516 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 24, 



seams of pebbly gravel occur in several places, interstratified with 

 the fine sand in undulating layers. These gravelly seams contain 

 fragments of broken shells, amongst which I could distinguish the 

 hinge of the Cy prima Islandica, also bits of smaller Pectens and 

 pieces of a bivalve shell, ornamented with fine radiating striae be- 

 tween the growth-lines. Along with these shells there occur also 

 many small bits of grey and yellow limestone, which appear to have 

 been derived from secondary formations. 



All along the coast of Slains, the mass of sandy strata seems to 

 rest directly upon the gneiss-rock, without the intervention of any 

 other deposit. Sometimes the top of the bank consists partly of 

 fine red clay, occasionally interstratified with the sand. 



No large boulders are seen in these strata ; but large boulders 

 occur in the fields immediately back from the brink of the cliffs, 

 as if resting on the surface of the deposit. These blocks are of 

 greenstone, gneiss, and granite. 



Further north, towards the Bay of Cruden, the rocks get higher, 

 and the Pleistocene deposits retire from the cliffs, which are gene- 

 rally bare. The gneiss is thrown into long undulations, and gets 

 more contorted and altered in texture as it approaches the granite, 

 which first shows itself at the southern side of the Bay of Cruden. 

 At the bay itself the rocks disappear, and a low expanse of drifted 

 sand is backed by steep grassy banks, which appear to be composed 

 almost entirely of Pleistocene beds. These banks attain a height of 

 about 120 feet above high-water mark, presenting a steep front to 

 the sea. Their base is perhaps 10 or 12 feet above the sea-level. 

 No good section reveals the structure of these slopes ; but near the 

 top of one of them, about 5 feet of coarse red clay is seen rest- 

 ing on fine soft sand, of a reddish-brown tint, indistinctly strati- 

 fied, and quite free from stones. The clay shows no stratification- 

 lines, and contains pebbles of greenstone, granite, quartz, &c, more 

 or less rounded. I picked out one fragment about 5 inches long, 

 smoothed on one side, and covered with many striae in different 

 directions. Towards the northern side of the bay these banks appear 

 to have suffered denudation, and are much lower and more undu- 

 lating. A section, 18 feet deep, shows fine, soft, reddish sand, con- 

 taining several thin seams of red clay. Following up the Burn of 

 Cruden, deep masses of fine sand and clay appear to occupy the 

 ground on both sides ; and at Ardiffery we find the stream flowing 

 along the foot of steep banks about 130 feet high, and the ground 

 slopes up behind perhaps 20 feet higher, making a total height of 

 150 feet. These banks appear to be composed, to their very base, 

 of sand and clay. The stream here cannot be many feet above high- 

 water mark — perhaps 15 feet. No deep extensive section occurs ; 

 but slips in various places reveal the structure of the mass almost 

 from the top to the bottom. The lower part of the bank, to the height 

 of about 20 feet above the stream, is concealed by the low slope of 

 the ground, beyond which several small sections disclose regular 

 horizontal strata of very fine sand, mostly of a pale-grey tint, but 

 occasionally reddish. Amongst this sand there occur a few thin 



