Association of American Geologists and Naturalists. 145 
Mr. J. D. Dana in reply to the reasoning of Dr. Beck re- 
-marked, that 
Dr. B. argued that the zeolites might have been formed by the action 
of the volcanic steam on the rock: if this be possible it will by no 
means account for the large geodes of chalcedony in these rocks, 
which, consisting of layer deposited in layer, and often occurring in 
stalactites, was evidently formed from aqueous solutions. He also re- 
marked that the numerous minerals of Vesuvius were not looked for 
in the recent eruptions, but in the older lavas of Somma, which had 
been exposed for some years at least to the action of moisture and other 
decomposing agents; and that as far as his observation went, lavas im- 
mediately after eruption do not contain hydrous minerals of any kind. 
To Prof. Beck’s remarks on the refrigeration of our globe, he replied 
that this theory of refrigeration must be admitted by those who believe 
in its once fluid state ; but it cannot be asserted that this gradual dimi- 
nution of temperature continued in progress till the recent period. Yet 
the diffusion of corals proves that the ocean was undergoing refrigera- 
tion in the tertiary period. The reef-forming corals do not grow where 
the winter temperature is below 66° F., and are in general confined 
between the latitudes 28° north and south of the equator. Yet we find 
coral rock on Porto Santo, near Madeira, where the water in winter 
often stands at 58°; and farther back in the tertiary period similar reef- 
forming corals occur in England, and in the oolitic period still farther 
north. Mr. D. alluded to a statement made by Mr. Couthouy at the 
meeting of the Association at Boston, that the limiting temperature of 
corals was 76° F., and took occasion to remark that Mr. Couthouy was 
indebted to himself (Mr. D.) for the views there advanced by him with 
regard to temperature limiting corals: and added that the temperature 
76° F. was a mistake by Mr. Couthouy for 70°, the limit fixed upon by 
Mr. Dana when the views were communicated by him to Mr. Couthouy. 
Prof. John Johnston of Middletown, Conn., observed that the 
erystals of beryl at Haddam, were singularly broken and distort- 
ed, in a manner similar to that mentioned by Dr. Beck as belong- 
ing to the crystals of apatite from Hammond, so well known to 
all mineralogists. 
Dr. C. T. Jackson \aid on the table specimens of metamorphic 
rocks bearing upon the question which had been started yester- 
day and continued to-day. 
They were from Pequawket Mountain in New Hampshire. ‘This 
mountain was upwards of four thousand feet high, consisting of a pe- 
culiar granite destitute of mica. It had burst through an argillaceous 
slate, which at the base of the mountain was broken up into Pcrene 
Vol. xiv, No. 1.—April-June, 1843. 1g hg 
