SCIENTIFIC SURVEY. 



393 



It is commonly the case that the junction of streams gives rise to 

 the formation of a greater number of terraces, than will be found 

 away from the confluence. But the elevation of the highest one 

 is no more than it is elsewhere along the valley. It is just so 

 here. Fig. 49 is a section of the terraces of the Kennebec, cross- 

 ing the valley just above the mouth of Dead river. The altitudes 



Fig. 49. 



A. 

 B. 



Kennebec river. 



Meadow, west side, 20 feet above 

 the river. 



C. Second terrace, 35 feet do. 



D. Third terrace, 40 feet do. 



E. Fourth terrace, 05 feet do. 



F. Fifth terrace, 70 feet do. 



Section at the Forks. 



G. Sixth terrace, 80 feet above the river. 



H. H. Solid roclss. 



K. First terrace on the east side, 15 



feet do. 

 L. Second terrace, 40 feet do. 

 M. Third terrace, 58 feet do. 

 JV. Fourth terrace, 70 feet do. 



were taken with an Aneroid Barometer, and arc laid off upon a 

 scale. Only the outline of the surface is given. We have not 

 attempted to show the order of superposition of the terraces in 

 relation to one another, but only of the whole to the solid rocks 

 beneath. The highest terraces upon both sides of the river in this 

 case appear to have the same altitude. This is not commonly the 

 case. The lower terraces are loamy, and the higher ones are com- 

 posed of fine and coarse gravel. 



A better illustration of the most common relations of terraces is 

 given in Fig. 50, measured at J. Carney's hotel in Moscow. The 

 materials are very coarse, the most so upon the east side, but the 

 forms of the terraces are perfect. The materials of E and F are 

 as coarse as common unmodified drift. Two very fundamental 

 facts are illustrated by this section, which must be taken into ac- 

 count in the formation of all oar theories respecting their origin ; 

 first, the heights of the highest terraces on the opposide sides of 

 the valley do not correspond ; nor, secondly, do the heights of any 

 of the intermediate terraces agree. Our theory of their origin has 

 been given in our Preliminary Report. 

 50 



