Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/601

GIBEON,a town famous in Old Testamenthistory,known under the name of El Jib, situated 5 miles north-west of Jerusalem. It is now a small village standing on an isolated hill above a flat corn valley. The famous spring (2 Sam. ii. 13) comes out from under a cliff on the south-east side of the hill, and the water runs to a reservoir lower down. The sides of the hill are recky, and remarkable for the regular stratification of the limestone, which gives the hill at a distance the appearance of being stepped. Scattered olive grm‘es surround the place. The name is derived from the Hebrew root yabak, signifying “ prominence,” and there are throughout Palestine many ancient sites situate on rocky . knolls which receive names (e._r/., Gibeah, Geba, Gabe, Gaba—nearly all represented by the present J eba) deriVed from this same root.

GIBRALTAR, a British fortress and town in the south of Spain, occupying a grand peninsular headland, which stretches almost due south in a line with the eastern coast of the province of Andalusia, separating the Bay of Algeci- rrs from the open sea of the Mediterranean, and commanding the strait by which the Mediterranean communicates with the Atlantic. Its latitude is 36° 6' N. and its longitude 5° 20' 5;)" W. The “ rock,” as the promontory ls familiarly called, is about miles in length, with a varying breadth of from 2 to G furlongs. Rising abruptly from the low san-ly isthmus which connects it with the mainland to a height of 12.00 feet, the main ridge continues south for about miles, being separated by two transverse depres- sions, known respectively as the Northern and Southern Quebrada, into three pretty distinct summits—the Wolf’s Crag or North Front, the Middle Hill or Signal Station (1235 feet high), and the Pan do Azucar or Sugar Loaf Hill, dominated by O‘Hara’s tower (1108 feet). This last surn- rnit descends somewhat abruptly on the south to the Wind- mill Plateau, an almost level area about half a mile in length by a quarter in breadth, which, from a height of 400 feet above the sea, slopes south till it is only 300 feet above the sea, and then in its turn sinks abruptly for about "200 feet to the Europa Plateau, which, also sloping seaward, terminates in a cliff about 50 feet high. Towards the east 01' Mediterranean side the promontory presents as precipi— tous and inaccessible a front as towards the north, but towards the west the ascent is comparatively gradual though interruptel by longitudinal cliffs and ravines, and a corr- siderable space of fairly level ground at the foot affords a site for the town.

The basement rock of Gibraltar is for the most part a grayish white or pale grey limestone, of compact and some- times crystalline texture, arranged in beds, but in some places apparently amorphous. Above the limestone is a series of dark grey lsh blue shales with interealated beds and bands of grit, sandstone, and limestone; and distributed here and there about the promontory are various limestone breccias, bone-breecias, and calcareous sandstones, as well as loose sand and debris. It is evident that the whole promontory has had an eventfrrl geological history in corn- paratiVely recent periods. The limestone and the shales are both of Lower Jurassic age, brrt the rest of the form.- tions are of much more ancient date. According to the researches of Professors Ramsay and Geikie (“ Geology of Gibraltar,” in the Quarterly Journal of (Ire Cedar/foal .S'ociety, London, 1878),the oldest superficial accumulation is the unfossiliferous limestone breccia of Bucna Vista, which rnrrst have been formed under somewhat severer climatic conditions than the present, and when the rock had a wider area of low ground at its base. This period was probably followed by one with a genial climate, during which the promontory, if indeed it was not rather an isthmus between Europe and Africa, was clothed with vegetation and inhabited by a rich mammalian fauna, whose remains are still found in the Genista caves. Next there came a subsidence of a large proportion of the rock to the extent of 700 feet below the present level, the consequent erOsion of ledges and platforms, and the formation of the calcareous sandstones which have incorporated. shells of recent Mediterranean species. The process of depression was apparently interrupted by pauses. On its re-elcvatiou, the land was again of greater extent than now,- Africa and Europe were perhaps reunited, and the climate was probably genial. By a new depression the rock was brought into its present geo- graphical relations.

Chart of Gibraltar.

Like most masses of limestone formation, the promontory

of Gibraltar is honeycomde with caverns and subterrane- ous passages, and the Genista cave, already incidentally mentioned, is only one of the many to which it owes the title of the Hill of Caves. A special interest attaches to some of them for the palaeontological and archaeological remains which they yielded to the explorations of Captain Brome between 1863 and 186g. St Michael’s Cave, which is the most frequently visited by strangers, has its entrance about 1100 feet above the sea on the western face of the rock in the line of the Southern Quebrada. A rapid slope of earth gives admission to a hall 200 feet long by 70 feet high, the roof of which appears as if it were supported by massive stalactite pillars ; and from this hall access is obtained to a series of four similar caves connected with each other by tortuous passages, the last cave being situated about 300 feet below the surface, and about 400 feet of travelling distance south by west from the entrance. The first of the four was called Victoria cave by its dis- coverer Captain Brome, and the three others, being more

closely associated, received the common name of Leonora’s