Dr. Wright on the Geology of the Isle of Wight. 23 



This limestone band is not uniform in structure throughout 

 its course. It is of a pale yellow cream colour in some places, 

 dense and compact or light and porous in others. It varies in 

 thickness from 3 to 6 feet, and its compact varieties are used for 

 building purposes. 



How Ledge is formed by this bed stretching under the Solent ; 

 and the rocks at Warden and Alum Point are foundered blocks 

 of Lymnsean limestone. It is very fossiliferous throughout its 

 entire course. The shells are beautifully preserved : as they 

 drop out of the rock they leave cellular cavities ; the interior of 

 the shell being filled for the most part with a more spongy 

 material than that which connects the individual fossils with one 

 another. 



It is impossible to describe the beauty of some of the rocks 

 lying at Warden Point, which a})pear to be httle else than a mass 

 of freshwater shells cemented together by a calcareous matrix. 



The elegant forms of the snow-white shells make a chaste 

 contrast with the yellow rock in which they are imbedded. With 

 a chisel and a light hammer the following specimens may be ob- 

 tained in great perfection : — 



Lymnsea longiscata. Planorbis euomphalus. 



fusiformis. lens. 



columellaris. rotundatus. 



pyramidalis. obtusus. 



minima. Bulimus ellipticus. 



maxima. 



I regard this bed as the uppermost of the lower freshwater 

 formation. 



No. 19. Fawn-coloured sandy clay, with bands of Paludina 

 unicolor in the upper layers ; the lower layers are not so fos- 

 siliferous : measures 6 feet. 



No. 20. Bluish gray sands, no fossils : measures 3 ft. 6 inches. 



No. 21. Blue clay with several seams of shells. Paludince and 

 Melaniee are very abundant, and fine specimens of Unio Solandri 

 are obtained in good preservation, together with bones of Palceo- 

 therium and Trionyx, and a profusion of small black seeds, Car- 

 polithes ovulum, Brong., C. thalictroides, Brong. It rises south 

 of Colwell Chine. A good section of the bed may be seen at 

 Warden Point : measures 2 feet 6 inches. 



No. 22. Striped clays, gray and bluish, with rich seams of 

 shells, in which Paludina and Melania are most abundant : mea- 

 sures from 6 to 8 feet. 



No. 23. Grayish white sand rises on the shore near Warden 

 Point, passes through the upper part of Weston Chine, and is seen 

 capping the hill south of that gorge ; it reappears again beneath 

 the Lymnsean limestone on the north side of Headou ; here it 



