232 Longwell — Structure of the Tr lassie 



bedding, the angularity and lack of assortment displayed 

 by the fragments, and the evident source of the material, 

 leaves no doubt that the coarse sediments were deposited 

 in the form of fans at the base of a steep scarp or slope 

 by small streams flowing westward. 



A number of these fans are recognized along the fault 

 between Branford and Durham. Perhaps the most con- 

 spicuous example is exposed in the bluff on the west side 

 of Lake Quonnipaug, several miles northeast of the area 

 represented in the map, fig. 1. At that locality the angu- 

 larity of the fragments making up the fan is truly remark- 

 able. Even in the Great Basin the writer has not seen 

 products of erosion which show as little evidence of trans- 

 portation except in talus deposits, and yet the material 

 at Lake Quonnipaug has the rude bedding characteristic 

 of coarse fans. We can only conclude that the sediments 

 now exposed at that place were deposited directly in 

 front of a cliff, and the fragments were supplied by very 

 local streams. 



The best example of a fan in the Saltonstall basin is 

 located about two miles from Branford in a direction 

 slightly east of north. (See fig. 1.) E. 0. Hovey 7 and 

 J. D. Dana 8 commented on the unusual character of the 

 conglomerate at this locality. Hovey refers to the area 

 occupied by the deposits as the "bowlder ridges/' and 

 he has described the essential features of the section as 

 follows : 



"The region containing the most interesting part of the con- 

 glomerate, i. e. the ridges, is about three-fourths of a mile long 

 from S. W. to N. E. and perhaps half a mile wide. There are 

 several of these ridges each of which is 300 to 400 yards long ; and 

 their general trend is N25°E. They are narrow, begin and end 

 abruptly, have almost precipitous sides, and rise about 125 feet 

 (aneroid measurement) above the brook and meadow bounding 

 their region on the east and south. The valleys between them 

 are narrow and from 40 to 60 feet deep 



' ' The rock of the ridges is exceedingly coarse. Weil rounded 

 bowlders a foot in diameter are very numerous, while others two, 

 three, and even four feet long are by no means rare. Much trap 



7 Hovey, E. O. : Observations on some of the trap ridges of the East 

 Haven-Branf ord region, with a map : This Journal, 3d ser., vol. XXXVIII, 

 pp. 361-383, Nov. 1889. 



8 Dana, J. D. : The Four Bocks, with walks and drives about New Haven, 

 p. 191, 1891. 



