140 W. H. HOBBS — FORMER EXTENT OF THU NKWARK SYSTEM 



definite conclusion, though they seem to favor the generally accepted 



view.* 

 The following statement, however, is made in their report : 



" It is evident that the field now occupied by the Newark beds of the Eichmond 

 basin was at one time much more extensive than it is at present. Its extreme 

 limits cannot well be determined. As is well known, the eastern margin of the 

 field is bordered by several small detached areas, in which are preserved the lower 

 coal-bearing strata. . . . It is not improbable that small basins similar to the 

 Black Heath lie beneath the common mantle of residual deposits as far to the east 

 as the meridian of Richmond, or, say 12 miles from the ascertained exposures of 

 the Newark series. . ■ . . 



"The distribution of the remaining portions of the Newark beds in Virginia is 

 consistent with the hypothesis that the deposits once mantled that field over, the 

 several areas still existing owing their preservation to their inclusion in the troughs 

 arising from the dislocation of the basement. It is also reconcilable with the sup- 

 position that the beds were laid down in preexisting valleys, the lesser basins 

 grouped about the greater being peripheral remnants of the once more extended 

 areas." f 



Dr Woodworth, in a personal letter to the writer, says : 



" I am rather inclined to a broad terrane distribution of the Newark for the 

 upper and lower middle sections where I have seen them. I suspect the geography 

 was somewhat like that of the Great Basin, and that enormous denudation has 

 taken place." 



Explanation of general Acceptance of " Local Basin " Hypothesis 



To the writer it seems that the general adhesion to the " local basin " 

 hypothesis on the part of geologists who have studied the Newark sys- 

 tem, may have its explanation in the position from which the study has 

 been approached and the manner in which the investigations have been 

 conducted. The first continuous terrane hypothesis — that of Rogers for 

 the areas south of New York — was so unsatisfactory as to prejudice 

 more or less the later theories which involved a continuous terrane. 

 On the other hand, the early description of the Acadian area— the one 

 really isolated Newark area — as a separate basin, with deposits formed 

 in a bay swept by strong tidal currents, required little change from pres- 

 ent conditions in the bay of Fundy, and possessed a large measure of 

 probability. Le Conte and Newberry seem to have accepted the local 

 basin hypothesis and given color to their writings in harmony with this 

 view, so that the doctrine early acquired a considerable momentum 

 from the weight of authority behind it. Of no little importance also as 



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

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

 fOp. cit., pp. 413, 414. 



