GLACIO-AQUEOUS ACTION IN NORTH AMERICA. 165 



haps make some advance in theory. This subject is one which 

 must necessarily be last in the order of geological study, because 

 the geologist must be thoroughly acquainted with the subjacent 

 rocks, before he can decide upon the origin and dispersion of that 

 deposit, which is made up of the spoils of all the formations be- 

 neath it. In the present paper, I propose to describe the pheno- 

 mena of our drift, especially as they have fallen under my own 

 observation, and then inquire how far they may be explained by 

 any legitimate theory. 



Let me however anticipate so much as to express the convic- 

 tion, that nearly all geologists would agi-ee in the principle, that 

 the phenomena of drift are the result of the joint and alternate 

 action of ice and water. And I regard this as the greatest ad- 

 vance which has been made of late on this subject. I use the 

 term Glacio- Aqueous to express this joint and alternate action, 

 not because the term suits me, or because I expect others will 

 adopt it, but because I cannot devise a better. The proof of such 

 an action I shall present as I proceed. 



The phenomena of drift will be arranged in this paper under 

 the following heads : 



1. Transported Bowlders. 



2. Smoothed, pohshed, and striated Rocks. 



3. Embossed Rocks. {Roches moutonnees.) 



4. Valleys of Erosion. 



5. Moraines. 



6. Detritus of Moraines. 



7. Deposits of Clay and Sand. 



8. Contortions of the Stratified Deposits. 



9. Terraced Valleys. 



10. Fractured Rocks. 



11. Organic Remains. 



1. Transported Bowlders. 

 The character of our bowlders shows them to correspond very 

 exactly with those so accurately described in the northern parts 

 of Europe. They are usually more or less rounded by attri- 

 tion, but frequently merely by the scaling off of then* angular 

 parts by disintegration. A more important fact in respect to 



