Geological Sodetij. 461 



A letter from James Curry, M.D. M.G.S. was read. 



In this letter Dr. C. describes a remarkably large speci- 

 tnen of nodular agate (exhibited before the Society) which 

 he conceives to point out a natural connection between agate 

 and the plasma of the ancients. 



The reaihng of Mr. Webster's paper "On the Fresh- 

 water Formations of the Isle of Wight, with some Observa- 

 tions on the Strata lying above the Chalk in England/' was 

 begun. 



The observations in this paper were in part suggested by 

 the recently published memoir of MM. Cuvier and Brong- 

 niart, concerning the strata in the vicinity of Paris, in which 

 they have described two marine and two fresh-water for- 

 mations alternating with each other, the whole lying above 

 the chalk, which latter rock has hitherto been very ge- 

 nerally considered as one of the most recent deposits. 



It is to Sir Henry Englefield that we are indebted for the 

 first observation of highly-inclined strata of chalk in the 

 Isle of Wight. 



A circumstance so material for the theory of the forma- 

 tion, or of the revolutions undergone by the more recent- 

 strata of the earth, demanded a leisurely and carefid sur- 

 vey, which was intrusted by Sir H. Englefield to the well- 

 known accuracy of Mr. Webster. The present paper is the 

 result of this inquiry. 



An elevated ridiie of hills runs through the Isle of Wight, 

 in a direction nearly E and W, from Culver Cliff to the 

 Needles. These hills are composed of strata sometimes 

 nearly vertical, but generallv forming an angle with the 

 liorizon of from 60" to sb°, dipping northward. The 

 strata consist of the upper and lower bsds of chalk, that is 

 the chalk with and without flints, covering the chalk marl ; 

 and these again are underlaid by calcareous sandstone with 

 subordinate beds of chert and lin)estone, clay and car- 

 bonized wood. To the north of these strata occur, at 

 Alum Bay, other vertical beds of sand and clay, one of 

 which corresponds in its fossils and other characters with 

 the blue c'ay containing aplaria, usually known by the 

 Xiame of the London clay. 



The whole series of vertical beds exhibits no marks of 

 partial disturbance: but it is evident, from the occurrence 

 of these very same beds in other parts of the country in a 

 nearly horizontal position, and from the impossibility of 

 some of them (consisting; of loose sand with water-worn 

 nodules of flml) being deposited in the vertical position in 

 vhich they arc at present, that the whole inass must have 



been 



