24 Dr. Wright on the Geology of the Isle of Wight. 



passes into a firm rock, and is seen in situ in the southern 

 escarpment. It preserves the same angle of incHnation as the 

 Lymnsean limestone. 



At its origin, the first 8 feet of this bed is a pure sand rock 

 with thin seams of freshwater shells {Paludina, Lrjmnaa, Cyclas). 

 Below this the bed contains large oblong nodules, chiefly com- 

 posed of shells, mostly in a fragmentary state; from these I col- 

 lected — 



Paludina lenta. Planorbis rotundatus. 



Lymnsea longiscata. Melanopsis fusiformis. 



pyramidalis. Cyclas exigua. 



Planorbis euomphalus. 



The lower laminje of this bed contain greenish-coloured sands 

 full of Paludma. This bed changes its physical character in dif- 

 ferent parts of its course. In Headon Hill it is calcareous, and 

 contains a few angular pebbles with two layers of hard siliceous 

 nodules, one in the middle and the other at the bottom of the 

 bed. It is here likewise distinguished by the same group of 

 fossils. As it stretches across the Solent it forms that dangerous 

 reef called Warden Ledge, over which a buoy is anchored : it 

 measures about 20 feet. In Headon Hill escarpment this bed 

 admits of several subdivisions. 



No. 24. Olive-green clay, stiff and tenacious, with numerous 

 layers of Potamomya plana and Melania. It rises on the shore 

 to the north of Weston Chine, and can be traced in situ to a con- 

 siderable distance : measures 1 foot, and rests upon a band of 

 lignite, in which the vegetable structure is well preserved ; mea- 

 sures 6 inches. 



No. 25. Bluish sandy clay with few fossils in its upper part, 

 but full of Potamomya plana, Paludina and Lymncea below : mea- 

 sures 2 feet 6 inches. 



No. 26. Lymnsean limestone, No. 3, rises on the shore a few 

 paces north of Weston, forms a thin ledge at its origin, and con- 

 tains X7/mw«« and Planorbis in abundance: measures from 10 to 

 18 inches. 



No. 27. Dark olive-green, marly clay, rises below the prece- 

 ding Lymnsean limestone ; it contains seams of Lymncea, Palu- 

 dina, and Potamomya, which prevail most in the lower layers : 

 measures about 10 feet ? 



No. 28. Light-coloured calcareous marl. It caps No. 29, and 

 forms a ledge over which the water falls in Weston Chine; con- 

 tains Lymncea and Planorbis, and measures 9 inches. 



No. 29. Fine gray sand, rises on the shore about 120 paces 

 north of the boat-houses by Weston Chine. This bed is well 

 exposed in that ravine : measures 2 feet 4 inches, and is under- 

 laid by a band of lignite about 7 inches thick. 



