70 Transactions of the South African Philosophical Society. 
clomerate at right angles to the almost horizontal surface, and these 
embrace, in some cases, boulders covered with striations. 
The Dwyka conglomerate in fact forms the ‘“ underclay”’ or 
‘ seat-stone ’’ of the coal seam in which plants actually grew, and 
this has hitherto been supposed not to occur in South Africa—it 
certainly does not occur in the Stormberg coal-field. 
But the Dwyka conglomerate does not only form the floor on 
which, in some cases, first black shale then coal was deposited, but 
through the seam of coal itself, at many levels between the floor and 
the roof, pebbles and boulders also of glacial origin are met with, 
some weighing over a hundredweight each. | 
Then again, what is still more conclusive, the roof of the coal 
at Vereeniging is formed by a bed of conglomerate from 1 inch to 
18 inches thick, and this, though generally of small pebbles of quartz 
and shale of greenish colour, contains strewn through it many larger 
boulders, pebbles, and angular fragments, some of them not only of 
the forms characteristic of glaciation, but also well striated. 
Here is a case of coal being deposited under conditions the reverse 
of what is generally held to be favourable to the growth of such a 
luxuriant vegetation as would be required to furnish many feet of 
coal. For while the basal glacial conglomerate was as yet newly 
deposited, vegetation flourished upon it, then coal became deposited ; 
while this was in progress glaciated pebbles were dropped into the 
seam, and then above all glaciated material was again deposited, 
some of the boulders being partly in the coal, partly in the con- 
glomerate above it. 
The section of the main shaft at Vereeniging is as under :— 
Surface soil 5 ‘ Se ae i sts ci ee 0) 
Grey soft shales (panes) BS ne .. 380°0 
Black micaceous shales and pyrites (omnes beds un to 6 inches 
thick (calamites abundant at base) Se = we .. 380°0 
Conglomerate (glacial) .. sie she 5 “ya B fog 0) 
Good coal .. ste e ate Ex ap ae ans “53, OO 
Black carbonaceous shale iS nee Ag. Le ey, sm ape) 
Floor Dwyka conglomerate, shading into carbonaceous shale at top. 
On the south side of the mine the section of the Cornelia shaft is 
alluvial sand and a i ha bed at base = ae cmos 
Clay shale .. ae A he 3 Me eat eS 
Soft micaceous camuctoned a - i: as $s 6 1067 
Dark grey carbonaceous shales .. Ss a es ai oe ae o) 
Soft micaceous sandstone ve ae st a a fs) 
Dark grey carbonaceous shale .. a aft coe ai vat 4288 
Coarse grit as eH oe, =e at, oe oo ae. 
Dark grey carbonaceous ane a4 _ e 4 o . 210 
Dark micaceous shale .. Re: 24 a a ue $i EEO 
