52 TRANSACTIONS OF THE [JAN. 7, 
Mr. RAnp replied that they are not found in the vicinity 
of Philadelphia, though he had paid less attention to the lime- 
stones, and did not like to assert positively. Carbonate of lime 
occurs in the gneisses and dolomite in the steatites, but rather 
as a rare mineral, in both cases, than as a constituent. 
Pror. D. 8. Martin spoke with high appreciation of the ob- 
servations of Mr. RAND, and said that he had looked forward 
to this meeting as one of much importance, hoping that it might 
mark a new departure in local studies of this kind. All that 
has been done in the region about this city has been for years 
past confined principally to local mineralogy. In that depart- 
ment a great deal of interesting work has been accomplished; 
but the geological relations of our crystalline rocks have received 
little elucidation. Our Philadelphia brethren seem to have 
gone further than we have; perhaps because the rocks there- 
about are better defined, or more readily accessible, than ours. 
It is very desirable that some movement for more systematic 
study should be organized. Why might not a plan be arranged 
by which local mineralogists and geologists all along the line of 
this belt of ‘‘ Atlantic” gneiss should co-operate in the study of 
its relations? Such aconnected scheme of working could hardly 
fail to yield important results in clearing up the geology of this 
much disputed region. 
Dr. N. L. Brirron expressed his great interest in the results 
reached and the hypotheses suggested by Mr. RAND, which he 
thought would in the main prove to be correct. He remarked 
that nearly all the rocks found by Mr. Ranp and his colleagues 
in the section described actually occur in the vicinity of New 
York, although they can nowhere all be seen in so small an area 
as the one described by Mr. Ranv. Indeed in the broad Lauren- 
tian area of Westchester County there are still additional kinds 
of metamorphic rock species of no little interest and significance. 
The serpentines, gneisses, mica-schists and hornblende-schists, 
and their contents, are evidently very similar, with local differ- 
ences such as we would naturally expect; there is more serpen- 
tine in the Philadelphia region and less crystalline limestone, 
none of the latter having been mentioned by Mr. Ranp. 
Dr. Britton regarded all these strata as portions of a single 
