Topographical Features of the New Haven region. 



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railroads (see the course of these raUroads between INIill River and the 

 Qninnipiac on tlie map). The whole height of the alluvium above mean 

 tide is in this region from 42 to 45 feet. The cnt through it for the rail- 

 roads extends nearly southwest and northeast, and is about two-thirds 

 of a mile, or 1200 yards, long. After the first 700 yards, the railroads 

 pass under a bridge, and just beyond, the separate cut for the Air- 

 Line railroad commences. The depth of the section is about 16 feet 

 at its Mill River end, 20 at the bridge, and 26 toward the upper or 

 Qninnipiac end. A number of interesting facts are to be observed in 

 the sections : 



a. The diminution in the proportion of pebbles on passing east from 

 the ]Mill River valley is well seen. Along the Air-Line road they con- 

 stitute hardly a fifteenth of the whole mass, although in an occasional 

 small layer they are of large size, even like cobble stones. 



Toward the more northern or Qninnipiac end of the cut, the layers 

 are not only less pebbly but the lower part of the section contains 

 two to four irregular layers of exceedingly fine clayey sand (M, fig, 2). 

 The material adheres rather firmly, holds water well, and is so damp 

 at all times that the exposed surface has in part become green from a 

 covering of moss. The clayey layers are separated by others of sand, 

 and an occasional one of pebbles. 



1. 



h. The alluvium is iu nearly horizontal layers, just as it was origi- 

 nally laid down. But these layers are quite irregular, often of small 

 lateral extent, and where composed of sand are very commonly made 

 up of wave-like parts, from two to many yards long, as in the annexed 

 figure — which represents a part of the surface six feet in height, about 

 half way from top to bottom in the Air-line railroad cut. 



c. A marked variation from horizontality occurs at the northern or 

 Quinnipiac end of the cut, where the layers, as shown very distinctly 

 in the firmer beds of clayey sand (fig. 2), dip downward four feet in a 

 length of 30 feet, or from ^\ to ?<\ feet above the railroad. This dip 

 is toward the Quhmipiac river, or toward the old harbor, and may 

 have some relation to the orioinal bottom of the basin. 



