90 Dr. Wright on tlic Geology of the 



The transition from tlie lower freshwater to the upper marine 

 is made by a series of beds containing estuary species, and the 

 passage from the marine to the upper freshwater is in like man- 

 ner made by several zones of estuary shells. The association of 

 the genera in the manner described is very decided. I feel satis- 

 tied that the contrary opinion has arisen from observers having 

 collected specimens from the foundered beds on the shore instead 

 of from the strata in situ. 



The beds rise very uniformly at angles varying from 1° to 5° 

 to the horizon, and incline to the east. Their continuity is inter- 

 rupted by four chines and one ravine : commencing from the 

 north and proceeding southwards are the following chines, Lyn - 

 chen, Bramble, Col well, and Weston. The ravine separates the 

 Barton series at Alum Bay from the lower freshwater beds ; down 

 this gorge a pathway leads from the rabbit warren to the shore. 

 The chines are formed by streamlets whose waters in their 

 course to the sea have cut down the clays and marls to the beach. 



The observer is supposed to walk from Sconce to Colwell and 

 Tollands Bays along the shore, thence round Headon Hill to 

 Alum Bay, and to study the beds as they rise from the shore and 

 ascend into the cliff. 



The strata appertaining to the upper freshwater formation 

 around Sconce Point have experienced much disturbance and are 

 in a state of ruin. The hill forms an uneven slope, and is much 

 rent by the breaking up of the clays and marls of which it is 

 composed ; it is covered with grass and foliage almost to the 

 water's edge. 



From some blocks of limestone near the shore I obtained Bu- 

 limus ellipticus, Paludina angulosa } and Planorbis. 



These fossils are denuded of their shell. The clays and marls 

 that form the upper part of the hill above the Coast-guard sta- 

 tion at Sconce Point contain freshwater shells in a fragmentary 

 state. 



No. 1. The first bed in situ is a band of blue clay which rises 

 on the shore at a point nearly opposite to Hurst Castle, and 

 where Worsley's Tower formerly stood. It exhibits many shelly 

 laminae. Potamomya plana is in great profusion in this bed. 

 It rests upon slate-brown, rusty, and variously coloured clays, 

 in which Paludina, Cyclas, Potamomya lie in zones. Tt is inclined 

 at an angle of about 2°, and measures about 15 feet. The line 

 of elevation has been much disturbed, and the angles which the 

 bed makes are various at different points; it disappears south of 

 Cliff End. 



No. 2. I regard as a brackish water series. It consists of 

 bands of bluish or slate-coloured clays with zones of Cyrena ob- 



