306 Scientific Intelligence. 



and bleak, were occupied by large forests. (Author's abstract.) 

 Mr. Reid afterwards read before the society a more detailed 

 account of the gravels which are exposed in thick deposits stand- 

 ing as abrupt bluffs on the sides of the bays beyond the present 

 position of the glacier front. 



In the paper by Prof. Wm. P. Blake upon " Dislocation in the 

 strata of the Lead and Zinc region of Wisconsin and their rela- 

 tions to the Mineral deposits, with some observations upon the 

 origin of the ores," attention was directed to the observations of 

 Percival in that field and their correctness as regards the faulting 

 and also to a direct relation of the faulted areas to the mineral 

 deposits as shown by the author's examination in the Shullsburg 

 region. Reference was made to the recent paper by Prof. 

 Jenney upon faults in the lead and zinc regions of Wisconsin and 

 Missouri in further confirmation, but the author rejects the views 

 of both Percival and Jenney in regard to the upward flow of 

 mineral solutions through the faults, and adopts substantially the 

 views of Prof. Whitney and of Prof. Chamberlin upon the original 

 deposition of the sulphides from sea-water in the mass of the 

 rocks and their subsequent concentration in the fissures and 

 crevices by a downward flow of the solutions due to oxidation; 

 but he directs attention however to the probable influence of the 

 dislocations upon the localization of the deposits ; first, by the 

 possible direct outflow of freshwater, or by gases acting as pre- 

 cipitants ; and second, by the destruction of organisms and the 

 accumulation of their remains near the faults. He also directed 

 attention to the petroleum shale, a thin layer, known as the " oil- 

 rock" which is generally the floor or bed-rock of the deposits of 

 blende, and upon which this ore usually spreads out and ends. 

 This petroleum, or the gases arising from it, appear to have had 

 more influence in determining the reprecipitation of the sulphides 

 than has hitherto been recognized. The fact that the lead and 

 zinc region is coincident in area with the " driftless area " is re- 

 garded as good evidence of the source of the metallic solutions 

 in the mass of the rocks which. have decayed by oxidation and 

 long exposure to the elements and have supplied metallic solu- 

 tions, which have been reprecipitated at lower levels. In conclu- 

 sion, attention was directed to the world-wide distribution of the 

 ores of lead and zinc in the older limestones and dolomites as 

 evidence of peculiar chemical conditions favoring the precipitation 

 of the ores of these metals from sea-water. (Author's abstract.) 



The winter meeting of the Society will be held in Boston, 

 Mass., beginning December 27, 1893, at the rooms of the Boston 

 Society of Natural History. Detailed information regarding the 

 meeting will be sent by the Secretary in due time. h. s. w. 



2. Geological Congress at Chicago. — At the World's Congress 

 on Geology held in the Memorial Art Palace, Chicago, August 

 24th, 25th, and 26th, the following papers were read and discus- 

 sions were held. 



On Thursday, August 24th : 



