530 



CENOZOIC TIME. 



ing lines of stones crossing valleys and hills without deviation from a 

 right line, are examples of a very general fact with regard to the Drift. 

 At the same time, the trains often follow the directions of the grander 

 slopes of the surface, and especially the courses of the larger valleys. 



A range of country on the west side of the Connecticut "Valley, near the borders of 

 the Triassic, has in Connecticut great numbers of trap bowlders — some 500 to 1,000 

 tons weight — which have been transported from the trap hills of the valley, in a direc- 

 tion 5° to 20° west of south, this being, in Connecticut, the direction of the Connecticut 

 Valley (though not of the river, see p. 404). The same general fact is illustrated in all 

 glacial regions. 



On the other hand, bowlders were sometimes carried up slopes, to a 

 height of a thousand feet or more. Thus, limestone bowlders from 

 Canaan, Conn., were carried southeastward, up to Goshen, 1,000 feet: 

 and fossiliferous bowlders from the region north of Mt. Katahdin were 

 left on that mountain, at a height of 4,385 feet above the sea, or more 

 than 3,000 feet above the low country to the north. 



II. Attendant Phenomena — Groovings or Scratches. 



1. Evidences of Abrasion. — Besides the transportation of stones 

 and earth, there was the abrasion of rocks, which left nearly the 

 whole rocky surface of the country, within Drift regions, scratched or 

 grooved and polished. The following figure (Fig. 940) represents a 

 slab of limestone, from western New York, thus scratched and planed 

 off. 



Fig. 940. 



Drift groovings, or scratches. 



In addition, the stones and large bowlders of the Drift are often 

 scored, like the rocks over which they travelled. 



The bare ledges have not often retained the scratches, unless they consisted of slate 

 or limestone, or some hard varieties of gneiss. But these, and even the softer rocks, 

 are generally found to be grooved or polished, wherever the soil has been recently 

 removed. 



