506 A. C. RAMSAY AND J. GEIKIE ON 



We append a list of the various papers relating to the geology of 

 the rock which are known to us. There may be accounts of the 

 peninsula by Spanish geologists, but these we have not seen ; and 

 perhaps other papers by English authors may have escaped our 

 notice. 



" Mineralogical Description of the Mountain of Gibraltar," by 

 Major Imrie. Edinb. Roy. Soe. Trans, vol. iv. (1798) p. 191. 



" Notice concerning the Tertiary Deposits in the South of Spain," 

 by James Smith, Esq. (of Jordan Hill). Quart. Journ. Geol. Soc. 

 vol. i. p. 235. 



" On the Geology of Gibraltar," by James Smith, Esq., of Jordan 

 Hill, E.G.S. Quart. Journ. Geol. Soc. vol. ii. p. 41. 



" On the Geology of Malaga and the southern part of Andalusia," 

 by Professor D. T. Ansted, M.A., F.R.S., E.G.S. Quart, Journ. 

 Geol. Soc. vol. xv. p. 585. 



" On the Evidences of Eecent Changes of Level in the Mediter- 

 ranean Coast-line," by George Maw, Esq., F.L.S., E.G.S., &c. Geol. 

 Magazine, vol. vii. p. 548. 



" On the Eossil Contents of the Genista Cave, Gibraltar," by G. 

 Busk, Esq., F.R.S., E.G.S., and the late Hugh Falconer, M.D., 

 V.P.R.S., Eor.Sec.G.S. Quart. Journ. Geol. Soc. vol. xxi. p. 364. 

 See also same paper, with additional notes, " Palaeontological 

 Memoirs and Notes of the late Hugh Falconer, A.M., M.D.," vol. ii. 

 p. 554. 



Mr. Busk has a paper " On the Caves of Gibraltar in which Human 

 Remains and Works of Art have been found " in the volume of the 

 Prehistoric Congress at Norwich in 1868 (1869). 



" Quaternary Fauna of Gibraltar," by George Busk, Esq., F.R.S., 

 Zool. Trans, vol. x. part 2, 1877. 



Physical Description. 



The Rock of Gibraltar, as every one knows, forms a well-marked 

 promontory that trends in a direction south by west into the Medi- 

 terranean. The extreme length of the Rock, measured from the 

 base of the cliff at the North Front to Europa Point, is only a little 

 over 2| miles, and the promontory tapers somewhat gradually away 

 from a breadth of 1550 yards between Gibraltar and Catalan Bay 

 to a width of 550 yards at Europa. The Rock shoots abruptly 

 upwards from the low flat ground at the North Front in a fine 

 mural precipice, the basal portion of which is partly concealed by a 

 sloping curtain of debris and breccia. This precipitous wall culmi- 

 nates in a height of 1349 feet at the Rock gun, from which point 

 the dividing ridge or backbone of the promontory extends south- 

 wards in a sharp jagged arete, the dominant points of which are 

 Middle Hill (1195 feet), Signal Station (1294 feet), heights above 

 Monkey's Alameda (1396 feet), and O'Hara's Tower (1370 feet). 

 At the latter the ridge is abruptly truncated, and succeeded to the 

 south by the well-marked plateaux of Windmill Hill and Europa. 

 From the Rock gun to O'Hara's Tower the dividing ridge presents 



