Geological Society. 297 



and of the forms it assumes during its accumulation. He first con- 

 siders the causes of disintegration, independent of the immediate 

 action of running water j among which he principally enumerates 

 earthquakes, landslips, the various effect of oxidation, and the ex- 

 pansive powers of frost. He then describes the distribution of the 

 comminuted materials by running water, the manner in which they 

 become piled into obtuse cones in passing from lateral to principal 

 valleys, and the various causes modifying the erosive power of rivers. 

 From these subjects he proceeds to the forms assumed by alluvial 

 silt when carried down into standing water, the manner in which 

 lakes become gradually filled up, and the inclination of the stratified 

 masses resulting from the operation. Lastly, he describes the effects 

 produced at the junction of two streams, the depositions on the inter- 

 mediate stagnant points, and the forms of alluvial masses, whether 

 in rivers or lakes, produced by this compound action j and, from the 

 observation of these forms, he draws some practical conclusions re- 

 specting the probable accumulations at the bottom of the sea by the 

 opposition or the union of currents, whether flowing at the same or 

 at different levels. 



Questions of this kind are of most obvious importance j but they 

 admit of no illustration except by details ill fitted for the nature of 

 this address. I may however, before I finally quit this subject, remind 

 you of two opposite facts recorded in papers very lately read in this 

 Society, especially as they strengthen an opinion advanced at our 

 last anniversary that the river drainage of every physical region 

 is a complex result, always modified by local conditions, and often 

 depending upon the action of many successive causes. I have already 

 shown that in a part of Cumberland and Westmorland the valleys 

 are excavated upon the lines of ancient breaks or fissures. On the 

 contrary, in the neighbouring carboniferous chain of Yorkshire, the 

 faults and dislocations hardly ever range in the directions of the 

 valleys, and do not seem to have produced any sensible effect upon 

 the directions of the erosive currents. 



Again, the valleys of the carboniferous chain are of great depth, 

 and the strata on their opposite sides are generally horizontal and at 

 the same level j yet within these valleys we have in every river and 

 every tributary torrent, proofs, in my opinion the most unequivocal, 

 that the channels where the waters now flow have only existed during 

 a very recent period. 



I mention these facts for the purpose of urging upon you the 

 important truths, that geology has little to do with the combinations 

 of simple elements, and that we are in most cases called upon 

 sternly to reject such conclusions as are founded only upon particular 

 phenomena. 



Such, Gentlemen, are the subjects which have come before us 

 during the past year. They are neither small in number nor unim- 

 portant in their objects ; and whatever may be their other merits, 

 they at least prove that our body has manifested the activity of 

 healthy life. As we advance on our way, we gain strength at 



N. S. Vol. 9. No. 52. April 1831. 2 Q every 



