334: Scientific Intelligence. 



No. 90. The Cranberry Folio, North Carolina-Tennessee ; by 

 Arthur Keith. The mapping of the Cranberry district involves 

 the solution of some of the most difficult problems in Appalachian 

 geology. The region includes gneisses and granites of Archean 

 age, Algonkian ? schists, rhyolites and diabases, Cambrian sedi- 

 ments and basalt. The metamorphism has been extreme and the 

 fault structure is complicated and presents some unique features. 

 The text of this folio deserves especial mention as an illustration 

 of what can be done to make difficult geological structure intelli- 

 gible to the non-expert. - 



No. 91. Ilartville Folio, Wyoming; by W. S. Tangiek 

 Smith. The Hartville area shows a section of practically hori- 

 zontal sediments from Carboniferous to Recent. These strati- 

 fied beds are underlaid unconformably by Algonkian metamor- 

 phics, which in turn are cut by small masses and dikes of granite 

 and pegmatite. Iron and some copper are the economic products. 



2. The Correlation of Geological Faunas, A Contribution 

 to Dei'oniaji Paleontology ; by Henry Shalee Williams. — U. 

 IS. Geol. Surv., Bull. No. 210, 147 pp. Washington, 1903. 



Shifting of Faunas as a Problem of Stratigraphic Geology ; 

 by Henry Shaler Williams. (Bull. Geol. Soc. America, vol. 

 14, pp. 177-190, 16 pis. Rochester, April, 1903.) 



These two papers present the mature ideas of their author on 

 the subject of geological correlation. The studies were com- 

 menced in 1881 and have been carried on almost continuously 

 since. The chief area investigated has been the Devonian region 

 extending from Ohio across the southern counties of New York, 

 and the sections include all the Middle and Upper Devonian 

 strata from the top of the Onondaga limestone to the base of the 

 Olean conglomerate. 



The fauna of the typical Hamilton formation is called the 

 Troxndoleptus carinatus fauna. The fauna of the Black Shales 

 is the TAngula spatylata fauna. The third fauna, the Portage 

 Shales, is characterized as the Cardiola spjeeiosa fauna, while the 

 Chemung is the Spirifer disjunctus fauna. 



A great many of the frequency and range values of the species 

 occurring in these fossil faunas were determined, and from the 

 results it was possible to construct standard lists of the dominant 

 species with their relative percentages. These must always be 

 of great service in any faunal comparisons of the Devonian. The 

 methods employed are of course applicable to the Silurian or any 

 other formation, as well as to the Devonian, and similar com- 

 parative studies would result in standard lists for each. 



Considerable discussion is given regarding the shifting and 

 recurrence of faunas, and concrete examples are shown, together 

 with the methods of their correlation. The statistics of all this 

 work in its various aspects demonstrate the intrinsic value of 

 fossils for measuring and indicating time. No such positive 

 evidence is furnished by the sediments when considered on the 

 side of their lithological constitution, their structural form, or 

 their stratigraphical position. c. e. b. 



