516 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 25, 
Dr. Sutherland holds that it is obviously a brecciated conglomerate, 
derived from aqueous deposit, rather than an igneous porphyry, and 
he urges the following reasons in justification of this view. 
In the first place, he has sought for years for the vent through 
which such a vast mass of erupted rock could have been thrown. 
Where such a mighty mass is concerned its eruption from beneath 
could not have been effected without leaving very obvious marks of 
voleanic disturbance. There are no such indications anywhere. 
Mr. Bain has suggested the possibility of some such vent having 
existence about the sources of the Orange river. In that district 
there is certainly no trace of such rock-convulsion. 
Then the abundant ripple-markings, and the gradual transition 
into fine shales and sandstones of unquestionably aqueous origin, 
are incompatible with the theory of volcanic or igneous formation ; 
as is also the rubbed condition of the fragments, and the absence in 
them of all signs of fire-action or fusion. 
And yet, again, there is the transport of the vast ponderous 
blocks to long distances, and the’ scorings and groovings of the 
sandstone upon which the Boulder-clay formation rests, to be ac- 
counted for. 
On the whole, these circumstances seem to indicate that the 
constituents of this Boulder-clay have been derived from the super- 
ficial denudation of older rocks by aqueous agency, and that it has 
assumed its existing relations to the other rocks while in the con- 
dition of a moist and plastic mass. In all probability the finer 
shales, containing impress of the ripple-marks, were formed during 
periods of approximate repose; and cataclysmic violence and dis- 
turbance had ceased altogether when the deposit of such beds as 
the Maritzburg shales began. 
Dr. Sutherland inclines to think that the transport of vast 
massive blocks of several tons’ weight, the scoring of the sub- 
jacent surfaces of sandstone, and the simultaneous deposition of 
minute sand-grains and large boulders in the same matrix, all 
point to one agency as the only one which can be rationally ad- 
mitted to account satisfactorily for the presence of this remarkable 
formation in the situations in which it is found. He believes 
that the boulder-bearing clay of Natal is of analogous nature to the 
great Scandinavian drift, to which it is certainly intimately allied 
in intrinsic mineralogical character; that it is virtually a vast 
moraine of olden time; and that ice, in some form or other, has 
had to do with its formation, at least so far as the deposition of the 
imbedded fragments in the amorphous matrix are concerned. He 
dwells particularly upon the fact that Prof. Ramsay has already as- 
signed certain breccias of Permian age to glacial periods and agency, 
and that there is good reason for referring the coal-bearing shale 
of Natal, into which this boulder-bearing clay passes almost imper- 
ceptibly, to the Permian system. 
For these various reasons, Dr. Sutherland submits that the 
Boulder-clay formation of Natal should be classed with the Permian 
glacial breccias of Prof. Ramsay. 
