DEIFTS OF THE VALE OP CLWTD. 



85 



It is of great importance for our present purpose to inquire what 

 is the character of this drift where it abuts against the rock along 

 the flanks of the hills that bound the vale. The clearest section is 

 that seen in the large limestone-quarry by the road north-west of 

 the old British camp of Parcymeirch, near the village of St. George ; 

 here a well-washed sand and gravel abuts against a steep slope of 

 weathered limestone, as shown in the section, fig. 4. 



Pig. 4. — Section in Quarry near the Village of St. George. 

 (Scale 30 feet to 1 inch.) 



A. Mountain Limestone, dip 20° N.N.E. 



B. Sand and gravel. 



C. Reddish boulder-clay, with fragments of sea-shells and scratched 



stones. 



D. Talus. 



In this section it is quite clear that a boulder-clay has filled up 

 an embayed corner in the limestone, and that a sand and gravel 

 swept down the ravine, perhaps into the sea, has caught against 

 the projecting mass, covering the crags and the clay-filled hollows. 

 The process of quarrying has left a thin wall of limestone in front 

 of the gravel and underlying clay -drift, the removal of which in 

 one place gives the appearance of a drift-filled fissure. The red 

 colour of parts of this clay may have been derived from the decom- 

 position of the limestone in which it occurred, and not from the New 

 Red. 



Further west still, at Colwyn Bay, variable deposits of sand, 

 gravel, and clay occur at various levels up the flanks of the hills. 

 From some of these, at a height of about 120-150 feet above 

 the sea, Air. Alfred Walker has collected the shells given in 

 column II. of the Table, p. 93. 



All, except Astarte borealis, are now found upon our coasts (see 

 Jeffreys's Brit. Conch, vol. ii. p. 320). 



