24 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [iSToV. 8, 



above the sea, I think no one who studies even the botany of the 

 Cape can have doubts that the flora, as a whole, is that of an insular 

 region, and points to a time when South Africa was an island oi", it 

 might be, an archipelago. 



However much the following paragraph may apply to some parts 

 of the Cape near the coast, it cannot certainly apply to the upland 

 and inner regions which have come under my own observation. He 

 remarks* : — " It will therefore follow that, at a comparatively recent 

 geological period, the greater portion of South Africa was beneath 

 the waters of the sea — that during that time the sandy drift which 

 forms the soil of most of our plains and valleys was deposited, and, 

 when the country was gradually elevated above the waters, a por- 

 tion of salt was still retained by what had been the old sea- bottom, 

 while in many instances the sea-water remaining in hollows would 

 give rise by evaporation to those larger salt-deposits we frequently 

 meet." 



"Without attempting any thing like a thorough refutation, it does 

 seem extraordinary to hear of "sandy drifts" and a ''soil"' deposited 

 by the sea, when the work of ordinary disintegration, weathering, 

 and washing by rain going on at present is so rapid as to deposit in 

 most tracts new soils in our plains and flats in the course of a few 

 generations. The absence of evidences of sea-life, as traces of marine 

 shells &c., in the sands and coil, if so deposited, is altogether inex- 

 plicable, since in other such deposits, as in the great European plain 

 of Eussia and Prussia, thero are abundant evidences of this kind. 

 The present deposits on the surface and to a considerable dej)th 

 have no connexion, I think, with the period of submergence ; and 

 we must look for their origin and that of the salt of the salt-pans to 

 subsequent times, and to causes at present in operation. 



We have a vera causa in the present localization and isolation of 

 these pans. They receive the drainage of the surrounding heights ; 

 and none of it passes away except what may percolate through the 

 lower strata. The various salts from the rocks (sandstones, argil- 

 laceous limestones, &c.), but chiefly from the trappean greenstones, 

 settle in the pans, and are held in solution by their waters. They 

 are therefore but a particular example in the general induction that 

 all bodies of water into which rivers flow and from which no waters 

 pass out are salt. They obtain their salt as the ultimate receptacles 

 of the land-drainage around them. All the constituents necessary 

 for the saturation with salts of such waters are to be found in the 

 metamorphic schists &c. to be collected in fragments in the pans. 



The formation of these pans is most instructive. Deep wells have 

 been sunk on the upper part of the slopes of Du Toit's Pan. One of 

 these must be considerably over 30 feet deep. The dip of the strata 

 is here seen to advantage, and is about 30° towards the pan. This 

 inclination is caused by the elevation of a greenstone porphyry from 

 beneath, forming a more or less regular ring around the j)an, where 

 marginal strata have thus come to be raised. General denuding pro- 

 * ' Report on the Geology of SoviUi Namaqualand,' p. 37. 



