1892. } NEW YORK ACADEMY OF SCIENCES. 21 
It is a curious fact that the porphyry and trap classed with 
the primary are described as penetrating the Utica slate, and 
that sienite of the Statified division is also said to occur in 
dikes. After achapter on the ill-starred Taconic system, the 
counties are taken up in order and described. In discussing 
the primary system, Emmons says little of the respective ages 
of the subdivisions, but he saw clearly the contrast of the 
“‘oranite’’ (7. e., the labradorite-hypersthene rocks) and the 
gneiss. It must be remembered that he worked in a wilder- 
ness and, considering his opportunities, he deserves the highest 
praise. He writes with extraordinary ability and clearness, 
and though, for instance, we have no confidence to-day in the 
igneous character of his limestones, we must realize that con- 
ceptions and knowledge of metamorphism have greatly 
advanced since his time. 
The dearth of papers in the next thirty or forty years is 
remarkable. The Canadians had country of much the same 
character to deal with, and the problem of the subdivision of 
the old crystalline rocks was attacked by them. The Adiron- 
dacks are often referred to, but no detailed field-work was done 
inthem. The relations of the gneisses, the norites or anor- 
thosites and the crystalline limestones have been and are the 
problems meriting attention. As is well known the gneisses 
were generally called Lower Laurentian, and the norites, Upper. 
A number of papers remain to be noted, which treat of 
restricted parts of the subject. The late Dr. T. S. Hunt 
published in 1871, a valuable contribution on the Mineralogy of 
the Laurentian limestones (21st Annual Report N. Y. State 
Cabinet, p. 47, 1871), but has comparatively little to say of their 
geognostic relations, James Hall presented to the American 
Association at the Buffalo meeting, 1876, a paper on the Age 
of the Serpentinous Limestones of Northern N. Y. It was 
published in the Buffalo Courier, Aug. 25th, and from this was 
abstracted for the American Journal of Science of October of 
the same year. Professor Hall regarded the limestones as later 
than the Laurentian and earlier than the Potsdam, but whether 
Huronian or not he does not say. The paper is rather general 
in character and gives no actual sections or data of localized 
character, at least in the printed abstract. 
In 1877 Dr. Albert R. Leeds published a paper entitled 
“Notes on the Lithology of the Adirondacks” (Chemical 
News, Mar., 1877; 36th Ann. Rep. N. Y. State Cabinet, 1877, p. 
79). Dr. Leeds’ material came mostly from the Keene Valley 
and consisted of varieties of norite and of several diabase dikes. 
Very careful chemical analyses are given, and some microscopic 
