Professor J ameson m Secmdary Greenstme and Wacke. 1 S9 
hypotheses. The quarry from A to B is about four yards deep. 
The strata dip to the east under angles varying from 15° to 
20°, and are perfectly regular and parallel throughout their 
whole course. The beds and strata are of greenstone^ wackcy 
slate-clay^ and quartzy sandstone^ which mutually pass into 
each other, and thus form a perfect whole, the series not being 
interrupted by any foreign beds or veins. The most important 
of these rocks is the Greenstone, which exhibits the following 
characters. Its colour is bluish-green, very imperfectly crystal- 
lized, with imbedded crystals of augite, so that it is sometimes 
porphyritic. It is traversed by small veins filled with calcare- 
ous spar, quartz, and heavy spar. Some varieties of it, from 
the earthy aspect of the mass, and its containing cotemporane- 
ous angular and roundish portions of harder greenstone, appear 
passing into trap-tuff. There are two beds of this rock in the 
quarry, an uj)per and a lower. The upper bed is two feet and 
a half thick, and preserves the same thickness throughout the 
whole quarry, and is, in every respect, equally regular with the 
beds of sandstone and slate-clay. In some parts, the bed is 
more highly crystallized towards the middle than on the lower 
and upper sides. On the lying ov under' side, it passes into a 
very distinct and beautifully marked variety of greyish-green 
coloured Wacke, which is about five inches thick, a^ Fig. % 
Plate III. This wacke gradually passes into a reddish-brown 
clay, about six iiiches thick, which, in its lower part, is slate- 
clay, 5, Fig. % 
On the hanging or upper side of this bed of greenstone, 
there is a bed of quartzy sandstone ten inches thick, c. Fig. 2., 
which in some parts has a splintery fracture, glistening vitreous 
lustre, and considerable translucency, and this is one of the va^ 
rieties named Indurated Sandstone by the Plutonists. Interpos- 
ed between this sandstone and the greenstone, there is a thin 
seam or layer of greenish-grey coloured slate-clay; over this 
bed of quartzy sandstone is a bed of greenish grey-coloured 
slate-clay, about nine inches thick, d, Fig. 2. ; this has 
resting upon it a bed of quartzy sandstone, in many parts 
equally hard with that wdiich is nearest to the greenstone. 
Over these are alternations of beds of slate-clay and quartzy 
sandstone, in which the sandstone has often the same highlv 
