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3. A series of lower clay beds (separated from the overlying 
sands by a foot of pipeclay), and reach a thickness of 64 feet. 
These clays are very compact and even finely laminated, which 
features distinguish them from the more plastic clays of the 
upper portions of the bore. 
Geological Featwres.—The beds passed through are apparently 
of alluvial and lacustrine origin. The thick sand beds with grains 
of uniform size, as well as the limestone, were probably laid down 
under lacustrine conditions. The only indisputable evidence of 
fossil remains was the impression of a spire of a gastropod 
shell in the limestone, but too indefinite to indicate its generic 
affinities. The geological horizon of these beds can, there- 
fore, only be surmised from their lithological features. They 
certainly do not correspond with the Pliocene clays and drifts of 
the Adelaide Plains. The fine, clean sands, the (?) fresh-water 
limestone, and the highly indurated condition of the lower clays 
are points of difference. 
In examining some of the material microscopically, 1 observed 
small siliceous granules which had to all appearance been formed 
from colloid silica. 
The River Torrens, 1n passing between North Adelaide and the 
city, cuts through the ridge referred to at right angles, and 
exposes the marine Miocenes in its banks. The travertine crust, 
which is a marked feature of this ridge from North Adelaide to 
Enfield, probably indicates an extension of the Miocene beds 
in that direction. Whether they actually extend in a northerly 
direction as far as the bore now described has been left unfortu- 
nately an undecided point, as the bore was not deep enough to 
settle the question. 
The beds passed through in the Enfield bore certainly exhibit 
some resemblance to the variegated clays and sands of the 
Miocene beds at Hallett’s Cove. It is not unlikely that they 
represent the eastern fringe of an Upper Miocene formation that 
once, more or less covered the plains to the westward, but has 
been removed by the denuding forces that immediately preceded 
or were coincident with Pliocene times. 
[For particulars of the Boring see next page. | 
