Fauna and Stratigraphy of the Stormberg Series. 479 



almost entirely of land animals, distributed evenly throughout its mass. 

 Great numbers of bones of mammals occur locally - - mostly belonging 

 to forms abounding on steppes and grassy plains. 



The consolidation of such a deposit would very conceivably result 

 in such a rock as the Cave Sandstone. The grains in loess, like 

 those of the Cave Sandstone, are not rounded as those of desert sands, 

 but are described as "angular or sub-angular". One striking diffe- 

 rence, however, is in the much greater abundance of hydrated silicate 

 of alumina in the loess as compared with the Cave Sandstone : another 

 in the number of tubules ''marking the site of the roots of countless 

 generations of plants" ; and a third in the absence of land-shells in 

 the Cave Sandstone. 



Taking into account its various peculiarities, von Richthofen con- 

 cluded that the loess of China is the product of aeolian influences 

 acting during periods of long duration and under different conditions 

 of climate, of which three are distinguished in North China: (1) an 

 erosion period, in which the surface of the country was sculptured 

 by erosion and denudation into the figure it still retains beneath the 

 covering of loess; ( 1 2) a Steppe period, in which the conditions of the 

 saline steppes of Central Asia were extended over the whole of Northern 

 China; (3) a loess period, now existing, in which the former Steppe- 

 districts become converted into Loess-districts by the gradual accu- 

 mulation of dust at the surface, the dust being held in place by the 

 growth of vegetation. This theory of the formation of the loess can 

 be accepted for Northern China; but it does not fit exactly all the 

 requirements of Cave Sandstone formation. 



In the first place there is the difference in composition between 

 the two rocks. The Cave Sandstone is felspathic ; but the felspar is 

 but little decomposed and there is no such alteration product as 

 hydrated silicate of alumina in any large quantity. Sand grains play 

 the predominant part in the formation of the deposit. The chemical 

 nature of the sandstone and the comparative angularity of its frag- 

 ments indicate fairly arid weathering of the original land from which 

 the material was derived. In this, there are not true "loess-conditions". 



Secondly, there is no indication in the Cave Sandstone of the little 

 tubes representing former grass-roots, nor any sign of extensive vege- 

 tation. 



Silicified trunks of trees have been recorded from various localities 

 in the Cave Sandstone, as for instance at Morija and Masitisi in Basuto- 

 land; but most of the occurrences, together with the doubtful occur- 

 rence of coaly material near Belmore, Barkly East, seem to be in the 

 upper, sometimes laminated portion of the deposit. 



