T. S. Hunt—The Decay of Rocks. 201 
and we should expect to find it separated on reduction as rich 
sulphides, or as native copper. In accordance with this view, it 
was said in an essay on The Geognostical Relations of the 
The farther extension of this view to the Mesozoic 
sandstones of Connecticut, New Jersey and Pennsylvania, well 
<nown to be very often impregnated with copper disseminated — 
in the form of sulphides, sometimes associated wit organic re- 
mains, is obvious. It is to be noticed that the strata in ques- 
tion are generally deposited directly upon Hozoic rocks, from 
the ruins of which they were formed, and tha these, in our 
hypothesis, furnished the dissolved copper from which the dis- 
Seminated ores were derived. If this view be admitted we 
have farther and independent evidence that the decay of the 
Eozoic rocks, with that of their contained cupriferous sulphurets, 
Was going on in that pre-Cambrian period in which the Kew 
nee Series was accumulated, and was still active in Mesozoic 
ime, 
hese. The evidences of the pyritic origin of many of these 
vik dae (§ 24), 
amely, their association with unchanged pyrites. An exam- 
‘ 
ple of this is seen in the so-called copperas mine at Breinigs- oe 
% Proc. Amer. Inst. M. Engineers, i, 341. 
8 Azoic Rocks, pp. 201-203. 
