176 



At Gilmerton, near Edinburgh, and at Loanhead, about two miles 

 south-west of Gilmerton, they have a continual change of strata, 

 on account of their great declivity, which is about the angle of 45. 

 The number and variety actually cut through in this field is so im- 

 mense, that it would fill a large book to enumerate and describe 

 them all. They are all, says Mr. Williams*, whose work is replete 

 with the most interesting and useful information, what are commonly 

 called coal metals, that is, such strata as are generally found to 

 accompany beds of pit coal ; and there are above sixty strata, or 

 beds of c*oal, thick and thin, cut through at Gilmerton, in this 

 noble section : among which about twenty of them have been worked 

 at Gilmerton, and the neighbouring coal fields. The rest are thin, 

 though regular strata of coal, generally from about two feet, to three 

 or four inches thick ; and some of them, though regular strata, not 

 above one or two inches. In short, the strata cut through in this 

 great section contain such an amazing number and variety, that they 

 may be considered as a very complete assemblage, and example, of 

 all the strata which accompany coal, excepting regularly figured 

 basaltes, of which there are none at Gilmerton, though they have 

 cut through several beds of whin, of various colours, which approach 

 the quality of that stone. 



The substances which in general accompany coals demand also 

 some attention. Among these may be first noticed metallic sub- 

 stances : thus Valerius Cordus f relates, that, with the bituminous 

 coals which are dug near Cunharden, there also exists a bituminous 

 vein of copper and of silver; but iron is the substance most fre- 

 quently found. Sulphur is also found to abound almost universally 

 in pits of coal. Neither of these substances are, however, thus 

 found in a state of purity, but are generally combined together in 



* Williams's Mineral Kingdom, vol. i. p. 41. 

 t Valerii Cordi Observationes, &c. p. 217. 



