336 THE GEOLOGICAL FORMATION OF GERMAN S.W. AFRICA. 



recent deposit of Calcareous Tufa is observed lying on the surface 

 rock. It consists of varied fragments of all degrees of coarseness, 

 cemented together with Carbonate of Lime. This latter is most 

 probably derived from the Archaean Limestones which have been 

 denuded, and from the decomposition of the Lime Felspars of the 

 basic-intrusive rocks. 



With the exception of this land deposit, I have seen nothing 

 more recent than the Glacial Conglomerate, from which I have 

 come to the conclusion that this part of the country has been a 

 land surface since about carboniferous times. 



At Warmbad there is a hot spring from which the place derives 

 its name. Water of fairly high temperature (about as hot as the 

 hand can bear it) flows in considerable quantity from apertures in 

 the granite. It is not used as drinking water, as it contains 130 

 grains of soluble salts per gallon — mostly chlorides and sulphates 

 of soda and magnesia. Potash is also contained in smaller 

 quantity. 



Attempts are made to use the water for irrigating garden plots, 

 but with poor success. Whenever the ground is allowed to dry 

 a white efflorescence is observed on the surface. 



A considerable quantity of gas is also ejected from the spring. 

 Some of this was collected and roughly tested. It possessed the 

 properties of Nitrogen, but there were no means of making any 

 elaborate tests. Argon is a probable constituent of this gas. 



(2) The coast belt from Luderitzbucht to Pomona. — A visit 

 to this part of the world will reveal the first solid crust 

 ever formed on this earth. The wonderfully tumbled mixture of 

 Archaean rocks — Granite, Gneiss, Quartzites, and Mica Schists — 

 points to one thing. The first cooling of the outer layers of molten 

 matter forming our earth at that period of its evolution resulted 

 in solidification and subsequent weathering of the solid portions of 

 crust under conditions probably far more favourable to rapid de- 

 composition of minerals than those which obtain at present. Sedi- 

 mentary rocks were formed and then came a disturbance of equi- 

 librium and the solid portions were engulfed in the molten matter 

 forming the rest of the globe. This is exactly what one would 

 expect to have happened several times before the crust finally 

 became strong enough to resist any internal disturbances. 



The whole coast belt, several miles wide, is a portion of a vast 

 Titanic pudding, whose ingredients have been well stirred. 



Journeying south from Luderitzbucht, one sees rapid alterna- 

 tions of Granite and Gneiss, shewing all degrees of lamination, 

 Mica Schists with silvery cleavages and very compact Quartzites. 

 In the neighbourhood of Luderitzbucht the Granite and Gneiss 

 preponderate while near Pomona the Quartzites become more 

 numerous. 



The baking process to which the sedimentary rocks were sub- 

 jected has resulted in the formation of variously coloured rocks, 

 the colouring matter being mostly the oxides of iron. Even 

 Quartz reefs in the sedimentary rocks have participated in the 

 baking and have in parts become impregnated with oxides of iron, 

 generally red Ferric Oxide. All gradations from a ferruginous 



