS IN" THE BRISTOL DISTRICT. 



73 



Fig. 2. Sketch Section of the Thecodontosaurus-6ei of Durdham 



Down. (Drawn by W. Sanders, Esq., F.R.S.) 



a. Conglomerate of New Red Sandstone. 



b. Locality of Thecodontosaurus. c. New Red Sandstone. 

 d. Carboniferous Limestone. 



section described below, which embraces a line of working from the 

 Quarry Steps to a large quarry which I call the " Avenue Quarry " 

 (from its being immediately north of the Avenue Road), a distance 

 all together of about 680 yards, I shall show the presence, as at Hol- 

 well and elsewhere, of a series of veins with infiilings derived from 

 different geological ages ; and my interpretation of the reptilian 

 deposit therefore is that it is one of such a series in Carboniferous 

 Limestone, by which, on both sides, it is surrounded. 



Durdham Down Section. — From the Quarry Steps to the end of 

 Bellevue Terrace, within which area the reptilia were found, is about 

 300 yards. Until lately these were the last houses fringing the Down 

 to the west ; and there then stood up by itself, like a wall, a large 

 vein-infilling (the limestone having been worked up to it on both 

 sides; separating the garden of the last house from an adjoining 

 quarry. Other buildings have now occupied the line of the quarry, 

 covering up four smaller veins ; but the one above referred to, from 

 14 to 16 feet in thickness, is still utilized as a boundary between the 

 gardens. It has the same general lithological character as that at 

 Quarry Steps, but has occasionally small pockets of iron-ore, and is 

 more mineralized. I purposed to examine these veins closely for 

 organisms, but have been prevented. 



Passing along the roadway from this quarry, the next vein seen 

 was one containing haematite iron-ore, at its thickest about 16 feet. 

 It had been worked up to the roadway on the edge of the Down. 

 At my last visit this also was being filled up, and a house built 

 across it. 



Alluvial Veins with Liassic and fthmtic Remains. — For about 

 200 yards from the iron-ore vein the limestone has been unworked. 

 Following the road to a spot near the ventilating-shaft of the 

 Avonmouth Railway, an archway facing the road leads into the 

 Avenue Quarry, which presents some interesting features. For 

 many years a lump of seemingly stratified yellow marl had been left 

 in the bottom of the quarry, the limestone having been worked 



