GLACIAL EROSION AXD TRAXSPORTATIOX. 243 



variegated pebbles of red jasper and of darker quartzites are 

 a striking feature in the rocks of that northern region. The 

 bowlders of this material found in the vicinity must have 

 been transported nearly 600 miles. Several bowlders of this 

 description were found in Boone county, Ky., a number of 

 miles south of the Ohio Eiver and between 500 and 600 

 feet above it. Bowlders of this jasper conglomerate are very 

 abundant in Michigan, are not infrequent in northern Ohio, 

 and occur in various localities in southern Indiana — one 

 beiug observed near Nashville, Brown county, Ind., near 

 the highest land in the State (about 1,100 feet). Granitic 

 and hornblendic bowlders are very abundant, also, as far 

 south as Carbondale, Jackson county, 111., below latitude 38°. 

 The surface rocks are here distinctly striated, and the trans- 

 portation must have been independent of any conceivable cur- 

 rent of water. The distance from this point to the parent 

 ledges to the north can not be less than 600 miles. 



All over northern Missouri, the whole of Iowa, and east- 

 ern Dakota bowlders of large size are of frequent occurrence. 

 In some places they completely cover the ground, especially 

 in the lines of the great moraines. Even west of the Mis- 

 souri, for thirty miles beyond Fort Yates, granitic bowlders 

 are so abundant as to be prominent features in the landscape. 

 Farther north in the same Territory and in Montana they are 

 reported as sometimes so thick that a person can walk for 

 long distances upon them without touching the ground. 



As has been already remarked, the glacial movement was 

 everywhere at right angles to the glacial boundary. We 

 should expect, therefore, to find that the bowlders along the 

 western border of the glaciated area beyond the Missouri 

 River had been transported from the northeast, and such is 

 undoubtedly the fact. In the recent excursion (in 1888) 

 through northern Nebraska and central Dakota, already re- 

 ferred to,* I had abundant occasion to see evidences of this 

 transportation. On the hills in Nebraska, from 500 to 600 



* See above, p. 174. 



