Professor J ameson mi the Black Lead of Ayrshire^ 1 
II. Black-Lead Mine near New Cumnock, Ayrshire. 
This mine is situated about four miles from New Cumnock^ 
in Ayrshire. All the strata of the district belong to that coal 
formation which occupies so great a tract of this division of ScoU 
land. The rocks are disposed in strata and beds, and agree in 
their general arrangement and connections with the other rocks 
of the secondary class. The strata which have been cut through 
in prosecuting the mining operations, and those which are natu- 
I’ally exposed in the neighbourhood, are the following, begin* 
ning with the uppermost, or that immediately under the soil. 
1. Sandstone. 
S. Slate-clay. 
8. Greenstone, with graphite. 
4. Slate-clay. 
5. Greenstone. 
6. Columnar glance-coal 
and graphite. 
7. Greenstone. 
8. Llinty-slate, 
9. Sandstone. 
We shall now describe them in the above order. 
1. — Sa7idstone. 
This rock is principally composed of concretions of greyish- 
white quartz, with a few scales of mica, and these are rather 
loosely aggregated. In some parts of the bed, the sandstone is 
disposed in globular and spherical distinct concretions, resem- 
bling those we observe in beds of greenstone and other trap- rocks. 
S. — Slate-clay. 
Immediately below the sandstone is a bed of slate-clay, from 
ten to twelve feet thick. This clay, in some parts of the bed, 
appears passing into a mineral, which some mineralogists name 
dinty-slate ; others, basaltic hornstone, or jasper, and which ap* 
peai’s to have some relatioif to compact felspar. 
S.- — 'Greensteme. 
The slate-clay rests upon a bed of greenstone, which is dis» 
posed in globular distinct concretions. It contains imbedded 
portions of graphite, which are often so intermixed, and im* 
ptegnated with the greenstone, as to pfove their eotemporaneous 
formation. 
L— Slate-Clay. 
The bed of greenstone is succeeded by one of slate-clay/ 
about twelve feet thick, which in some places passes into the 
jaspery or felspar rock. 
