Vol. 56.] EARTH-MOVEMENTS IN THE ISLE OE MAN. 17 



whole a gentle easterly pitch, we pass eastward from the horizon 

 at which the limestone-flags are simply undulating to the place 

 where, at the foot of the low cliff, the sharp crests pass up into the 

 ash and present the appearance in cross-section of being inter- 

 calated with it. Between the crests, small ragged strips of limestone, 

 altered around the margins into chert, are crumpled into fantastic 

 shapes and entangled among the tuff. All these effects seem 

 necessarily to imply a general movement and re-arrangement of 

 the ash in its relation to its limestone-floor, and I see no alternative 

 to this conclusion. 



VI. Internal Structure of the Volcanic Series. 



Much that was previously inexplicable in the internal structure 

 of the volcanic rocks became clear to me when the character of the 

 displacement at the base of the series had once been grasped. 

 With this foreknowledge I found everywhere indications of local 

 displacement and readjustment ; the isolated patches of limestone 

 were seen to present features compatible with their having been 

 torn up from the underlying floor, like the strips at Scarlet and 

 Poolvash : the bands of vesicular basalt were observed to have been 

 bent into curves and often shattered into fragments ; and the finely- 

 laminated tuffs with calcareous bands were found to have suffered 

 fracture and step-faulting every few feet, or sometimes inches, and 

 even in this condition to occur only in limited blocks, breaking off 

 all round into a confused mass in which the laminated structure 

 was suddenly blotted out and replaced by a rude streaky arrange- 

 ment in the otherwise structureless ash. 



In the forthcoming Survey memoir I hope to describe and illustrate 

 these features in full detail, and meanwhile must be content to state 

 my conclusions in more or less general terms. The effects of the 

 movement are always intensified towards the limestone-junctions 

 and again, to a still greater degree, in the vicinity of the masses of 

 basalt. The laminated structure is rarely visible in the ash except 

 in places most remote from these, and is therefore best developed 

 in the middle portion of the outcrop, between Cromwell's Walk and 

 Close-ny-Chollagh Point. The accompanying section (fig. 3, p. 18) 

 of the foreshore about 200 yards south of the last-mentioned place 

 represents what I believe to be the least disturbed portion of the 

 whole series. At the base of this section, the fine tuff containing 

 thin intercalations of cherty limestone is regularly and evenly 

 stratified, but is shaved off at a bedding-plane by a slide which 

 crumples and tears up the overlying strata bed by bed, producing 

 a confused agglomerate of ash and cherty ashy limestone in the 

 upper part of the section. 



The massive ridges of vesicular basalt, which occur principally 

 between Scarlet Point and Cromwell's Walk, are persistently 

 accompanied by coarse agglomerate, consisting of large subangular 

 blocks of the basalt (and sometimes also of cherty limestone) in a 

 streaky matrix of ash. While acknowledging the difficulty in 



Q. J. G. S. No. 221. c 



