MINERALOGY OF THE OCHILS. 



IS 



V. Slate-Clay, 



Thin seams of a bluish-grey Slate-clay, posses- 

 sing the common characters, occur both above 

 and below the limestone, separating it from the 

 grey sandstone. 



VI. Claystone, 



This is a very abundant rock, and some very 

 beautiful varieties of it occur in the course of the 

 Ochil Hills. At Lucklaw it appears to pass into 

 basaltic clinkstone; below Birkhill f , it alter- 

 nates with sandstone, tuff and felspar, passing on 

 the one hand into the grey sandstone, and on the 

 other, through all the varieties of tuff and clink- 

 stone, to the perfectly compact felspar. It is also 

 found between the Yetts of Muckhart and Alva, 

 below the clinkstone, with which it probably al- 

 ternates. 



It is fine-grained, having a large flat eonchoidal 

 fracture, and an uneven cross fracture. It occa- 

 sionally contains scales of silver-white mica, parti- 

 cularly where it alternates with the sandstone and 

 tuff, as it does below Birkhill. The colour is 

 various, even in the alternating strata ; the most 

 common, however, is between pearl grey and isa- 



* This is a small hill between Cupar and Parton Craigs. 

 f An eminence about five miles to the westward of Wooii« 

 haven. 



