76 PROCEEDINGS OF THE GEOLOGICAL SOCIETY 



January 31. 1844. 



Seymour Tremenheere, Esq., was elected a Fellow of this Society. 

 The following communications were read : — 



1. On the Thickness of the Lower Green sand Beds of the 

 South East Coast of the Isle of Wight. By F. W. Simms, 

 Esq., F.G.S. 



The last time the Green sand beds below the Chalk were the sub- 

 ject of discussion before the Society, great diversity of opinion was 

 expressed concerning the thickness of the group of beds denominated 

 " The Lower Green sand." To remove all doubt on this point, 

 Dr. Fitton proposed revisiting the south-east coast of the Isle of 

 Wight, and requested my co-operation in determining their thick- 

 ness. The following vertical section of the strata, seen in the 

 cliffs of the south-east coast of the Isle of Wight, and including 

 the three entire groups, viz : — 



i. The Upper Green Sand, 



2. The Gault, 



3. The Lower Green Sand, 



was made in company with Dr. Fitton, Mr. Mackeson of Hythe, 

 and the President of our Society, during a visit we made to that 

 coast in July last 



The horizontal line over which these measurements extended, 

 that is, from Atherfield point to the Cliff on the south of St. Ca- 

 therine's Down, is about three miles in length. Along nearly the 

 whole of this line, the coast is bounded by mural cliffs, except 

 where slips have taken place (and these are often of considerable 

 extent), and except where "Chines" (as they are called), that is to 

 say, deep precipitous gullies, worn by the action of brooks in the 

 argillaceous sands, open into the sea. 



Where the cliff was mural, and direct measurement was prac- 

 ticable, the thickness of a bed was taken by the tape or graduated 

 rod. Where direct vertical measurement was not practicable, as, 

 for instance, where the fall of the cliff had obscured the continuity 

 of the beds, the spirit-level was employed, as in ordinary engineer- 

 ing operations. Without the aid of that instrument it would have 

 been difficult, if not impossible, to carry on a connected series of 

 measurement over so long a base line with any tolerable degree of 

 accuracy. By the means employed, however, a series of vertical 

 measures was obtained, which I consider to be a near approxima- 

 tion to the truth. 



The apparent dip of the strata, as seen in the cliffs, and as 

 resulting from actual measurement, near Atherfield, was to the 

 east 2° ; but the true dip, as determined by the spirit-level at 

 Atherfield Point, where the rocks were bare at low -water, was 

 nearly south-east ; and its amount was found to be 2°. 



The junction of the Weald Clay with the Lower Green Sand is 



