Geology of High Teesdale. 193 
firmed by the presence of volcanic rocks along the whole escarp- 
ment of the calcareous chain*. I cannot help regarding these 
prolonged masses of trap, as the broken ends of the great levers 
which nature employed in severing the metalliferous beds, and 
bringing the chain of Cross Fell to its present elevation. In 
this point of view, we must consider the intrusive rocks which 
have so much modified the structure of High Teesdale, as origi- 
nating in a system of disturbing forces, which have acted, perhaps, 
simultaneously, upon all that portion of the great calcareous 
chain which stretches on the north-east side of the valley of 
the Eden. 
Whatever may be thought of these speculations, the facts 
detailed in the previous Sections of this Paper, still retain their 
importance, and, as far I comprehend them, completely esta- 
blish the volcanic origin of the trap rocks, associated with the 
mountain-limestone formation 11 High Teesdale. 
* The Reader may form a general notion of the extent of the trap, by consulting 
Mr, Greenough’s Geological Map. 
Vol. II. Part I. Bes 
