19

Dawson mapped these beds as Cache Creek, but the amygdaloidal
basalt pebbles in No. 10 indicate that the strata are later than some of
the Miocene lava extrusions. They either belong to a series corresponding
to the Tranquille or are Pliocene. On the track a mile or two north of
Clinton station, there are conglomerates with sandstones and shales like
those at this locality, some of them slightly folded.

i
* GLACIAL AND RECENT DEPOSITS.

More recent than the Tertiary are unconsolidated deposits of boulder
clay, gravels, sands, and silts. Boulder clay or glacial till is widely dis-
tributed. Conspicuous morainal deposits are found at Big Bar lake, in
the neighbourhood of Clinton, and south of 150 Mile House. A flat,
irregular sheet of glacial drift lies over most of the portions of the Interior
Plateau visited, including areas near,the Fraser north and northeast of
Quesnel. A section of boulder clay lying on the east bank of Fraser river
above Quesnel, with interbedded gravels, is given in section 2, page 15.
Dawson! records the finding of glacial striz trending south 30 to 40 degrees
east on all the higher points of the plateau lying 30 or 40 miles south and east

> of Green Timber plateau. The writer found glacial strie trending true

south on top of the plateau near the road between Chimney Creek bridge
and Riske creek and Dawson? records further clear striations trending south
2 degrees east, 8 miles southwest of this place and 6 miles west of Fraser
canyon at an élevation of 3,650 feet, that is on top of the plateau, well
away from Fraser gorge, and he also noted striations trending a few degrees
west of south on Tsawhuz mountain between Blackwater bridge and Prince
George thus indicating the nearly due southward movement of a large
body of ice on the plateau west of Fraser river. The records of glaciation
in the northern part of this district have not been sufficiently studied to
justify drawing general conclusions.

Grey, fine-grained silts occur in the immediate trough of the Fraser
at intervals from Lillooet to Quesnel. They resemble the white silts of
the Thompson lithologically and in their method of occurrence and are
supposed to have been laid down at the end of the glacial epoch.

At Clinton and elsewhere much gravel has been laid down either by
rivers on their flood-plains or by streams connected with glaciers. The
following section taken at a point one mile south of the mouth of Quesnel
river on the east bank of Fraser river illustrates a succession of beds from
the Tertiary,Fraser River formation, up to recent river gravels, in descend-
ing order:

Thickness.

BE. In.

Srp ee eee te AS te PE Oe es eae ee be ee 10
= Gravelly sand, rusty at top..2. 02. oi ee an ie ie oles ee etie ee 9

Coarse-grained, unconsolidated gravel, with boulders up to 1 foot in

diameter, mostly of dense, metamorphosed rocks, a few of granite.... 15
. Grey silt in well-defined beds............ 2... ee eee eee eee eee 135
. Coarse gravel, partly concealed... . 0.0... 6c eee ce eee eee cee cece eens 15
F Sand with seams of Henite ...2201 55-2. ee) Os a IE SS oes = 7
. Sand with a 1-foot bed of gravel at the base.................. 0000 00e- 13
. Concealed down to level of Fraser river. .............0 cece cece = e208

mb wo ib or D100

1Dawson, G. M., Geol. Surv., Can., vol. VII, 1894, pp. 253B-254B. ;
2Dawson, G. M., Geol. Surv., Can., Rept. of Prog., 1875-76, pp. 261-262.