992 



SCIENCE. 



[N. S. Vol. XII. No. 313. 



of an actual shore line during Oriskany 

 time. No Helderbergian deposits occur in 

 this western section of the State. The 

 transgression of the Oriskany here is in 

 conformity with similar evidence in other 

 regions, of its wide extent beyond the limits 

 of the preceding Helderbergian formation. 



A second paper by Dr. J. M. Clarke, 

 on ' The Fauna of the Arenaceous Lower 

 Devonian of Aroostook County, Maine,' 

 brought out the fact that a careful re-study 

 of this fauna indicates that its proposed 

 construction as a Silurian fauna correlating 

 with the Tilestones of Murchison's Silurian 

 section is not justified by the character and 

 affiliation of its species. With such New 

 York Oriskanj'^ species as Anoj)lia nucleata, 

 Cyrtina vavM, etc., it contains a number of 

 species identical with those of Lower De- 

 vonian faunas of Western Europe. The 

 faunas of the two localities of the Chapman 

 Plantation, Edmund's Hill and Presque 

 Isle Creek, have very little in common, but 

 both show a close alliance with the are- 

 naceous Lower Devonian faunas. 



A paper on ' The Great Chisos Rift along 

 the Canyons of the Rio Grande River,' by 

 Professor R. T. Hill, and embodying the 

 results of a trip by him through the lower 

 portion of this canyon late in 1899, was one 

 of unusual interest, as the region described 

 was entirely new to the scientific world and 

 one which proved to be varied and beautiful 

 in scenery, and rich in geologic and topo- 

 graphic problems. The paper was illus- 

 trated by a considerable number of lantern 

 slides prepared from photographs taken by 

 Professor Hill during his journey. 



In a short paper, ' Notes on the Geology 

 of Central South Carolina,' Dr. D. S. Martin 

 described the work about Columbia now 

 being carried on by himself and Dr. L. C. 

 Glenn, and the success of the latter in dis- 

 covering eocene and cretaceous beds sepa- 

 rating the ' Potomac ' and ' Lafayette ' de- 

 posits, which in many of the new railway 



cuts about Columbia are lithologicallj' in- 

 distinguishable. 



Dr. Alexis A. Julien read a paper on 

 ' The Genesis of the Pegmatite in North 

 Carolina,' in which he called attention to 

 the constant association of vein and of dike 

 phenomena, hitherto without satisfactory 

 explanation in the pegmatite occurrences 

 in the schists of that State and along the 

 Appalachian belt. The several genetic hy- 

 potheses were reviewed, based on intrusion 

 of fused magma, vein-infiltration, segrega- 

 tion and pneumatolytic introduction of ig- 

 neo-aqueous magma. But none of these ac- 

 counted for important facts observed, e. g., 

 vast pegmatite masses connected with al- 

 most capillary fissures, frequent distinct re- 

 lationship of the material of the pegmatite 

 and adjoining schists, and the almost uni- 

 versal banded structure and evidences of 

 mineral concentration within the pegma- 

 tite. In their place he proposed the hy- 

 pothesis of metasomatic aggregation, by 

 molecular rearrangement of the entire ma- 

 terial of portions of the schists in vicinity of 

 fissures, through the action of mineralizers ; 

 lateral segregation within the igneo-aqueous 

 magma or emulsion so formed, with produc- 

 tion of vein-structure, etc.; crushing and 

 even shearing, byorogenic movements, trans- 

 lation along the fissure-plane, partial obliter- 

 ation of vein-structure and development of 

 facies of a dike. On such an occurrence of 

 pegmatite, therefore, one looks upon the 

 birth of granite in loco, in at least one mode, 

 rather than upon an intrusion of foreign 

 material into cavities of discission or disso- 

 lution. 



' The Geological Features of the Meno- 

 minee Iron District of Michigan ' wei'e de- 

 scribed in a short paper by W. S. Bailey, 

 as occupj'ing an area of about 120 square 

 miles on the north side of the Menominee 

 river, from Waucedah westward to a short 

 distance beyond Iron Mountain. The ore- 

 producing rock constitutes a trough be- 



