544 Professor Sc/nirtrz — Earth-movetnods, S. Africa. 



between the dolerite and the folded mountains is traversed by a large 

 number of quartz-veins filling in fissures, showing that the country 

 has been stretched. The explanation of this lies in the fact that 

 the thrust was conveyed by an infinite number of pulsations, small 

 earthquake waves, which, like the waves of the sea, battered upon 

 the shore represented b}' the old Madagascar ridge and caused the 

 pressure to accumulate by insensible gradation. At any rate the 

 dolerite dykes and the folded mountains stand in the relation of 

 cause and effect. The commencement of tlie movement was con- 

 temporary with the outbursts of volcanic energy in the Drakensberg 

 and also in tlie north in the volcanoes of the Kimberley series of 

 pipes. In the east the Karroo Lake had a deep hollow in which 

 sedimentation went on after it had stopped in the west, and the last 

 undoubted subaqueous sediments are llhaetic. The Cave Sandstone 

 and lied Beds which immediately underlie the lavas are more of the 

 nature of mud and ash poured out of the volcanoes ; the vertebrates, 

 however, found embedded in these latter are Jurassic — Dinosaurs and 

 primitive mammals. The main folding was finished before the 

 Cretaceous period, for the Neocomian beds are unaffected. 



The folded mountains reached to a very great height as compared 

 with the present sea-level, but then the land lay from 4,000 to 

 6,000 feet lower than it does now. The rocks involved in the folding 

 and structurally weak from the bending yielded enormous debris 

 heaps, Schutt-halden, whicli formed at their bases. There seems to 

 have gone on a sort of contemporaneous erosion and deposit of 

 a peculiar kind and on a gigantic scale, for the rivers and torrents 

 Avith their burden of gravel cut a level peneplane at 4,000 feet above 

 the present sea-level and then left behind on the plain a pile of gravel 

 which reaches 2,000 feet in thickness in places. This is the Euon 

 conglomerate, the lowest member of the TJitenhage (Neocomian) 

 Series. The mountains, then much lowered in altitude by the action 

 of torrents and swaddled at their bases with the Enon conglomerate, 

 no loiiger formed the collecting-points for the moisture-laden clouds, 

 and the country instead of being lashed with storms became tolerably 

 dry, or even desert, with, however, occasional lakes. In Central Asia 

 we have very similar conditions at the present day, and, to complete 

 the similarity, the Himalayas, Karakoram, and Kuen-Lun Mountains 

 shortly after their elevation yielded vast plains of boulders like the 

 Enon at no very remote date, just as our coastal mountains in South 

 Africa did in Lower Cretaceous times. The deposits of this dry stage 

 are represented by the Wood Eed, the middle series of the TJitenhage 

 formation ; the strata consist of marls, gypsiferous clays, blown sand, 

 and lake deposits. In the last a rich flora of Cycads, ferns, and 

 conifers has been found which are of Wealden age. On the margins 

 of the lakes Dinosaurs still continued to roam, but only a few have 

 been found ; one complete one unearthed at the Despatch Brickfields, 

 near TJitenhage, was converted into bricks before it could be saved ; 

 only a few pieces have yielded Dr. Broom sufficient material on which 

 to found his genus Algoasaurus. 



The land, however, was sinking, and at the close of the Wood Bed 

 period the sea invaded the land and flowed probably up to the central 



