OF GIBRALTAR. 17 



sand consists of grains of quartz, to which adheres 

 an argillaceous earth, strongly impregnated with 

 iron ; hence its peculiar red colour. It appears to 

 be of marine origin, and is distinctly stratified. 

 The sandbank near Catalan Bay is nearly five hun- 

 dred feet high, and is considered to be blown sand, 

 resting at an angle of fifty degrees ; under it is a 

 thinly stratified deposit of sand-stone. 



Many conjectures have been made with respect to 

 the geological history of this rock, but I believe that 

 it may be safely considered to belong to the Jura 

 limestone system ;* the rocks in the neighbourhood, 

 as has been already observed, consist of sand-stone 

 and limestone, with thin strata of coal. A coal 

 deposit is found within four miles of Gibraltar, but 

 not of sufficient thickness to make it desirable to 

 work the beds. I have seen similar deposits near 

 Malaga, under similar circumstances. 



Mr. Smith of Jordan Hill, well known to the 

 scientific world as a naturalist and geologist, resided 

 for several years at Gibraltar, and having made him- 

 self acquainted with every fissure and cliff of the 

 rock, recently laid before the Literary Society of 

 Gibraltar, a new view of the formation of the rock of 

 Gibraltar, which I believe forms the substance of 

 a paper lately read before the Geological Society 

 of London. In the former paper, Mr. Smith, after 

 describing minutely every feature impressed upon 



* The Gibraltar limestone contains casts of Terebratula 

 fimbria and T. concinna (Smith}. See Appendix. 



C 



