142 W. H. HOBBS FORMER EXTENT OF THE NEWARK SYSTEM 



England to Virginia * They are the reports by Emerson on the Massa- 

 chusetts portion of the Connecticut Valley area; by Davis on the Con- 

 necticut portion of the same area ; by Kiimmel on the New York-New 

 Jersey area; by Shaler and Woodworth on the Richmond area, and by 

 the writer on the Pomperaug Valley area. Keith's study of the Catoctin 

 belt had appeared in 1894. f These extended investigations make pos- 

 sible a review of the subject of Newark conditions of deposition and the 

 area over which they extended. 



Local Basin versus " Broad Terrane " Hypothesis 



11 local basin" hypothesis 



The observed phenomena which the " local basin " hypothesis has 

 been framed to explain, seem to be: (1) The present occurrence of the 

 terrane in circumscribed areas separated by other and generally older 

 horizons; (2) the nature of. the sediments, which indicate shallow and 

 brackish water deposition, and, (3) the occurrence of coarse arkose and 

 conglomerate, interpreted to indicate that powerful transporting agencies 

 were at work when these sediments were deposited. 



The new light thrown on the problem by recent studies, in the opinion 

 of the writer, furnishes the data for a more satisfactory explanation of 

 these phenomena on the basis of a continuous and broad area of depo- 

 sition, at least for all save the Acadian area. 



MARGINAL FAULTS FAVOR "BROAD TERRANE" HYPOTHESIS 



The most important single line of observations derived from the re- 

 cent studies and bearing upon the problem, is that which shows that all 

 the areas recently studied are largely surrounded by observed faults or 

 by probable faults, and that the Newark terrane is generally at a lower 

 level than the older rocks by which it is surrounded. This result was 

 foreseen by Russell in the trend of his own and other observations at 



* W. M. Davis : The Triassic formation of Connecticut. Eighteenth Ann. Rep. of U. S. Geolog- 

 ical Survey, pt. ii, 1898, pp. 1-192. 



B. K. Emerson : Geology of old Hampshire county, Massachusetts, comprising Franklin, 

 Hampshire, and Hampden counties. Monograph 29, U. S. Geological Survey, 1898, pp. 351-501. 



H. B. Kummel : The Newark system of Red Sandstone belt (in New Jersey). Ann. Rep. State 

 Geologist of New Jersey for 1897. Trenton, 1898, pp. 25-159. 



H. B. Kummel: The extension of the Newark system of rocks (in New York). Ann. Rep. 

 State Geologist of New Jersey for 1898. Trenton, 1899, pp. 43-57. 



N. S. Shaler and J. B. Woodworth : Geology of the Richmond basin, Virginia. Nineteenth 

 Ann. Rep. U. S. Geological Survey, pt. ii, 1899, pp. 385-519. 



W. H. Hobbs : The Newark system of the Pomperaug valley, Connecticut, with a report on fossil 

 wood by F. H. Knowlton. Twenty-first Ann. Rep. U. S. Geological Survey, pt. iii, 1901, pp. 1-162. 



t Arthur Keith : Geology of the Catoctin belt. Fourteenth Ann. Rep. U. S. Geological Survey, 

 pt. ii, 1894, pp. 345-385. 



