480 [Dec. 4, 



The following communication Avas read : — 



On the Geology of Gibraltar. By Jajmes Smith, Esq. of 

 Jordan Hill, F.G.S. 



In the absence of the author of this paper from England it has 

 been considered advisable not to publish more at present than a 

 mere announcement of the nature of the conclusions arrived at. 

 After stating briefly the appearance and character of the funda- 

 mental rock at Gibraltar (which is of the oolitic period), the 

 author mentions indications of recent marine action, extending up 

 to the very summit of the mountain, and proceeds to describe his 

 reason for concluding that great and repeated elevations have taken 

 place in the district in comparatively modern periods, three being 

 more especially remarkable, since each one of these has elevated 

 the strata through an angle of about 20°. Several interesting 

 phaenomena of the tertiary period are alluded to as affording 

 evidence in favour of this view. The author concludes by direct- 

 ing attention to some superficial deposits of .sand, covering the 

 flanks of the mountain, and to the bone breccia, some parts of 

 which he considers to be of great age. ' i 



December 4, 1844. 



Henry Coles, Esq., of Cheltenham, Dr. Travers Cox, Pro- 

 fessor Edward Forbes, and I. K. Brunei, Esq., were elected Fel- 

 lows of this Society. 



The following communications were read : — 

 1. Remarks on the Geology o/" British Guiana. By Sir Robert 



SCHOMBURGK, Ph. D. &C. 



The district alluded to by the author in this paper extends along 

 the shore of the Atlantic from the mouth of the Amazons river 

 to the embouchure of the Orinoco, its greatest length (between 

 Cape North and the confluence of the Rio Xie with the Rio 

 Negro) being about 1090 geographical miles, and its breadth 

 (from the mouth of the Orinoco to the confluence of the Rio 

 Negro with the Amazons) 710 miles. Throughout this tract no 

 organic remains have yet been discovered, the whole being occu- 

 pied by primitive rocks. 



The banks and low lands neai* the chief rivers of Guiana are 

 described as consisting at the surface of a bluish clay, impregnated 

 with salt and mixed with decayed vegetable matter, forming a 

 very productive soil. The delta of the Orinoco, and the em- 

 bouchure of the Essequibo, present the same appearance. 



The blue clay just described is usually succeeded by other clays 

 of variegated colour, and these again by sands, composed of trans- 

 parent white quartz. Water has been frequently obtained by 



