GF.OLOOY OP T[I15 AVON BASIN. 



of the Lower Limostono Shales, tlie Bryozoa Tied. Tt m.-irks 

 a definito horizon in this series, and in the Avon section will 

 be found in the cutting below Cook's Folly, about 120 feet 

 above that quartzose conglomerate of the Old Red Sandstone 

 •which Mr. Stoddart takes as 33 feet below the base of the 

 Lower Limestone Shales. It is, therefore, about 90 feet 

 from the base of the Shales. It is a coarse reddish Lime- 

 stone, in which arc cmbeddod cnofmoris numbers of frn-g- 

 ments of Poljzoa, Encrinital fragments, and other organic 

 remains, composed of deep rod oxide of iron. On treating 

 the rock with dilute hydrochloric acid, tlie calcareous matter 

 dissolves, and these polyzoan and other fragments remain 

 behind as an insoluble residue. I have been able to detect 

 this bod at two places in the area under consideration — at 

 the point marked c in the road opposite Racecourse Farm, 

 and at the point marked d in a quarry to the E. of Charlton 

 House. 



North of the line of depression caused by the Tjowor Ijinie- 

 stoue Shales is the Clifton-Clcvedon ridge of solid Mountain 

 Jjimestone. Tlie average dip of the beds is here about 25° 

 S.S.B. But near the Upper C!harlton Fa,rm the beds are 

 nearly vertical, with an Vu find W. strike. 'iMie rock ha.s 

 lieen quarried here for lime, and the beds exposed (at, c on 

 the map) very closely resemble those at the foot of the 

 gully near the Soa-wa,Il ; so thai, the line of depression here 

 may bo duo to the incoming of the beds that in my previous 

 paper {Awn Qorgc, p. 190) I called the Middle Limestone 

 iSliaies. The high dip must be duo to a, lo<;al roll or disloca- 

 tion of the sti'atii. 



Setting aside such loca-l disturba,nces, tlu! general direction 

 and angle of dip of the Palasozoic beds. Old Red Sandstone, 

 Ijower Limestone Shales, and Mountain Lluicsloni', Is fi-om 

 15" to 30° S.S.iO., the Dolomitic Congloiuei-alo a-nd 'I'l'iassic 



