JAMIESON PLEISTOCENE, ABERDEENSHIRE. 



515 



1858.] 



up to a weight of about a ton and a half, and of a mineral character 

 similar to rocks which occur further up the valley. 



• Fig. 3. — Section at Collieston Coast-guard Station. 



a. Clay. b. Sandy strata. c. Gneiss. 



About a couple of miles to the north of the River Ythan the 

 sandy beach gives way to a rocky coast of gneiss and mica-schist, 

 which continues without interruption to the Bay of Cruden, a dis- 

 tance of more than five miles. These cliffs very commonly present 

 a face from 60 to 100 feet high towards the sea: where the rock 

 itself attains this elevation it is generally destitute of superficial 

 covering, or has sometimes a thin layer of coarse clay ; where, 

 however, the rock sits low, the additional height is made up of 

 grassy banks, which appear to be composed of red clay and sand, 

 stratified, frequently in an undulating manner. Owing to the grassy 

 surface, the interior of these banks is seldom disclosed by any good 

 section. At the Collieston Coast-guard Station (fig. 3), however, a 

 slip has laid the mass open from top to bottom, showing — 



Feet. 



1. Red clay, devoid of stones, but without any strati- 



fication-lines apparent 17 



2. Strata of the finest sand, varying in colour from 



pale brownish-grey to reddish 56 



3. Gneiss-rock, covered by a foot or so of its own 



debris 30 



The sandy strata lie horizontally with some gentle undulations: 

 they are quite devoid of all stones, pebbles, or coarse gravel. In 

 some small seams of coarser sand, near the bottom of the mass, I 

 found traces of broken shells, but so comminuted as to render any 

 knowledge of the species unattainable. The junction of the clay 

 and sand forms a line nearly horizontal ; and the sea-waves wash the 

 foot of the rock. 



At a cliff, a mile or so to the north of Collieston, some slips show 

 that the gneiss is covered by 30 or 40 feet thick of strata, composed 

 almost entirely of fine sand varying in hue from red to grey. Some 



