REVIEWS 121 



progressively displaced from late Tertiary to the present time, and 

 maturely carved by contemporaneous erosion. The evidence for this 

 conclusion is not structural, but physiographic. The base line of the 

 ranges is of gentle curvature, unrelated to the mountain structure. 

 The ravines by which the ranges are often dissected are narrow and 

 steep-walled to their very mouths. The spurs between the ravines are 

 often truncated systematically in a triangular facet at the mountain 

 base. All these features are necessary results of progressive faulting and 

 contemporary erosion, while they are not explainable on the theory 

 that the ranges are residuals of much larger masses, unrelated to 

 faulting. 



The Blue Ridge in Southern Virginia and North Caroli?ia. By 

 W. M. Davis. 



A RECENT visit to southern Virginia and North Carolina brought 

 clearly to my attention what many students of that region must know 

 already, but what is certainly unknown to geographers iji general, 

 namely, that the Blue Ridge is there not a ridge in any proper sense 

 of the word, but a southeast facing escarpment. The escarpment is 

 not due to any persistent rock structure, but results from the reduction 

 of the land surface to a relatively low level by the headwaters of the 

 short Atlantic rivers, whose drainage area therefore underlies that of 

 the larger west-fiowing rivers of the Mississippi system. The escarp- 

 ment occurs where the Atlantic streams are undercutting the uplands 

 of the Mississippi system. Residual mountains rise over the rolling 

 uplands of the Atlantic rivers and over the rolling highlands of the 

 Mississippi river : Kings and Pilot mountains are examples of the 

 first, and Mount Mitchell and Roan mountain of the second. Grand- 

 father mountain stands on the escarpment. 



The Protection of Terraces in the Upper Co7mecticiit Valley. By 

 C. H. Hitchcock. 

 The conclusions derived after many years of study relative to the 

 origin of the Connecticut river terraces north of Massachusetts are as 

 follows: (i) The higher terraces are part of a flood-plain deposited 

 by the waters derived from the melting of the ice-sheet. (2) A differ- 

 ential depression of level amounting to about one and one-fourth feet 

 to the mile in proceeding northerly greatly diminished the velocity of 

 the current, so that the material is much finer than it would have been 



