84. 



PROCEEDINGS OF THE GEOLOGICi^L SOCIETY. [DeC. ^ 



Thus these most distorted 

 cases require the same expla- 

 nation as the others, and can 

 be accounted for by supposing 

 them to have been subjected to 

 a pressure acting obliquely on 

 the shell and pressing it, as it 

 were, downwards and forwards 

 atthe same time. This pressure, 

 acting in a constant direction 

 upon shells scattered about 

 in different positions, has pro- 

 duced the variety of extrava- 

 gant forms which are to be 

 found at South Petherwin 

 Tintagel, and every other lo- 

 cality where fossils are found 

 in rocks much cut up by clea- 

 vage. The oblique pressure 

 may always be resolved into 

 the same two direct forces, Z) 

 one forwards along the plane 

 of cleavage, towards 

 the intersection of 

 the cleavage and the 

 bedding, the other 

 downwards in a di- 

 rection perpendicu- 

 lar to the cleavage. -^t 

 These are the direc- 

 tions of the compres- 

 sion and expansion 

 previously demon- ~ 

 strated. Mr. Phillips 

 has apparently al- 

 luded to this oblique 

 pressure in the pass- Z 

 age already quoted. 

 But the facts already 

 stated and others to 

 be brought forward, 2^ 

 show that his expla- 

 nation is not suffi- 

 cient to include the 

 variously complica- ^. 

 ted eases of distor- 

 tion. 



When the 

 ding and 



exactly coincide at 

 Tintagel, the shells 



bed- 



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 3YB9b io saBla at 



