REVIEWS. 
Tue Grotocy or PonDoLaNnn. By Ay is Dy Dorm, Disc.) Expl. 
Cape Sheet 28. Geological Survey of the Union of South 
Africa. pp. 44. 
(Meus unassuming little memoir of only forty-four pages and the 
accompanying map contain the record of a piece of work of 
really remarkable character when we take into account the nature of 
the country. It comprises a description of the geology of Pondoland 
and portions of Alfred and Lower Umzimkulu Counties, Natal. This 
is a region of high plateaus, deeply dissected by river gorges, often 
with vertical sides; in parts covered by dense forests and only 
sparsely settled ; much of it is native reserve and very little known. 
Nevertheless, Dr. Du Toit has worked out the geology in much detail, 
and has discovered many interesting features. The geological 
formations represented are as follows: oldest of all are the 
crystalline dolomites of the Marble Delta on the Umzimkulu River, 
in Natal; then come granites, usually gneissose, and amphibolites 
of pre-Cape age. The Cape system is represented only by the Table 
Mountain sandstone, the upper part being absent. The Karroo 
series is apparently quite complete and very thick. Above this come 
Lower Cretaceous sandstones and conglomerates, the Embotyi 
beds, followed by the well-known fossiliferous marine Upper 
Cretaceous, generally known as the Umtamvuna series. The 
author says these beds do not occur at the locality from which the 
name is taken,and he renames them the Umzamba beds. No Tertiary 
strata have been found. The correlation of the sandstones of Natal 
with the Table Mountain series, for long in dispute, may now be 
considered as established. This formation: is in many ways 
remarkably like the Millstone Grit. The Dwyka conglomerate is 
well developed, and it is considered that in southern Natal its thick- 
ness may be as much as 1,500 feet. 
The tectonics of the country are very fully discussed, and the 
existence of some very important dislocations is established, such as 
the great Umgazana and Egosa faults. However, in spite of the 
numerous items of interest that might be mentioned, we can only 
afford space to refer to one special problem, namely, the general 
nature of the structure determining the coast-line of this area. It 
is here shown that the view upheld by Suess, among other geologists, 
that the coast-line 1s a great fracture, is untenable. The present 
work confirms Penck’s idea that the principal factor was a mono- 
clinal flexure extending along the Lebombo range and then striking 
S.S.W. through Zululand and along the coast of Natal. Its axis 
just clears the shore of Northern Pondoland, but is brought inland 
again by transverse faulting ; it must, however, again run out to 
sea further south. The age of this flexure is not certainly fixed : 
it is post-Stormberg (i.e. post-Liassic), but its relation to the 
Cretaceous strata is unknown. Another feature of interest here 
described is the terrace of marine denudation traceable for a long 
distance at 1,000 feet above sea-level ; other similar shore-lines are 
traceable up to 2,000 feet, but the latest movement was one of 
