TERRACES. 



107 



and size on the two rivers affords a good illustration of the fact, that in general the larger the river the 

 higher the terraces. The character of the materials, too, illustrates another fact, viz., that they are coarser 

 on small and rapid streams, than on larger and more tranquil ones. Excepting the lowest, which are 



FIG. 49. 



150 



Fio. 50. 



Section from Vernon to Hinsdale, N. H., across Connecticut and Ashuelot Rivers. 



narrow, the terraces on the Ashuelot are all gravel, mixed with sand, and often the fragments are quite large ; 

 while on the Connecticut there are no pebbles of consequence, but sand underlaid by a thick bed of clay. 

 A third circumstance deserves notice. On the Ashuelot the terraces have a rapid slope towards its mouth, 

 corresponding to that of the river, which here falls so much as to afford a good site for manufactories ; 

 whereas on the Connecticut, the eye cannot perceive that the terraces are not strictly horizontal. Indeed, 

 they probably decline but little from Brattleboro to this place, and the two higher ones are nearly continu- 

 ous between the two places. The higher terrace along the Connecticut, not measured, is sandy and 

 irregular, and deserves more properly the name of a beach. 



By consulting Plate III, it will be seen that at South Vernon depot the rock approaches very near to 

 the river. As we go north, the terraces widen, following a range of hills running westward, and then north- 

 ward nearly at right angles to the first course, thus making the terraces to form a part of a basin within the 

 principal basin. It is because this range of hills is composed of quartz rock (see Geological Map) that it 

 is preserved, while the plain east of the quartz is underlaid by granitic gneiss, which decomposes more easily, 

 owing to the feldspar in its composition. 



Fig. 50 represents a section of the terraces on the west side of Connecticut river, in the north part of 

 Vernon, and differs from the one described in Fig. 49, on the opposite side of the river. The height of the 

 fourth terrace is greater ; but the spot is not a great 

 distance south of the gorge in the river at Brattleboro, 

 and hence we should expect a greater amount of ter- 

 race materials. The terraces now begin to narrow on 

 both sides, until they are entirely pinched out by the 

 clay slate approaching the river banks upon both sides, 

 yet they do not thin out at the same place ; those on 

 the west side are curtailed a mile or two before those < 



On the east Side. Section of Terraces on Conn. River on the west side, in N. Vernon. 



TERRACES IN THE BASIN FROM BRATTLEBORO TO BELLOWS PALLS. 



So narrow is the valley between Brattleboro and Westminster, that it deserves the name of a defile, 

 rather than a basin. And yet terraces are found nearly the whole distance, though usually quite narrow. 

 Opposite Brattleboro, on the east side of Connecticut River, West River Mountain rises very precipitously 

 to the height, above the river, of 1050 feet, and leaves no foothold for terraces. On the west sid'e of the 

 river, the hills rise more gradually. Within a distance of not over half a mile, two tributary streams empty 

 into the Connecticut : the most northerly called West River, of considerable size ; and the one at the south 

 end of the village, small, and called Whetstone Brook. Such streams debouching in such a spot, and at 

 right angles to the course of the Connecticut, are sure to produce numerous terraces. So numerous and 

 complicated are they that a separate map of them has been constructed, which though not entirely complete 

 is yet of great value in imparting instruction respecting river terraces. (See Plate VII, Fig. 2.) 



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jSaml 



107 



Sand 



-Leant 



