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138 Association of American Geologists and Naturalists. 
ding as one or the other most abounded. Dr. Houghton, Mr. 8. 
S. Haldeman, Dr. Beck, and Geo. B. Emerson, E'sq., continued 
the discussion of the subject until the hour of adjournment. 
The hours of session were fixed from 9 A. M. to 14 P. M., and 
from 3 to 6 P. M. 
Afternoon session, 3 P. M.—Mr. J. D. Dana read a paper “on 
the analogies between the modern igneous rocks and the so-called 
primary formations, and the metamorphic changes produced by 
heat in tl iated sedimentary deposits.” The points attempted 
to be established in this paper were—Ist. That the schistose struc- 
ture of gneiss and mica slate is no satisfactory evidence of a sed- 
imentary origin, and is to be attributed solely to crystallization. 
2d. That some granites with no trace of a schistose structure may 
still have a sedimentary origin. 3d. That the heat producing the 
changes that are termed metamorphic, was not applied from be- 
neath by conduction from some internal source of heat; on the 
contrary it was through the heated waters of a surrounding ocean, 
which received their high temperature from the eruption itself. 
In other words, the metamorphic rocks so called are not hypo- 
gene, as explained by Mr. Lyell, but, to use corresponding phra- 
seology, epigene, or analogous to other rock formations, deposited 
__ and solidified on the surface of the earth. 
[As this paper by Mr. Dana is published entire in the present 
number of this Journal, (p. 104,) it is unnecessary to offer any 
eae 
~~ abstract here.] 
Mr. Dana’s paper gave rise to much oral discussion, among seV- 
eral members, as to the possibility of heating a stratum of water 
at the bottom of the ocean, without at the same time giving rise 
_ to powerful upward currents which diffuse and dissipate the heat. 
Prof. Espy said he had great difficulty in conceiving how the 
ocean could be heated to any extent in the way proposed by Mr. 
Dana, because of the disturbance of statical equilibrium in the 
Ocean, giving tise to currents which would diffuse the heat. 
Mr. W. C. Redfield said it was with reluctance that he entered upon 
this discussion, but in the course of it the assumption “had been made, 
and seemingly admitted on all hands, that water at the bottom of the 
ocean, if raised in its temperature by the outspreading of lava or other 
ed, must immediately leave the bottom and rise to the surface. This 
was not necessarily so. He would illustrate his position by what often 
occurred in so rare and mobile a fluid as the atmosphere, and woul 
