Geological Society. 67 the St. Lawrence winding its way through a vast extent of level country, while in various parts extensive wooded islands were seen obstructing its course. On descending the south side of the moun-tain, which is closely wooded, the thermometer indicated 89° of Fahrenheit. The exertion caused by ascending and descending was severe ; and owing to the parched state of the ground, and the flaccid vegetables with which it was covered, walking was rendered nearly as difficult as over sea-weeds on a rocky shore." At this meeting the election of office-bearers for the ensuing year took place, when Dr. Douglas Maclagan was chosen President ; and Professor Graham, Drs. Lowe, Greville and Seller, Vice-Presidents. GEOLOGICAL SOCIETY. Nov. 20, 1844. — A paper was read " On the Geology of Gibraltar." By J. Smith, Esq., of Jordan Hill. The great rocky masses terminating Europe on the S.W. and Africa on the N.W., and cut through by the Straits of Gibraltar, con-sist of siliceous sandstones, associated with limestone, chert, shale and coal, all apparently of the oolitic formation. The Gibraltar limestone contains casts of Terebratula fimbria and T. concinna, species found in Britain in the lower oolite. The covering of the older rocks consists of soil, river alluvium, post-tertiary marine sands, and local patches of diluvium. Wherever the covering is removed, the surface of the rock beneath is seen to be water-worn. The rock of Gibraltar is 1470 feet high. The southern extremity is marked by a triple series of terraces and inland cliffs, formed by the sea at former levels. Its northern terminates in a perpendicular cliff. 7'he elevated part is divided into three distinct eminences, the effects of different local upheavals. The northern of these (the rock gun) does not appear to have undergone any derangement in its stratification since its first upheaval, although it must have been subjected to many elevations and depressions of level. Its older beds (those of the limestone) dip west at an angle of 20°, and those formed since the elevation are horizontal, remaining in their natural position. In this state the whole of the rock must have remained for a lengthened period, until a second upheaval broke it across, leaving the northern portion in its original position, but lifting the whole of the southern 20° more, so that its beds, which formerly dipped 20° west, now dip 40° ; and the fresh deposits, formerly horizontal, 20°. On these deposits, others, formed after the upheaval, rest unconformably. A third upheaval in the same direction, but still further to the south, lifted the rock there about 20° more, leaving the northern and middle hills in their former position, but inclining the southern 60°. Thus we have four distinct epochs ; of the deposits formed during each we have remains, and at Martin's Cave the whole may be seen in juxtaposition. Immediate-ly under O'Hara's tower, the highest peak, the inclination of the beds to the west is nearly 80°, and a short way to the south of it, they are vertical. Under this point there is, at the height of about F2
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