BAGSHOT BEDS. 



445 



hill, and it owes its preservation to the induration of the sands. ^ (See Fig. 54, 

 p. 347, and Fig. loi.) A smaller rock known as the Puckstone occurs on a 

 neighbouring hill. The red and crimson sands of Alum Bay, etc., are coloured 

 by peroxide of iron ; there are coloured sands in the Lower Bagshot Beds, and 

 also higher up in the Bracklesham Beds. Creech Barrow (see Fig. 71) is a conical 

 hill of Lower Bagshot Beds, rising to an elevation of over 600 feet, and situated 

 to the west of Corfe Castle. 



' iMf ^1 



^' 



Fig. 75. — Clay Pit, near Corfe Castle, Dorsetshire. 



Middle Bag^shot Beds. 



In the Hampshire Basin these beds have been found to admit 

 of two divisions: — 



2. Barton Clay. 



I. Bracklesham Beds. 



The series is represented by the lower division (Bracklesham 

 Beds) in the London Basin. Its thickness has been estimated at 

 410 feet in Alum Bay, and 710 feet in Whitecliff Bay. 



Bracklesham Beds — The Bracklesham Beds were so named 

 because the strata are displayed at Bracklesham Bay in Sussex, 

 where their position was defined in 1847 by Prof. Prestwich.^ 

 According to the Rev. O. Fisher, they consist of alternations of sand 

 and sandy clay, the clays being more prevalent in the upper part, 



^ Prestwich, Geologist, i. 1 13. 



^ Q. J. iii. 354, X. 435 ; Fisher, Q. J. xviii. 69 ; C. Evans, P. Geol. Assoc ii. 

 153; Etheridge, Address Geol. Sec. Brit. Assoc. 18S2. 



