366 
ON THE METAMOEPHOSIS OF EOCKS IN THE CAPE 
TOWN DISTEICT, SOUTH AERICA. 
Et De. E. N. Eubidge. 
I gave, in a paper in the February number of the ' Geologist,' a 
general view of the facts in the geology of this country which have 
led me to believe that the metamorphosis of rocks is due to a slow 
and gradual change in their constituents ; of which change water is 
one of the chief agents, and the internal heat of the earth not a ne- 
cessary adjunct. 
I now propose to describe more particularly those relations of the 
quartzite with the palaeozoic rocks, a careful examination of which 
has rendered necessary an entire reconstruction of the geological map 
of the country. That map, published in the Transactions of tlie G-eo- 
logical Society, was the work of an able man, and the evidence on 
which the Devonian (Upper Silurian, Bain) was separated from the 
Clay-slate formation was (so far as I have been able to verify it), I 
believe, such, that he would not have been justified in coming to an- 
other conclusion by any generally admitted principle of the science ; 
for this reason, I invite the criticism of European geologists on my 
facts and inferences, and their aid in solving many difficulties which 
still remain unexplained. 
I stated in my former Paper that the plains and lower hills and 
valleys of the coast region, extending from Cape Town to the mouth 
of the Fish Eiver, were formed of blue slaty and sandy rocks. These 
were all referred to one formation by Lichtenstein. 
Dr. Krauss, an eminent botanist and geologist, states that he made 
repeated sections of the country, from the coast to the Karoo, and 
always found the clay-slate (Thonschiefer und Grauwackeschiefer) 
occupying the plains and valleys, and the quartzose sandstone or 
quartzite (Bunter-Sandstein) the mountains. On Zwartkops heights 
and the Von Stadens river bergen, he remarks this was notably the 
case. Dr. Atherstone, in a section through the district of George, 
could find no reason for separating the clay-slate from the Devonian. 
Mr. Bain agrees with these authorities as to the identity of the slates 
as far eastward as the mesozoic estuary of the Gamtoos river. In 
his map he shows the clay-slate, interrupted (as also mentioned by 
Krauss) by masses of granite, and surmounted by sandstones, ex- 
tending from Cape Town to the edge of the mesozoic rocks, — a point 
corresponding to the Kabeljouw river's mouth in the sketch. 
Lichtenstein, Bain, and Krauss therefore concur in believing the 
clay-slate and quartzite of the region between the Kromme and Ka- 
beljouw rivers to be respectively identical and continuous with those 
of Cape Town, where the highly inclined beds of slate are surmounted 
by nearly horizontal sandstone. Mr. Bain, differing with the others, 
makes both cease here. I have little doubt of the continuity of the 
slate from Cape Town hither. I have none (as I shall presently 
