PROCEEDINGS 



OF 



THE GEOLOGICAL SOCIETY OF LONDON. 



1830-1831. No. 18. 



Nov. 3. — In consequence of the Resolutions passed at the general 

 meeting held on the 18th of last June, changing the evenings of 

 ordinary meeting from the first and third Fridays in each month, 

 from November to June, inclusive, to the alternate Wednesdays, 

 the Society assembled on this evening for the session. 



The Rev. Thomas Boyles Murray, M. A. of Hart-street, Crutched 

 Friars ; James Edward Winterbottom, Esq. M.A. of Southampton- 

 buildings ; William Taylor, Esq. of Canonbury-square ; Charles 

 Shaw Lefevre, Esq. of Whitehall-place ; Rev. Dr. Arnold, head- 

 master of Rugby School ; Henry Ellis, Esq. of Wei beck street ; the 

 Right Hon. the Earl of Selkirk; and Dr. Bayne of Trinity College 

 Cambridge ; — were elected Fellows of this Society. 



The reading of a paper entitled " Remarks on the Formation of 

 Alluvial Deposits," by the Rev. James Yates, M.A. F.G.S., F.L.S., 

 was begun. 



Nov. 17 The Rev. William Kirby, M.A. ; Prideaux John Selby, 



Esq. of Twizell-house, near Belford, Northumberland ; and James 

 Dickson, Esq. of Kidbrooke, Blackheath ; were elected Fellows of 

 this Society. 



The reading of the paper on the Formation of Alluvial Depo- 

 sits, by the Rev. James Yates, begun at the last meeting, was con- 

 cluded. 



After adverting to the importance of this branch of Geology to- 

 wards the successful study of all the more ancient sedimentary depo- 

 sits, and to the explanation of the methods by which bare rocks are 

 converted into productive soils, the author proposes to describe 

 some of the processes which regulate the production of alluvium, 

 and the principal forms which it assumes. 



I. — He considers first those processes of disintegration, not de- 

 pendent upon the action of running water, by which materials 

 are supplied for the formation of alluvium. These are of two 

 kinds. 



1. — Earthquakes and landslips, by which large masses are detached 

 suddenly from the mountains, and fall occasionally with so great 

 an impetus as to extend across valleys. 



2. — Other processes, such as frost and oxidation, which are far 

 more important in their effects. The agents of this class always di- 

 vide rocks according to their natural structure of separation, so 

 that every fragment of the debris is bounded by the plane of its 

 cleavage. The fragments as they fall produce two principal forms j 



