Geology and Mineralogy. 307 



0. A. Derby, of Brazil: The general geology of Brazil. 



Adolph Erxst, of Venezuela : The general geology of Venezuela. 



Henry Hicks, of England: Pre-Cambrian rocks of Wales. 



Henry M. Ami, Canada: The classification of the rock formations of Canada, 

 with special reference to the Paleozoic era. 



A. C. Lawson: The Cordilleran Mesozoic revolution. 



C. W. Hall : The Pre-Paleozoic floor in the iSTorthwestern States. 



George H. Williams : Distribution of Pre-Cambrian volcanic rocks along the 

 eastern border of the United States and Canada. 



After discussion of the above papers, the special discussion for 

 the day was upon the question, " Are there any natural geological 

 divisions of world-wide extent?" 



On Friday, August 25 : 



A. R. C. Selwyx, of Canada : Huronian versus Algonkian. 

 Alfred Harker, England: On the migration of material during the meta- 

 morphism of rock masses 



Warrex Upham: Wave-like progress of an Epeirogenic uplift. 



0. A. Derby, of Brazil : Eruptive phenomena of Brazil. 



W. J. McG-ee : Genetic classification of Geology. 



George F. Ktjnz: Precious stones and their geological occurrence. 



C. R. Van Hise : The extent and lapse of time represented by unconformities. 



Lester F. Ward : The Phylogeny of plants. 



0. Jaekel, of Germany : The Phylogeny of the classes of vertebrates. 



S. W. Willistox: Restoration of Clidastes (illustrated). 



After the reading of the papers, the question for the special 

 discussion of the day was, " What are the principles and criteria 

 to be observed in the restoration of ancient geographic outlines ? 



On Saturday, August 26 : 



James Geikie : Glacial succession in the British Isles and Northern Europe. 

 Hjalmar Lundbohm, of Sweden: Glacial succession in Sweden. 

 Robert Bell, of Canada: The succession of the Glacial deposits of Canada. 

 T. C. Chamberlin : Glacial succession in the United States. 

 Warren Upham: Pleistocene climatic changes. 



Fraxk Leverett: Evidences of the diversity of the older drift in northwestern 

 Illinois. 



The special discussion for the day was upon the question, 

 " What are the principles and criteria to be observed in the corre- 

 lation of Glacial formations in opposite hemispheres ? 



h. s. w. 



3. Geological Time. — Prof. C. T>. Walcott, in his address before 

 the Geological Section of the American Association on " Geological 

 Time as indicated by the Sedimentary Rocks of North America," 

 gave the following estimates of the length of time required for 

 the formation of the grander divisions of sedimentary rocks. 



For the Cenozoic, including Pleistocene, 2,900,000 years ; 

 the Mesozoic, 7,240,000 years; the Paleozoic, 17,500,000; the 

 Algonkian, 17,500,000; the Arch sean ? 



4. Annual Report, for 1892, on the Geological Survey of 

 Texas, under E. T. Du.mble. — The following parts of this fourth 

 Annual Report of the Texas Geological Survey have recently 

 been issued. 



(1) A preliminary report on the Vertebrate Paleontology of the 

 Llano Estacado by E. D. Cope. 88 pp. 8vo, with 23 plates. 



