THE 
AMERICAN GEOLOGIST 
Vol. I. JUNE, iSSS. No. 6. 
SOME AMERICAN NORYTES AND GABBROS. 
Geological notes from the laboratory of Denison University. 
1. 
BY C. L. IJERRICK, E. S. CLARKE, AND J. L. DEMING. 
The material for this paper was gathered in various parts of 
the United States and Canada, the species selected for descrip- 
tion being chosen for their supposed bearing on the genesis of 
this family. The norytes and gabbros constitute a very inter- 
esting group which may be regarded as forming a link between 
the diabases and basalts on one hand and the diorytes and other 
paragenous eruptives on the other. / 
The view held by the senior writer that older eruptives are 
to be classed in one or other of two groups, depending on the 
method of origin, has already been foreshadowed in a paper in 
the second volume of the bulletins of Denison University'. All 
the older eruj^tives which arc apparently independent, so far 
as composition is concerned, of the influence of the interpene- 
trated rocks are termed A7itogenous eruptives. Illustrations 
are afforded by ordinary diabases and basic gabbros and norytes. 
The remainder of what are commonly known as basic erujDtives, 
which show in their composition the obvious effect of the 
country rock, are termed faragenous eruptives. And, how- 
ever much the texture may vary in each of these, it is claimed 
that they constitute rather shai-ply and naturally distinguished 
assemblages. The paragenous species may assimilate closely 
to the wall rock or may resemble very nearly the parent auto- 
genous species. The diorytes are of this nature, at least in 
