8 TOPOGRAPHY 



lover of nature the pains he may take in going down 

 to this spot to see and admire the sports of the ele- 

 ments on this rock-girded coast. The hay of Gib- 

 raltar which bounds the promontory on the west, is 

 nearly eight and a half miles long ; its breadth is 

 upwards of five miles, and its circumference between 

 twenty and thirty miles. At spring tides the water 

 rises about four feet. I must refer the reader to other 

 works for an account of the currents in the Mediter- 

 ranean. Spix and Von Martius, in their " Travels in 

 Brazil," treat this subject with their usual ability. 



The rock of Gibraltar consists of secondary lime- 

 stone, calcareous spar, breccia, clay-shale, and sand- 

 stone. Hornstone is also occasionally seen in small 

 quantities. The limestone is distinctly stratified, the 

 stratification being more marked on the surface. 

 Its inclination varies considerably, at one point the 

 strata being almost perpendicular, and at another 

 nearly horizontal. The dip is generally from east 

 to west. The colour of this limestone varies from a 

 light yellowish ashy gray to a smoky gray. Its 

 structure is compact, and it is traversed by veins 

 of calcareous spar of a whitish colour ; sometimes it is 

 seen in a foliated, but more frequently in a crystallized 

 state. 



Caves of various size exist in this formation. 

 The largest, called St. Michael's Cave, is situated 

 about the middle of the rock, and nearly eleven 

 hundred feet above the level of the sea ; perhaps 

 there are few caves in similar formations equal to 

 this in picturesque effect, though there are many of 



