of the Neighbourhood of Edinburgh, 86l 
teresting manner, the chemical formation of conglomerated 
rocks. 
In various parts of the hill, which have been quarried at dif-^ 
ferent times, masses of grey sandstone occur imbedded in the 
rock. These vary in magnitude from a few inches to several 
yards in length, breadth, and thickness. They differ also in 
form, being either sharp angular, blunt angular, tabular, or 
disposed in beautiful arches. When digging the foundation of 
the Waterloo Hotel, a fine section was cut in the greenstone-rock, 
in which were seen highly inclined beds of slate-clay, supporting 
several arched strata of sandstone, and inclined straight strata of 
slate and greenstone, and the whole included in the mass of 
greenstone. 
The imbedded sandstone is sometimes intermixed with the 
greenstone or porphyry at their line of junction, or the whole ^ 
mass of the sandstone is coloured green, owing to the diffusion 
of the matter of the greenstone. In many of the quarries formerly 
open, and in others still exposed on the hill, some varieties of 
greenstone are quartzose, owing to disseminated quartzy par- 
ticles ; and, on the other hand, some sandstones are so highly 
impregnated with greenstone, as to appear intermediate between 
sandstone and greenstone. These appearances are in favour of 
the doctrine of the simultaneous formation of the greenstone 
and sandstone rocks. 
Some observers may be of opinion, that these masses of sand- 
stone have been broken from previously existing strata, and af- 
terwards included in the greenstone and other felspar rocks of 
which the hill is composed. The general diffusion of the matter 
of the greenstone through the sandstore, of the quartzose mat- 
ter through the greenstone, and the natural arches of sandstone 
associated with slate-clay, and inclosed in the greenstone, appear 
to us to favour the opinion of the simultaneous crystallization of 
the two rocks. 
3 . 
Veins of various descriptions intersect the rock in many direc- 
tions. These are of greenstone, calcareous-spar, limestone, agate, 
red jasper, and iron-pyrites. The greenstone veins vary from a 
few inches to three or four feet in width, and sometimes termi- 
1 
