1883. 7 Trans. N. Y. Ac. Set. 



The specimens of the deposits of the geysers and hot springs of 

 the Park, exhibited by Mrs. Smith, are of two kinds ; one, silicious 

 (geyserite), from the geysers ; the other, calcareous, from the 

 " Mammoth Hot Springs." The first kind was produced by the 

 action of hot water on a siHcious volcanic rock (rhyolyte) ; the sec- 

 ond, on limestone, which underlies the northwest corner of the 

 Park. A third kind of deposit is seen in the " paint pots " and 

 "mud geyser" of the Norris basin, a pink or white clay, appar- 

 ently derived from the feldspathic portion of the decomposed rhy- 

 olyte, the quartz having been dissolved out. The clay in the paint 

 pots is sometimes highly colored, forming a pasty or semi-fluid 

 mass in a state of constant ebullition from escaping steam. The 

 deposit of calcareous tufa, from the Mammoth Hot Springs, is 

 quite rapid, coating objects, like the horse shoes and other things 

 shown, with a film an eighth of an inch thick, when they are im- 

 mersed in the water for two or three days. 



The President exhibited specimens of brilliant anthracite, 

 sent by Mr. M. C. Read, Corresponding Member of the Academy, 

 residing at Hudson, Ohio. They are reported to come from 

 Hastings Co., Canada, a region underlain by Laurentian rocks. 

 If this report is correct, they are probably the residue of the spon- 

 taneous distillations of petroleum, like the asphaltic anthracite of 

 the Calciferous sandrock of Herkimer, in New York, and of the 

 Utica shale at Canajoharie. 



Mrs. James Weld exhibited some peculiar crystals of carbon- 

 ate of lime from Fort Laramie, Wyoming Ter. ; hexagonal prisms, 

 I to 2 inches wide, :!■ to i^ inch in length, with bevelled edges ; the 

 form of aragonite, with minute and partial internal rhombic 

 cleavage of calc-spar — probably aragonite changing to calcite. 



Mr. N. H. Darton read a paper 



ON THE strata OF INDURATED SHALES BETWEEN BERGEN HILL 

 AND THE PALISADES, N. J. 



Prot. Daniel S. Martin then spoke on the subject of 



THE TRENTON (n. J.) GRAVELS, AND THEIR CONTAINED IMPLE- 

 MENTS, AS BEARING ON THE ANTIQUITY OF MAN. 



(Adsiraa.) 



After reviewing the general facts regarding prehistoric archaeology 

 abroad, as to the differences between palaeolithic and neolithic imple- 



