Carboniferous Glaciation , Etc .— IFA^e. 303 
feet in a matrix of friable clay. 1 In many regions where the 
older rocks, on which the Talchirs rest generally unconform- 
ably are newly exposed, they are foundto be worn with striations 
and grooves; and in the great Indian Desert which stretches 
from the Arvali Range to the Indus river, Mr. R. D. Oldham has 
fonnd, about Pokran (N.lat. 26° 55'.), a country of porphyry 
and syenite completely covered with scratches and striations. 
The same was observed by W. T. Blanford in 1875. 2 On the 
surface of this lies a tenacious mass of glacial origin, consist¬ 
ing of gravels of porphyry and syenite, which Oldham con¬ 
siders to be till or “ moraine profonde.” In the near neigh¬ 
borhood and in unmistakable connection with these de¬ 
posits are the Talchir boulder beds themselves, in which he 
found one mass measuring 10 by 7-J- by 3 feet, of a rock simi¬ 
lar to none nearer than the Arvali mountains, 150 miles away 
to the southward, from which he believes it to have been 
transported. Of the further extension of the Talchirs I shall 
treat when considering their probable age. It may be noted 
here that they contain few fossils, and these in the upper 
stage. 
AFRICA. 
Concerning the geological details of South Africa 
much less is known than of any other region with which we 
have to do. A vast sandstone region occupies the entire 
center, and is fringed by older formations, old slates, crystal¬ 
line and Devonian rocks. This so-called “ Karoo” formation 
extends over the north part of Cape Colony, the Orange Free 
State, Transvaal, and the deserts lying westward, and presents 
a series of sandstones and shales, interrupted in places by 
eruptive rock, which reaches a maximum thickness, as shown 
by T. R. Jones, of nearly 10,000 feet. The Karoo formation 
rests, for the most part, or in some regions, at least, 
conformably, on the Table Mountain sandstone, containing re¬ 
mains of Lepidodenron and Calamites, and generally regard¬ 
ed as Devonian, though considered recently by Cohen 3 as be- 
1 R. B. Foote. Notes on the geology of the neighborhood of Madras. 
Rec. Geol. Surv. India, hi, 1870, pp. 11-17. 
2 W. T. Blanford. Additional evidence of the occurrence of glacial 
conditions in the palaeozoic era, etc., Quart. Jour. Geol. Soc. London, 
xlii, 1880, pp. 249-260. 
3 E. Cohen. Geognostisch-petrogranhisclie S kizzen aus Siid- 
Afrika. N. Jahrb. f. Min., Beil. Bd. v. Heft. 1, 1887, pp. 195-247. p.vm, 
2 ix. 
