118 GEOLOGY OF THE ISLE OF WIGHT. 



sufficiently shown in the measured sections of Alum Bay, ir 

 which locality they attain a thickness of about 250 feet. 



Section of the Barton Clay in Alum Bay* 



(Measured in April 1851.) 



Ft. In. 



Ferruginous dark-blue clay, selenite, fragments of univalve 



shells, numerous fossils - - - - - 24 



Pale and ferruginous yellow sandy clay, green in the upper 

 part. Lignite, Corals, Dentalium, Ostrea, Corbula, Pleuro- 

 toma common and of several species. (The pathway from 

 the chine to the beach cuts through the lower part of these 

 beds) 69 



Sands, pale yellowish colour above, green below. (A layer 

 of septaria occurs in this bed about 10 feet from the top, 

 containing pebbles and fragments of wood, and overlying 

 a band of small Hint-pebbles) - - - - 35 



Dark bluish-grey and ferruginous-brown sandy clay, con- 

 taining much selenite and lignite. Corbula abundant. 

 (A layer of septaria, 1 foot thick, occurs 5 feet from the top, 

 3 feet under which is a band about 2 inches thick of very 

 small pebbles of white quartz, with Shark's teeth. A 

 second layer of septaria occurs at 28 feet; and a third, 

 5 feet from the bottom of the bed. There is also a band of 

 fossils at 13 feet, and a band of lignite 10 feet from the 

 bottom) - • - - - . - 53 



Pale grey loamy sand, mottled with yellow, and thinly 



laminated - - - - - - -90 



Dark bluish-green clay, with numerous univalves and other 

 fossils. A ribbed Dentalium, Fusus longcevus, Valuta 

 spinosa. Solarium, Cardium, Natica (2 species), Fusus 

 pyrus, Rostellaria, Cancellaria, Pleurotoma, Mitra (small 

 species) -- - - - - -65 



Total - - 255 



The Rev. O. Fisher gives the following details of the base of 

 the Barton Clay (including 15 feet of beds) at this point :t — 



Dark-greenish, coarse, sandy clay. Crowded with Nummulina Prest- 



wichiana [now known as N. elegans']. 



Rostellaria ampla. Strepsidura turgida. 



^rimosa. Cassidaria ambigua. 



Murex asper. Ancillaria, sp. 



Typhis pungens. Pleurotoma turbida. 



Cancellaria, sp. conoides. 



Pyrula nexilis. plebeia. 



Fusus bulbus. , sp. 



carinella. Voluta athleta. 



— errans. depauperata. 



~ interruptus. maga. 



~ longaevus. nodosa. 



— Nose. Mitra parva. 



— regularis. Marginella, sp. 



— unicarinatus. Natica labellata. 



sp. Turritella irabricataria. 



* Another section, differing somewhat in details, will be found in Messrs. GardDcr, 

 KeepiniT, and Monckton's paper. Quart. Journ. Geol. Soc, vol. xHv. p. 600. 

 ■}• Quart, Journ. Geol. Soc, toI. xriii. p. 84. (1862.) 



