2 Remarks oil the Formation of Alluvial Depos'ites. 

 of animal and vegetable life ; and, from the first origin of or- 

 ganized beings, similar processes must have been necessary to 

 afford the means for their growth and propagation. We may 

 further remark, that the laws of alluvial action form an indis- 

 pensable and very prominent part of the science of Hydrogra- 

 phy, and that without due attention to them. Comparative 

 Geography must remain exceedingly imperfect. Even the most 

 recent maps of the ancient world, edited by Reichard, Cramer, 

 and the Society for diffusing Useful Knowledge, are so delineated 

 as to remove ancient sea-ports to a great distance from the sea, 

 and to include in the Continent what were formerly islands, so 

 that many alluvial tracts in these maps are only ancient, in as 

 much as ancient names are wi-itten upon them. 



The observations which I shall venture to offer to the So- 

 ciety, will relate to the four following branches of the sub- 

 ject :~ 



Istf The preliminary processes of disintegration, not imme- 

 diately dependent upon the action of running water, by which 

 materials are furnished for the formation of alluvium. 



^dly. The action of running water in distributing these ma- 

 terials over level or inclined surfaces. 



?>dly. The effects produced, when such materials are con- 

 veyed by running into standing water. 



^thly. The case of a stream of water, which meets a stream 

 flowing in another direction. 



My viev/s upon these subjects are founded upon observations 

 made both in this island and in various parts of the Continent, 

 but especially in Switzerland ana Savoy. 



!• — On the Preliminary Processes of Disintegration, not immediately 

 dependent upon the Action of Running Water, by which Materials 

 are furnished for the Formation of Alluvium. 



The question has often been debated, whether water, flowing 

 with the greatest possible velocity, or in the largest volume, is 

 sufficient by itself to erode the harder rocks, or to excavate in 

 them ravines and valleys. My own opportunities of observation 

 would lead me to answer this query in the negative. The un- 

 shaken solidity and durable forms of rocks and pebbles, which 



