86 TRANSACTIONS OF THE [FEB. 18, 
ite-diorite is more applicable. It is similar in mineralogical 
composition to the granite-diorite described by Matthew from 
near St. John, N. B.,* and a quartz diorite described by Grims- 
ley from Cecil county, Md.+ 
That the Harrison rock has undergone a large amount of 
dynamic metamorphism is proved by the gneissic and schist- 
ose structure, the strained appearance of the minerals, undula- 
tory extinction of the quartzes and cracking of the feldspars. 
The formation of “Augen” and micropegmatite may also be 
added.{ The mica and hornblende which are often pitted with 
quartz show no such bending or breaking, and it seems not im- 
probable that they are of secondary origin, the result of a recrys- 
tallization of the rock. 
The age of the intrusion of granite diorite is somewhat a mat- 
ter of uncertainty. Mather, Dana and Merrill consider that 
the mica-schists into which the granite-diorite has been in- 
truded are of Silurianage. This would, therefore, make the rock 
of post Silurian age. It is evident, however, that it received its 
eneissoid structure during the period of metamorphism which 
affected the whole of Westchester county. 
No good contact between the schist .on the east and the gran- 
ite-diorite has thus far been found. It may be said, however, 
that near the boundary the schist is seamed with numerous 
veins of coarse granite and pegmatite. 
MINERALOGICAL LABORATORY, COLUMBIA COLLEGE. 
The paper was illustrated by maps and specimens and was 
discussed by the Chairman and Secretary. 
The second paper was by N. H. Darton and J. F. Kemp, “The 
newly discovered Peridotite Intrusion near Syracuse, N. Y.” 
The paper was discussed by the Chairman and Messrs. Kunz 
and Martin. It will be printed in full in an early number of the 
American Journal of Science. 
, 
Ten-minute remarks were then made by Professors Martin, 
Stevenson and Kemp, continuing the discussion of January 21st 
on the “ Condition of the interior of the earth.” 
*Trans. N. Y. Acad. Sci., Vol. XIII. 
tJour. Cin. Soc. Nat. Hist., July, 1894. 
{See K. A. Lossen—Ueber Gneiss-granit as Structur-abinderungen der Eruptiy- 
granit Giinge in Harzburger Gabbro, Zeitschr. d. geol. Ges,, XL., p. 780. 
