The New York herald., 1870-10-30
SCIENTIFIC RESEARCH.
Geology of the Dinmondiferous Tracts OF
South Africa, by DIR. John Shaw, Coles
From the Cape Monthly MagaZine.1
TILE MIDDLE YAAL REGION

IFrom the Cape Monthly Magazinel
THE MIDDLE yAAL REGION.
In the month Of February, 1859, my friend w. d.
Chalmers. Esq, Civil Commissioner and Resident
Magistrate OF Clanwilliam published in the ora
hanls 1oacn Jou,nol statistics of the various dia.
monds (so far as remember, l2l) which had come
under his notice when he was Civil Co nmissioner OF
Hope Town. About the same time had the prvi-
ege Of publishing through the columns OF the same
paper an account Of the geological structure OF the
Vaa region along the line where diamonds were
James Gregory's denial Of the verltability OF tie dis
covery OF diamonds. on various grounds. mainly
geological and neurological, after journey OF ex-
the finds OF surface diamonds have increased,
the stretch OF country supposed to be
present moment systematic digging ana
washing for diamonds are being carried on with an
enthusiasm which success alone can have created,
By upwards of one thousand white men In different
parts Of the Vaa region but principally at Kipdrift
near Pniel.
mondirerous tracts and goes back to the gloriousy
providential accident which brought the first dia.
mond through varying fortunes nearly four years
ago, into the hands OF DR.. Atherstone OF Graham's
Town Ia gentleman so worthy associated Win the
natural history Of south Airlcal, we We cannot but
OF the grand discovery, and that she owes nothing
to the enterprise and knowledge of the various
emssares who have come to the country as investi.
tigators and prospective appropriations We nope
therefore, that our government Will see that the col
onlsts OF south Africa may have their individual
rights conserved and recognized far as possible;
that they may enjoy the full Deneht OF discovery
which seems to have turned up at the necessitous
moment to resuscitate our falling prosperlty-a dis
covery with when the colunlsts themselves have
been identified from the very beginning In
itae N the 9n'S Soa 1toan erus' agasi,se @ po Noe"
on the geology OF the Vaal, as far
as had then investigated Its banks am now in
position TO give more complete account from FUR
ther observations made during my vacation In the
month Of July last. find have nothing TO modify
in that notice; for up the whole course Of the vaal
to Hebron, where inc hali-caste squatter Barend
Boems tribe IS located, there is the same general
development Of trappean metamorpnc anu anu con-
the surface soil is different IN various parts; but in
regard to the geological structure there Is evidence
wherever diamonds have been found, OF the charac
ter which have now stated. In the "Note'' said
that had found granite IN the form OF nodues in
OF the Vaal Nowhere could then discover any
granite formation; nor indeed was able to trace
the boulder In question to Its source. have, how
ever succeeded at last in finding trap conglomerate
almost breecia) on the Pniel side OF the kpdrt
Dlggings, and this rock has mainly Embedded in 1t
granite fragments, some, too, Of considerable size,
none OF when are however, very apparently water
worn. detected pure granite formation but SVEN
lite Is, however, developed extensveiy ana seems 10
very singular rock appears In the shape OF lsoa-
ted boulders on the SUBMITS Of kOpjes, and espe-
| cally Of the celebrated Old Kopje. This take to
| be graphic granite (pinary grantel or what Dana
would call granite consisting solely OF quartz and
large crystals OF felspar Above the syenlte Is the
| trap conglomerate IN some places; In Others are
amygdalOlds and. protrudlng through these again,
| basat assuming everywhere the hexagonal struc.
ture and arising up in some places into insulated
| and c0mpacted columns. The b!sat forms the
features OF the landscape ana a5 Tar as eye can see
Won have an unineresting anc unpicturesque repe-
ftion of trapean kopes. In some OF the kopes there
are the remains or strattfed 'rocks-clay states,
sandstone chalk Tor something very like ll-whlcl
are evidently the last vestiges OF vast series OF
| eedlmentary strata, which formerly covered the
| whole present contour; but have gradually given
way TO denudaton ana cataclysm, leaving the
| monumental basalt which was infused into them
| and moulded there. ,-
nj Klpdriit and with Few additions (mainly su.
percumbept) Of the whole rock series OF the Vaal
| On the summit OF the k0pies, and, as matter OF
! course In the crevces between the bnsaltic boul
| ocrs Is an alluvia gravel. In this are i0und the
| diamonds, and on the surface sonle nave peer
foupd-lndicators as IN the Old Kopje OF klpdrift
| of the wealth beneath. The pebbles OF sandstone
ouartzte crystalline sandstone, granite, cay slate
agate peridot tourmaline, iron pyrtes garnet, gar
i net sninel &c. which compose tha alluvium, art