Dikes near Lyon ML, X. T.—Eakle. 31 
Although the fringing gneisses of the Adirondack moun- 
tains are too far from our assumed base line to make any eon- 
elusions which will cover these latter rocks and ores, it can be 
safely assumed that the magnetites of the localities above de- 
scribed bear the same relation to each other as do the analo- 
gous deposits in New Jersey, that is. the Adirondack gneissic 
ores are of the same age. The attempt to correlate the two 
localities, New Jersey and the Adirondack region, is quite an- 
other matter. The most we can say is that the rocks and ores 
from the two localities are practically indistinguishable by 
any criterion which we are now able to establish, and that they 
are probably of the same age. 
In speaking of the Adirondack region, it must be remem- 
bered that in the labradorite rocks (noritesof Dr. Hunt) there 
are magnetites which in physical and chemical characteristics 
are wholly distinct from the gneissic ores described. The 
broad differences are as follows: 1st. The labradorite ores 
are titaniferous, often as high as 45 r /£ . and are. as a rule, non- 
phosphatic. 2d. The gneissic ores are non-titaniferous a< a 
rule, and are highly phosphatic in places and are never wholly 
free from phosphate. 3d. The norites are massive, only 
showing an occasional banded structure; the enclosing rocks 
of the gneissic ores are bedded and foliated, often approach- 
ing a schistose structure. 
Geological Survey <>;' Missouri, Feb. 15, 189S. 
ON SOME DIKES OCCURRING NEAR LYON MT., 
CLINTON CO.. N. Y, 
By Arthur 8. Eaklk. Cornell D Diversity. 
Within tile last three years many of the numerous dike-, 
which occur in the region of lake Chainplain and in the 
neighboring Adirondack mountains, have been studied by 
professors Kemp and Marsters, and their results have lately 
been published in abstract*. The writer, who accom- 
panied them upon their second trip to the region, during the 
*Kemp, J. F., and Marsters, V. F. The Trap Dikes in the Lake 
Champlain Valley and the neighboring Adirondacks. Trans. N. V. 
Acad. Sci., vol. xi, p. 13, 1891. Abstract. This paper describes the 
different types of dikes occurring in the region, and also cites many 
references to dike literature. 
