394 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 24, 



merate will be found rapidly thinning out, and tlie rest of the bed 

 composed solely of sandstone of uniform texture without any trace of 

 conglomerate. (See fig. 2.) 



Fig. 2. 



In the highest part, however, of this deposit, the strata are almost 

 entirely composed of conglomerate, and its thickness appears to in- 

 crease considerably as it proceeds in a south-west direction. 



At the Craigs, a short distance above the Craigs quarry, the con- 

 glomerate is met with in its greatest development. In this locality 

 three bold headlands occur presenting lofty fronts and perpendicular 

 escarpments to the east, and from this circumstance the locality de- 

 rives its name. These consist almost exclusively of the coarse con- 

 glomerate, and are so nearly related to each other that a geological 

 description of one will also apply to the other two. 



Mid Craig is situated about three hundred yards due west from 

 Craigs quarry, and under this craig the rocks of the quarry dip. 

 The lowest portion of it visible consists of a coarse light-red sand- 

 stone, which in some places is fully five feet in thickness. The 

 depth of this sandstone and the nature of the rocks which underlie 

 it cannot be ascertained, owing to the debris which occurs at the base 

 of the Craigs. The sandstone is succeeded by a bed of conglomerate 

 about five feet in thickness, and in this conglomerate layers of sand- 

 stone are met with rarely exceeding six inches in depth, which thin 

 out very rapidly and again occur at different positions in this bed. 

 A stratum of sandstone about a foot in thickness succeeds this con- 

 glomerate, and appears to increase in thickness in the direction of its 

 dip, which is similar to that of the sandstone at Craigs quarry. Al- 

 ternate beds of sandstone and conglomerate more or less similar to 

 the foregoing occur for a considerable height, until the sandstone 

 disappears and uniform beds of conglomerate alone are met with. 

 The thickness of these conglomerate beds varies considerably, and 

 even some of the individual beds differ greatly in thickness at dif- 

 ferent places. 



The fragments which compose the conglomerate consist principally 

 of whin, both slaty and compact, beside which some portions of sye- 

 nite and granite are also to be met with. These fragments are all 

 angular, and devoid of the slightest trace of friction or abrasion of any 

 kind. In size they vary from a small pea to about six inches in dia- 

 meter, and some occur much larger, but on an average about a cubic 

 inch is the size of the greater proportion of the fragments. They are 

 cemented together by a matrix of fine sandstone which is somewhat 

 similar to that occurring in the Craigs quarry. 



