Professor Jameson on Seccmday^ Greenstmt and Wacke. 143 
9. Bituminous Shale, 
The thickness of this bed is about ten feet, and, like the 
other beds of this mineral, it contains layers of clay-ironstone. 
10. Wacke, 
The bituminous shale is again succeeded by a bed of wacke^ 
traversed by numerous small veins of calcareous spar, 
11. Bituminous Shale, 
The lower side of the preceding bed of wacke gradually 
passes into bituminous shale ; on the upper side also a similar 
gradation is to be observed. The wacke, as it approaches the 
shale, becomes slaty, and gradually exchanges the green 
colour for the brownish-black tint of the bituminous shale,- 
The bed is about three feet and a half thick.- 
12. Wacke, 
This bed is about eight feet thick. 
13. Bituminous Shale. 
The shale in this bed passes into wacke. 
14. Wacke, 
This bed appears to be from fifteen to twenty feet thick. 
Several other alternations of tvacke and bituminous shale 
occur still more to the eastward, when they are succeeded by 
beds of grey-coloured sandstone, which have the same easterly 
dip with air the other strata of the section. 
In this section, then, the lowest bed is porphyry, and the high- 
est sandstone. 
These different rocks, viz. the sandstoriej bituminous shale, 
clay-ironstone, wacke, and porphyry, are members of the same 
formation, and numerous transitions are to be observed from 
the one into the other. Thus the porphyry in different parts 
of the Caltonhill, passes into greenstone, the greenstone into 
wacke, the wacke, in the section just described, into bituminous 
shale, the shale on the one hand into sandstone, and on the 
other into clay-ironstone. These facts prove the simultaneous 
formation of these rocks, and thus shew that if wacke and 
greenstone are true volcanic rocks, the sandstones, shales, and 
ironstones with which they are associated, must have been form- 
ed in the same manner ; — a position which cannot be maintained' 
ki conformity with any of the present systems of volcanism,' 
