2J28 . The Rock of Gibraltar. 



strata, by which they were changed froui a horizontal into the 

 perpendicular situation ? 



^.^ Many may imagine that an answer is easily to be found to 

 J^ese questions. But I would rather at once confess, that this 

 ■problem appears )to Wjto belong Jtp jthj?, innumerable geological 

 mysteries, the proper time for the explanation of which has not 

 yet arrived. Supposing that it be undetermined in what way 

 the rock of Gibraltar obtained its present remarkable shape, still 

 we cannot be mistaken in saying, that the mass of the rock acted 

 as a powerful obstacle during the resistance which the southern 

 promontory of Spain made to the waters which attempted to 

 rush across or through it. The almost perpendicular strata of 

 flinty slate of the basis, and of the compact limestone of the 

 principal mass, would form with their whole surface a barrier at 

 right angles to the rush of water, and thus a stronger barrier 

 would be formed than by the soft sandstone strata of the neigh- 

 bouring districts. We have existing proofs upon the faces of 

 the rock, which cannot be mistaken, of the powerful workings of 

 the sea, and the influence which it has had in shaping the rock 

 all around. And we can see that the heaving up of the strata, 

 or their overthrow, in no way belonged to the period of the con- 

 vulsions by which the union of the Atlantic and Mediterranean 

 seas was effected. And in unison with the above facts, there 

 are deposits at the southern promontory, which shew the various 

 heights of the tides at periods before the bursting through of 

 the waters. The celebrated breccia containing bones, (knochen- 

 brekcie *) which fills up the crevices of the rock, and which first 

 drew the attention of naturalists to the rock of Gibraltar, occurs 

 likewise in many other parts of the Mediterranean. And this 

 circumstance is a proof that the Rock of Gibraltar was particu- 

 larly affected by the same revolutions which occasioned a re-for- 

 mation of the coasts of the Mediterranean Sea. 



The different sides of the narrow rock vary in form. On the 

 north and east side, the rock is in general so precipitous as to be 

 almost perpendicular ; while at particular places there are for- 

 midable overhanging masses. Upon the west side, on the con- 



• Vid. J. Frill, Blumenbachii Specimen Archseologije Telluris. 1803, 

 § 4. p. 0. 



