568 ISLE OF MAN. GEOLOGY. BRECCIA. 



The obscurity which attends the different breccias that 

 accompany the limestone, renders it expedient to reserve a 

 separate paragraph for their description. 



No continuous beds of either of them can be traced ; 

 since even that one, of which the greatest extent is visible, 

 is much interrupted and confused, either in consequence of 

 the trap veins or from other causes. With respect to the 

 others, they are only to be seen occasionally, where their 

 inclined position causes their edges to appear on different 

 parts of the shore, or where they are detected by some 

 casual fracture of the ground. There is consequently 

 much difficulty in discovering their relations to the lime- 

 stone, which can only be deduced from careful comparisons- 

 of their internal characters and positions together, at the 

 several interrupted points where they appear. They seem 

 to admit of being divided into two classes, those which 

 are found below the limestone, and those which lie 

 above it. 



In describing the sandstone at Peel and at Langness, 

 it was shown, that although the schist and the limestone 

 are in some places separated by the conglomerate, in 

 others, the contact of these two substances is immediate* 



In these cases no breccia intervenes, but a sort of 

 approximation to one may be occasionally seen in the 

 numerous fractures of the limestone, afterwards filled up 

 by calcareous spar. In one instance, already pointed out, 

 this fracture becomes so complete, and the fragments are 

 separated by intervals so wide and so irregular, that a 

 perfect breccia is the result. 



Another similar substance, apparently intermediate, both 

 in position and structure, between the limestone and the 

 schist, is found at Derby haven, and in other situations 

 which it is unnecessary to detail. The basis of this is 

 calcareous, and it contains irregular fragments of schist 

 and quartz. Its analogy, both in position and in origin, 

 to the breccia of the red sandstone is obvious ; and it may 

 be conceived to be the evanescent edge of that rock. It 



