Geological Society. 217 



along which these Plutonic appearances present themselves, is 

 flanked on either side by metalliferous deposits, but not of the same 

 kind, the copper ores being all found on one side of the range, the 

 lead ores on the other. An analogous case will be seen in Hum- 

 boldt's account of the country situate between the Oural and Altaic 

 chains. A fault or fissure is there traceable through not less than 

 16° of longitude, forming a crest or water-shed; the rocks are nearly 

 the same as those of Shropshire : they comprehend a granite (uncon- 

 nected with gneiss), clay-slate, grauwacke-slate, augitic porphyry, 

 and transition limestone, once compact but now granular. Ma- 

 lachite and red copper ore are found on one side of the ridge, argen- 

 tiferous galena on both. 



Such are the Plutonic phenomena, for an explanation of which 

 we rely chiefly on the assistance of chemistry; but there is another 

 train of phenomena which renders a close and intimate alliance be- 

 tween this science and our own no less desirable. The spontaneous 

 generation, shall I call it ? of agate, of chert, of hornstone, of flint, in 

 the midst of sedimentary calcareous deposits, apparently through 

 the instrumentality of animal or vegetable matter, in which little or 

 no silex is to be met with, is one of those mysterious operations of 

 nature which can nowhere be satisfactorily accounted for unless 

 in the laboratory. The coralline agates of Antigua, the entrochal 

 cherts of Derbyshire, the siliceous shells of Blackdown or Fontaine- 

 bleau, the chalcedonic alcyonia of Pewsey, pieces of fossil wood 

 either imbedded in strata or loosely scattered over sandy deserts, 

 the flinty casts of echini and other substances in the midst of our 

 chalk, all these suggest a course of experimental investigation which 

 we are entitled to hope, if undertaken in earnest, would not be un- 

 dertaken in vain. 



Gentlemen, I have great satisfaction in announcing to you, that 

 at the opening of the present Session of the Royal Society, one of 

 the Royal Medals was awarded to our Foreign Secretary as the au- 

 thor of the most important discoveries or series of investigations 

 sufficiently established or completed to the satisfaction of the Council 

 within the last five years, and for which no honorary reward had 

 been previously received. The Council of the Royal Society, pre- 

 mising that they decline to express any opinion on the controverted 

 positions contained in Mr. Ly ell's work, entitled " Principles of Geo- 

 logy," state the following as the grounds of their award. 



1. The comprehensive view which the author has taken of his 

 subject, and the philosophical spirit and dignity with which he has 

 treated it. 



2. The important service he has rendered to science by especially 

 directing the attention of geologists to effects produced by existing 

 causes. 



3. His admirable description of many tertiary deposits, several 

 of these descriptions being drawn from original observations. 



Lastly, The new mode of investigating tertiary deposits, which his 

 labours have greatly contributed to introduce; namely, that of de- 

 termining the relative proportions of extinct and still existing spe- 



Third Series. Vol. 7. No. 39. Sept. 1835. 2 F 



