Vol. 51.] CRUSH-CONGLOMEKATES OF THE ISLE OF MAN. 577 



adhere in places ; but within this crust the rock, as petrological 

 examination has shown, is practically unsheared (see Mr. Watts 's 

 Appendix, p. 594). 



The southerly portion of these Narradale exposures lies well 

 within the line of strike of the main conglomerate-zone of Sulby 

 Glen, and in the intervening ground, about a mile in width, there 

 is sufficient evidence to indicate the direct continuation of the 

 structure in this neighbourhood. Farther to the north-west, 

 however, there is certainly an area of sandy slates with iinbroken 

 or very slightly broken bedding, which possibly represents the beds- 

 below the plane of brecciation in the crest of the supposed anticline. 

 The anticline appears to ' nose out ' before reaching Narradale, and 

 that stream probably flows almost wholly along the conglomerate- 

 belt. But neither here nor elsewhere is the evidence sufficiently 

 clear to justify absolutely positive statement as to the disposition 

 of the crush-material as a whole. 



Between Narradale and Glentramman the conglomerate extends 

 over the high grassy plateau in a band nearly as wide as the stream- 

 section just described, while the unbroken gritty flags and banded 

 slates occupy the slopes overlooking the plain. But in Glentram- 

 man and eastward from this point to the coast there is no such 

 widespread continuous development of the structure ; and the 

 exposures arrange themselves as a series of disconnected subparallel 

 strips or lenticles fading out rapidly at both ends. While this 

 arrangement is quite in keeping with the theory of a contorted 

 plane, it is also not opposed to the alternative view that the 

 structure may have been developed in original^ limited and isolated 

 patches along the limbs of a series of folds. 



A peculiarity in the arrangement of both the broken and un- 

 broken rocks may here be mentioned. It is that the orientation of 

 the rock-masses as brought out by the mapping is not quite normal 

 to the general dip, but approaches by several degrees more nearly 

 to a north-and-south course than the inclination of the bedding- 

 planes would indicate. The general strike thus makes an angle 

 with the general dip acute to the northward where the dips are 

 directed between north and west points, and to the southward on 

 the opposite side of the main axis of the Island. This angle, more- 

 over, is usually more acute for the gritty rocks than for the argil- 

 laceous masses. Of course the dips in beds so folded give no clue 

 to the true sequence of the strata, but I take it that they do 

 usually indicate the axis of the folds ; and the divergence of the 

 general strike from this axis seems to show that the rocks since 

 the primary folding have been affected on a broad scale by earth- 

 movements acting along new lines. 1 



In accordance with this arrangement, the general dip of the 

 contorted slates and flags in the upper part of the Sulby basin 

 being usually somewhat to the westward of north-west, the course of 



1 This is probably a point of prime importance in the stratigraphy of the 

 Island ; I am paying especial attention to all the evidence bearing upon it. 

 and hope to be able hereafter to deal more fully with the question. 



