6 S. &. EMMONS 
drainage channels, whose decay he ascribes to the agency of 
meteoric waters remaining long in contact with the rock. The 
area on which the town of Barberton is situated is sixteen by eight- 
een miles in extent. Throughout these areas are what are called 
‘““Tongas,” that is water-washes, with intricate drainage channels 
and perpendicular walls, not unlike the Bad-land topography 
of the West. The depth of this decomposition may reach 200 
feet, while on the steep slopes of adjoining hills, and in bowlders 
rolled down onto the surface, the granite is hard and undecom- 
posed. The same decay is found in other feldspathic rocks. 
Primary formation.—Under this head are included granites, and 
a series of schists called by Schenck the Swasi-schists, because 
of their abundance in Swasiland to the south and east of the 
De Kaap basin. 
The granite is described by Molengraaf as consisting of micro- 
cline granite and of tonalite (plagioclase granite), muscovite being 
developed in the former as an alteration product of feldspar. 
Furlonge remarks on its light color and the absence of dark 
minerals in the De Kaap district. I find no explicit statement of 
the relative age of granite and schists, but Molengraaf says the 
schists rest upon the granite, and Schmeisser describes them as 
dipping away from it in three directions. For the most part 
these schists appear to be compressed into close folds and stand 
at steep angles, but in some cases they occupy a nearly horizontal 
position. While classed under a single head, it does not appear 
impossible that they may belong to two distinct series of rocks. 
According to Molengraaf they consist mostly of quartz-sericite 
and actinolite schists, and in places of conglomerates and sand- 
stones, also carrying sericite. Schmeisser describes them as in 
part metamorphosed beds of sedimentary origin, such as slates, 
quartzites and magnetite-quartz (calico) rock, but to a much 
greater extent of metamorphosed schists with greenstone dikes 
and sheets, the latter altered into hornblendic, chloritic and ser- 
pentinous schists. Molengraaf speaks of quartz-porphyry dikes 
in the schists around the granite. Schmeisser says gold-bearing 
veins occur wherever the Swasi formation is developed. They 
