170 Hints on the Iceberg Theory of Drift. 



mark to that effect upon it, that I never answered the letter ; and 

 if so I would gladly do something to atone for a seeming want 

 of courtesy. I must say, however, that my first ideas of the joint 

 action of ice and water in producing the phenomena of drift, were 

 derived from the views of Sir James Hall concerning diluvial 

 phenomena in Scotland ; for he introduces floating ice as one 

 of the agents ; but he gives no such distinct ideas of this agency 

 as Mr. Dobson and other recent advocates of the iceberg theo- 

 ry do. 



Vernon, Nov. 15, 1837. 

 Mr. Hitchcock, — 



Sir — I have read several good articles in the Biblical Reposi- 

 tory written by you on geological subjects, and I have now be- 

 fore me the one on " historical and geological deluges." I have 

 read what I have had an opportunity of seeing on these subjects, 

 and for a number of years 1 have been noticing some facts, which 

 I thought might throw some light on this interesting science ; 

 and as there is one physical fact that is common in this region 

 that does not appear to be noticed by you. I take the liberty to 

 address you on the subject. 



It is common to find bowlders of red sandstone in this neigh- 

 borhood, on and near the surface, as well as deep in the diluvial 

 masses of earth, that have been partially rounded by attrition, 

 and afterwards worn on one side rather flat, by a motion that has 

 kept the bowlder in one relative position, as a plane slides on a 

 board in the act of planing. Some of the bowlders are worn, 

 and scratched so plain, that there is no difficulty in pointing out 

 which side was forward, in the act of wearing, for it sometimes 

 happens that there are minerals of quartz and feldspar in them, 

 and if they happen to be in the part that has been worn, these 

 minerals being harder have protected some of the softer part of 

 the stone, so as to form a ridge from the mineral, as a wooden 

 pin would, driven into the plank of a stone drag, in that part 

 that is exposed to be worn by sliding on the ground. 



Some of these bowlders are so nearly round, that a powerful 

 current, sufficient to move them, would not cause them to slide 

 but to roll ; yet they have been made to slide so as to receive 

 distinct scratches, and the projecting minerals, I have no doubt, 

 have done some scratching on the rocks in place. Many of these 

 bowlders when dug out of the earth have a freshness of appear- 



