aao Mtn'frahgkat Account of Gihraltaf, 



ral tend to the rhomboidal form, and arc from three to four inches long by two or three- 

 broad, and an inch and a half thick. They are not incrufted as the flints found in chalic,. 

 nor have they the appearance of having been worn by attrition. 



Upon different parts of the mountain, towards its bafe, are found large quantities of iand 

 compofed of different materials, and affuming various appearances as to colour. TJie largeft 

 bank of this arenaceous matter is upon the weftern fide of the mountain, and confifts of 

 fmall particles of cryftallized quartz, colourlefs, and perfedlly tranfparent per fe, but of an 

 ochreous colour in the mafs on account of a red argillaceous earth which adheres to them- 

 The fand of this bank is perfeiSlly loofe and uncombined : one half of it has been levelled 

 into an extenfive parade, its furfaee having been combined by the lime and rubbifh from the 

 ruins of the town. The fouthern extremity of the bank is ftill to be feen in its natural ftate,, 

 and forms the burying-ground of the garrifon. 



Upon the eaft fide of the mountain is found another of thefe banks, of confiderable extent,, 

 and, as I mentioned before, rifing from the Mediterranean in a rapid acclivity, and reach- 

 ing to one-third of its entire elevation. This bank is compofed of fmall particles of cryftal- 

 lized quartz, of teftaceous bodies rounded by attrition, and of a few minute particles of the 

 calcareous rock ; the whole has a whitifh grey colour. The rain-water which falls from 

 the bare mountain rock above the fand brings along with it calcareous matter, which is de- 

 pofited upon the bank, and combines its furfaee into a cruft, which in fome places is fo- 

 much indurated as to bear the preflure of the foot. 



In other parts of the mountain where this fand is furrounded by the calcareous rock, and 

 covered in and prote6ted from the a£lion of the air and corrofion of fea-falts, it is found in; 

 a perfedl indurated f}ate, combined by flaladlitical fpar, and forming a minute breccia. A 

 quarry of this arenaceous ftone has been opened upon the fouth-eaft quarter of the moun- 

 tain, and is made ufe of with great propriety to line the embrafures of fome of the new 

 works belonging to the garrifon. Its inaptitude to fly off in fplinters when ftruck by a 

 ball gives, in fuch fituations, additional fafety to the defenders of the place. 



The weftern fide of the mountain's bafe around Rofia Bay, and the New Mole, is a rock 

 compofed of an aggregate of fmall fragments of every foffil that has been here defcribed, with 

 the addition of two different fpecies of marble, that are probably adventitious, as their na- 

 tive beds have not been found in the mountain. The one of thofe is black, and the other of 

 an olive green colour.. The whole of this mixture produces a moft beautiful breccia, and is 

 firmly combined by a calcareous cement of a yellow verging towards an orange colour.. 

 It is fufceptible of a high polifh, except where fragments of the argillaceous llrata occur : 

 thefe can be eafily fmoothed down, but cannot be brought to a perfe£b polifh. The frag~ 

 ments in this breccia are angular, and none of them have the appearance of being water- worn. 



It only now remains for me to mention, what are generally called the foffil bones found 

 in the rock of Gibraltar. Thefe have been much talked of, and by fome looked upon as a., 

 phenomenon beyond the power of explanation. The general idea which exifts concerning 

 them is, that they are found in a petrified flate and inclofed in the folid calcareous rock ; but 

 thefe are miftakes which could only arife from inaccurate obfervation and falfe defcrip.^ 

 tion. 



In the perpendicular fiffures of the rock, and in fome of the caverns of the mountain (all 

 •f which afford evident proofs of their former communication with the furfaee), a calcarcour 



concretion 



