SOUTHERN AFRICA. 299 
figured, plain, and ftriped, zoned and ftaladitlcal ; not thinly 
fcattered here and there, but in fuch quantities that, judging 
by thofe few banks which were uncovered with water, a wag- 
gon-load might be collected in a few hours. Thefe beds con- 
fifted generally of round and oval pebbles, fome having a black 
ground, others light-brown, and others chocolate color. Thefe 
were inlaid with other fmall, white, quartzy pebbles, forming, 
on the fmooth furfaces of the former circles, flripes, and irre- 
gular fpots and lines. They appeared to be of that defcription 
of aggregated ftones called, by fome French mineralogifts, va- 
riolites, and to which Mr. KIrwan has propofed to give the ge- 
neral name of porphyrites. The white parts grew as it were 
into the colored bafe, and adhered to it fo clofely as not to be 
eafily feparated. It is remarkable enough that this fhould be 
the only river in Southern Africa, at leaft between it and the 
Cape, in which ftones of this nature are found. According 
to the relations of Vaillant and Patterfon, the agates extend 
down the bed of the river as far as its mouth, on the weftern 
coaft ; but neither of thefe authors makes any mention of the 
fpotted ftones which, had they been there, muft have obtruded 
themfelves on their notice, being no lefs fmgular and beautiful 
than they were numerous ; whole banks were entirely com- 
pofed of them and the others above mentioned. They occur- 
red of all fizes, from a line to a foot in diameter, generally 
rounded and fmoothly poliftied by attrition in their pafTage 
down the river. The rocky banks were mafles that apparently 
were compofed of clay and mica, containing alfo a confiderable 
portion of the oxyd of iron. The angles of thefe were like wife 
rounded off", and their furfaces worn fmooth by the adion of 
Q^Q^ 2 the 
