76 Mr. Forster's Observations on Ratcheugh Crag. 



the basset of the latter. This pit is in a situation where the strata may- 

 be considered in their regular position. 



SECTION AT DUNSHEUGH PIT. 



Feet. In. 

 Bed of carboniferous Limestone (cropping out from under the Basalt, 



with a few feet of intervening Shale) about 15 



Coal, varying from 4 to 8 inches, say 6 



Shale, 33 



Sandstone, 15 



Bed of Shale, containing an abundance of bivalve shells (Producta 



castata), 6 



Bituminous Shale (variable), 3 



Coal (divided by a 10-inch band of bituminous Shale), varying from 



1 foot 8 inches to 2 



Total, 69 



(Or Hi fathoms.) 



At a very short distance to the west of this pit may be seen evident 

 traces of a Basaltic Dyke. It is to this Dyke, which will intersect 

 Ratcheugh Crag, nearly at a right angle with its range, causing a breach 

 of about three hundred yards in width, that I attribute the remarkable 

 diiference exhibited in the sections of Ratcheugh Crag and Snableases 

 Quarry. The following rough sketch will convey a sufficiently accurate 

 idea of the relative situations of these two points. 



S. W. CORNER OP SNABLEASES 



RATCHEUGH CRAG. QUARRY. 



.a 



Openmg ot' about SOO Tfards throng Tiffith. 

 the I)y^ is supposed to pass. 



a. The point at which the section was taken, b. Carboniferous Limestone, c. Columnar Basalt. 



It presents a view of the face of the Cliff to the westward ; Snableases 

 Quarry being situated a little further to the dip than Ratcheugh Crag, 

 and, from its range, partially representing the dip of the strata ; whereas 

 the face of Ratcheugh Crag ranges nearly in the drift, or water level 

 course of the strata. 



The section of the strata of which Ratcheugh Crag is composed Csee 



