Vol. 56.] EARTH-MOVEMENT IN" THE ISLE OF MAN. 



19 



relative abundance is clearly influenced by the character of the 

 masses in their proximity. 



The following diagram has been prepared to illustrate my view 

 in regard to these structures, and will also serve to elucidate the 

 subsequent paragraphs. 



Fig. 4. — Diagram illustrating the supposed general result of earth- 

 movement in the Volcanic Series east of CromwelVs Walk: a 

 disrupted anticline of rigid lava pushed northward along a 



thrust-plane. 



%&%& 



A = Volcanic ash, much disturbed, but showing traces of original bedding. 

 xA = Rearranged volcanic ash ; a = Vesicular basalt ; b = Strips of limestone 



carried up along thrust-planes. 

 xa = Coarse agglomerate of vesicular basalt-blocks in an ashy matrix ; 

 xab = The same, with some limestone-blocks. TT = Thrust-planes. 



If my reading be correct, it follows that all the anomalous 

 phenomena exhibited in the outcrop of the Manx Carboniferous 

 volcanic rocks at present above sea-level may be explained as the 

 result of earth-movement upon a belt of strata consisting 

 of limestone passing up into stratified submarine tuff, with inter- 

 bedded lava-flows and possibly sills or dykes in the eastern part 

 of the exposure. 



VII. General Character of the Disturbances. 



Although my previous work among the Manx Slates had en- 

 lightened me as to the potentiality of earth-movement in disorganizing 

 original stratification, I was not prepared to find that such results 

 could occur with so little modification of the rock-substance as 

 presents itself in the Volcanic Series. 



In the crush-conglomerate of the Slates, the shearing has been 

 intense ; the rock-fragments have been dragged out into phacoids; 

 strain-slip cleavage has been magnificently developed in every part 

 of the mass ; and in tracts adjacent to the belts of disruption, 

 though the original bedding may still persist, the rocks are packed 



c2 



