Evidences of Epeirogentc Movements.—U pham. 169 
for explaining its causes, aside from the astronomic theory, 
of Croll, which does not agree with the late time of termina- 
tion of European and North American glaciation, it is ex- 
tremely unlikely that this most unique great event of geology, 
the accumulation of continental ice-sheets, could be repeated 
two or more times, with intervening complete departure of 
the ice. . 
A PERMIAN GLACIAL INVASION. 
By Epson S. Bastin, Ann Arbor, Mich, 
The memoir by Mr. G. A. F. Molengraaf* on the “Geology 
of the. Transvaal,” which recently appeared as a bulletin of 
the Geological Society of France, contains not only much ma- 
terial descriptive of a country which seems to offer unusual 
attractions to the geologist, but contains much that is of 
especial interest to the student of glacial geology. 
It appears that the basement formations of the Transvaal 
which are of lower palaeozoic age, (the exact age is not yet 
determined) are overlain unconformably over the whole south- 
ern half of the Transvaal by the Karroo series, divisible into 
the upper and lower Karroo formations. 
The lower Karroo beds are conglomerates, in some regions 
very coarse and unstratified and in other regions composed of 
finer materials and stratified. Mr. P. C. Sutherland, a number 
of years ago, advanced the hypothesis of the glacial origin of 
this formation and assigned it to the Permian, and the work 
of Mr. Molengraaf seems to place the matter beyond doubt. 
Not only do the unstratified portions of the Karroo conglom- 
erates present all the characteristics of glacial till in their 
physical and lithological heterogeneity, but in many localities 
the surface of the, underlying primary rocks have been found 
to be polished and scored in a manner corresponding exactly 
to the scorings left by the ice of our Pleistocene glacial in- 
vasion. Roches moutonnées are also found in their typicai 
forms. 
In addition to this, the stratified portions of the Karroo 
conglomerates which, as a rule, lie to the northward of the 
* Bull. Soc. Geol. de France. Tome i, 1901, pp. 13-93. “Geologic de la 
Republique Sud Africaine du Transvaal.” par G. A. F. Molengranff. 
