332 Scientific Intelligence. 



II. Geology and Mineralogy. 



1. Notes on the meeting of the Geological Society of America 

 at Indianapolis. (From a letter to one of the editors.) — The 

 summer meeting of the Geological Society was held on Tuesday, 

 Aug. 19, Vice-President Alexander Winchell, in the absence of 

 Prof. Dana, taking the chair. Eight papers were read in the 

 course of the three sessions of the day. Mr. W J McGee gave 

 an account of the Appomatox formation in the Mississippi enibay- 

 ment. He admitted that the formation traced to the Mississippi, 

 became identified with the Lagrange formation of Safford and 

 was equivalent also with a part of the Orange sand of Hilgard. 

 Dr. Safford, who was present, expressed his willingness to surren- 

 der the name Lagrange; but it was questioned by others whether 

 the law of priority should not hold. 



Prof. C. H. Hitchcock gave an account of the Redonda phos- 

 phate occurring on Redonda, one of the Leeward islands of the 

 Caribbean sea — first described and analyzed by Prof. C. IT. Shep- 

 ard (American Journal of Science for 1869 and 1870), making 

 it a hydrous iron-alumina phosphate. He stated that it overlies 

 and penetrates irregularly a basic lava, and is interstratified 

 with it. It was originally covered with a bed of guano. Prof. 

 Hitchcock expressed the opinion that it was of igneous origin, 

 which was contested by Mr. N. H. Winchell, who regarded a 

 guano origin as most probable. Mr. E. W. Claypole presented a 

 paper on "The Continents and the deep seas." 



Prof. C. L. Herrick discussed "The Cuyahoga shale and the 

 Waverly problem," distinguishing three horizons in the Waverly 

 — the upper corresponding to the Keokuk and Burlington ; the 

 middle, to the Kinderhook ; and a lower represented by the Berea. 

 The Bedford shale was made Devonian. — N. H. Winchell pre- 

 sented a paper on the Taconic area of Minnesota and western 

 New England, making out five horizons of iron ores in Minnesota 

 — namely, in descending order, (1) The hematite and limonite of 

 the Mesabi, represented by the Penokee-Gogebic Range, the ores 

 originally iron-carbonate ; (2) Titanif erous magnetite, associated 

 with the great Gabbro range ; (3) Siliceous magnetite, at the base 

 of the gabbro ; (4) The hematite and magnetite of the Kewatin, 

 as at Vermilion Lake and Ely ; and (5) The ores of the crystalline 

 schists. 



Prof. H. S. Williams discussed the question — What is the Cai*- 

 boniferous System ? Mr. A. Winslow described the Geotechtonic 

 and Physiographic geology of western Arkansas. 



Mr. McGee read a paper by Lawrence C. Johnson on the Nita 

 Crevasse on the Mississippi. It was stated that this crevasse was 

 the most extensive that had been opened for many years. Through 

 it an immense volume of water escaped into the lakes — a volume 

 not yet accurately measured, but probably equal to that of the 

 Missouri during flood, or that of the Delaware, Susquehanna, 

 Potomac and James rivers. The effect of this vast volume of 



