Geology of the South-east of Devonshire. 



441 



with the shells of two or three species of Helix. At Slapton Ley, Swanpool, and other places, are 

 also raised marine beds passing into lacustrine ones, full of freshwater shells, which occasionally contain 

 layers of freshwater fishes, the remains of those which from time to time are destroyed by irruptions 

 of the sea, as in 1824 and 1836. 



Fig. 2. 



Sands with Helices. 



Raised marine beds. 



Baised marine beds- 



Actual beach 



Raised Estuary Deposits. 



§ 6. Raised marine beds. — A raised beech is seen a little on the inside of the 

 point of land known as Hope's Nose, which forms the eastern limit of Tor Bay. 

 From the rocks below, or from the sea, it has the appearance of a series of hori- 

 zontal and parallel beds ; and the view, fig. 3, taken from the east, shows the mass 

 as it rests on the highly inchned edges of the limestone. (See also PI. XLII. fig. 1 .) 



Fig. 3. 



Raised Beach at Hope's Nose. 



The distance between the usual line of high water and the lowest part of this 

 deposit is thirty-one feet ; and the thickness of the compact stratified portion is 

 seventeen feet. How far the beach extends upwards and inland, it is diflicult to 

 determine, as it is covered by an accumulation of shaly limestone derived from the 

 hill above ; but as, at an elevation of about sixty feet, there is a bed of sharp quartzose 

 sea-sand beneath the superficial debris, and as the point of land, previous to its eleva- 

 tion, must have presented a shelving coast, the marine beds would thin off gradu- 

 ally, and the greatest amount of elevation may be taken at about seventy feet. 



This deposit is not an uniform mass throughout : in the lowest part it is coarse, and contains blocks of 

 considerable size, and the shells of a large oyster occur in considerable numbers : higher up it becomes an 

 exceedingly hard, fine-grained, and compact sandstone; the shells in this portion are abundant and well pre- 



