Mr. Webster on the Strata lying over the Chalk, 171 



in Dorsetshire, is horizontal, differing in this respect from their 

 position in Alum bay. There must, therefore, have been some 

 twist in the chalk stratum, a remarkable instance of which I dis- 

 covered at the other end of the chalk range beyond Lulworth.* 



Since I shall have a future opportunity of making some remarks 

 on the very singular stratification of these places, I shall only at 

 present observe, that the highly inclined chalk from the Culver cliffs 

 at the east end of the Isle of Wight to White Nose, in Dorsetshire, 

 5 miles west of Lulworth, formed the southern side of this depression 

 in the chalk stratum. The north side of it may be traced in that 

 range of hills called the South Downs, extending from Beechy Head, 

 in Sussex, to Dorchester, in Dorsetshire. The strata of which 

 these hills are composed, dip generally from 15° to 5° to the south ; 

 the inclination varying in different places. The south side of the 

 basin therefore must have been extremely steep, while the slope 

 of the north side was very gentle. The closing of this basin at the 

 west is obscure, and cannot be distinctly traced j but the east is now 

 entirely open, the sea passing through it. 



Ilf. Extent of the London Basin, 



This extensive basin, like that of the Isle of Wight, Is probably 

 owing to a depression in the chalk stratum. 



Its south side is formed by a long line of chalk hills. Including 

 those of Kent, Surrey, and Hampshire, called the North Downs, 

 extending through Basingstoke to some distance beyond Highclere 



* The drawings and description of this, as well as of many other parts of this 

 remarkable coast, will be found in the above-mentioned work now preparing for publi- 

 cation, by Sir 11. Englefiald, 



y 2 



