THE GRAVEL PIT. 21 



fastenings? And have you ever seen such mound cut through 

 for a highway or other purpose? If you have, you have wit- 

 nessed a semi-stratified order of deposition somewhat like that 

 in the Drift. Those who have thought on this resemblance 

 have reached the conclusion that the semi-stratified Drift must i 

 have been moved and laid down by some kind of torrential \ 

 action. 



But however this was, the origin of the bed of Bowlder 

 Clay must have been very different. Here is no sort of bed- 

 ding. The whole is in a state of uniform confusion. Evi- 

 dently, then, Nature employed two kinds of action successively 

 in transporting and dispersing the Drift. In the semi-stratified 

 Drifts water in tumultuous movement may have been the 

 chief agent. In the Bowlder Drift water was not the chief 

 agent, since here is none of the assortment and stratification 

 due to water, and here also are rock-masses moved scores or 

 hundreds of miles, and these results are not ascribable to water. 



Let us take another glance over the general distribution of 

 the Drift. We have seen the bowlders increasing in bulk and 

 abundance northward. We have seen the whole Drift forma- 

 tion terminating southward on about the parallel of Cincinnati. 

 We find incoherent surface deposits in Kentucky and southward ; 

 but they contain no bowlders ; and they have mostly resulted 

 from the disintegration and decay of the bed-rocks in place. 

 The Drift, then, is a northern phenomenon. 



If we notice more carefully the detailed distribution of 

 bowlders, we find that, while they have generally moved 

 southward, there has also been a radial distribution from high 

 mountains. In New Hampshire the bowlders move east and 

 west from the White Mountains, as well as south. In Switzer- 

 land, the Pierre a bot and thousands of other bowlders moved 

 north-westward from the Mont Blanc range though on the 

 opposide sides of Mont Blanc the movement was in the op- 

 posite direction. In the Rocky Mountains and the Sierra 

 Nevada, the movement of the bowlders was east and west 

 from the mountain axis. So, too, the southward distribution 

 of bowlders was greatest along mountain elevations. 



