30 



.lOUKNAL OF THE 



Turning to the United States and selecting a few places 

 where the necessary horizontal homogeniety is found, we 

 have no trouble in pointing out examples. "The south 

 side of the island of Long Island is a plain of remarkable 

 evenness, descending with gentle inclination from the 

 moral nic ridge of the interior to the Atlantic Ocean. It is 

 crossed by a great number of small streams which have 

 excavated shallow valleys in the homogeneous modified 

 drift of the plain. Each of these little valleys is limited 

 on the west or right side by a bluff from ten to twenty feet 

 high, while its general slope on the left side merges imper- 

 ceptibly with the general plain. The stream in each case 

 follows closely the bluff at the right."* 



The peculiar to- 

 pography of the east- 

 ern portion of the 

 Carolinas, where the 

 necessary conditions 

 exist, has been point- 

 ed out by Tuomey 

 and by Kerr. Here 

 the streams have cut 

 through the Quater- 

 nary and Tertiary 

 formations, and well 

 into the Cretaceous, 

 and in every instance 

 they present the high 

 right bank, with the 

 ow sloping country 

 on the left; and, as 

 may be seen by the 

 sketch-map, the 

 tributaries of the 

 Roanoke, the Tar, 



Map of a 



PORTION Of 



HoRTH Car^olina 



Fig. III. 



(;. K. (Gilbert. Am. Joiir. Set. 3d xxvii. 431. 



