108 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



sham beds, certain elements in common which seem to connect the two 

 deposits, by showing that, although no doubt derived from the waste 

 of two different lands, yet that they probably were deposited in the 

 same sea, as the sediments pass partially into one and the other area, 

 and have been to a certain extent subjected to the same disturbing 

 causes. Taking this formation in a horizontal plane, the changes 

 which it exhibits as it ranges from east to west in the Paris area are, 

 in a measure, progressive (although not in the same ratio) and in 

 accordance with the changed conditions apparent in the Hampshire 

 area. 



I must, in the first place, observe, that in the Barton series I would 

 now include the siliceous sands at the base of Headon Hill and at the 

 top of Barton Cliff. For, although they contain no organic remains at 

 those spots, casts of marine shells, apparently of the same species as 

 those in the underlying clay, occur in considerable numbers in parts 

 of the sands occupying the same position at White Cliff Bay ; whilst 

 at Barton, as the deposit ranges eastward towards Hordwell Cliff, these 

 sands alternate with fossiliferous grey clays, and form with them 

 passage-beds between the purely marine and compact Barton Clay 

 and the freshwater beds nearer Milford. I would therefore give, as 

 constituting the Barton series at the three places where it can be 

 distinctly recognized and measured, the following general sections. 

 They will serve to show the rapid variations to which this series is 

 subject even within this limited area, — the distance from Barton to 

 Alum Bay being six miles, and from Alum Bay to White Cliff Bay 

 twenty-one miles. 



1 . General Section of the cliff from High Cliff to Barton, on the 

 coast of Hampshire *. 



Feet. 



r Yellow and white siliceous sands, averages about 15 



I Grey sandy clay — with Avicula, Cardium, Oliva, &c. — 



b. -{ divided by a wedge-shaped bed of sand about 30 



I Yellow siliceous sands .,....*.. „ 30 



L Grey clayey sands — Chama,Pectunculi!S,Nucula,Szc. „ 20 

 Mass of compact bluish-grey clay with septaria; shells 

 dispersed throughout — Valuta, Fusus, Murex, Pleuro- 



toma, Cardium, Tellina, Corbula, &c about 150 



a. ■{ Grey clay, with seams of yellow sand and shells ... „ 20 



Grey sandy clay — Echini, Cassidaria, &c „ 50 



Mixed clay and green sand, impressions of shells ... „ 14 



Bed of flint-pebbles in sand, — size moderate „ 1 



330 



Or, resolving the mass roughly into its elements, we find it here 

 consists of — 



Siliceous sands, about 45 feet. 



Clays 285 ,, 



* For fuller details of this section, see Dr. Wright's paper in the Proc. Cottes- 

 wold Naturalists' Clul), vol. i. p. 129-133, 1853. 



