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feature, especially considering the fairly high altitude of the area and the
small amounts of flood-water at the present time. The area probably stood
considerably lower during parts of Pleistocene time, in order to permit of
such extensive and rapid melting of the ice as the amounts of stratified
deposits indicate, but nothing is definitely known regarding the amounts
of uplift and depression of the region.

Interglacial deposits formed during a period of temporary recession
of the ice—formerly considered by the present writer as absent in the
area—were found at a number of places. The most remarkable occurrence
is on the south bank of Lightning creek about 13 miles above the junction
of Swift river and opposite the old Cold Spring House on Cariboo road,
where the following section in descending order is exposed:

Feet
Hoan deniverneravelsserere rere osteirerrr sys eclereiieoiisleinlaisicvareists 1
BOUT STG] tyne ee eT ecTe eral Fee e rate Stata e ov stnt ota corai nee eve Tardtatey ctotes 10
ID hantiee San a oa ORD Ooo Goad RCO EUG OPO OD STL O OP OD MONET COR ed onncubneeGe ann 1
Stratified silt and sand passing into stony clay at top...........-..-..05- 10
ibYonio GeO Pagadeh adhd ooRbOpea os oo GboesoD OCH OSBGSS CEE ceEEoocomeonoarnd 5
Strativedselacialisiltummnresceeterie ricki ieee eek ierrerectete RAs wardens 1
@xadizedeoravel sumer eee ei ieee elioeie eee lelascteioier citeecisielars a
Som, Gill dkay incl rarneh easoodadoocsoobaccnopoddsosusgsd0dadaugdd™ 3

The lignite is composed of carbonized tree trunks and branches and
is reported! to have consisted, at one time, of a seam 6 to 10 feet thick,
but is now mostly eroded away. Although there is a black clay or soil-like
layer at the bottom, which can be traced along the bank for nearly 200
feet, it is not certain that the lignite is in place. There are numerous
fragments of the lignite in the upper boulder clay immediately above the
main deposit of lignite and in the boulder clay exposed along the creek
for one-half mile or more downstream. The fragments in the boulder
clay show no evidence of shrinkage and, therefore, the wood must have
been altered to lignite before it was included in the upper boulder clay.
The lignitized wood is too much altered to permit a determination of the
kinds of trees from which it was formed, so that there is no fossil evidence
of the age of the deposit. It may have been formed in interglacial time,
but if so, it seems remarkable that such complete alteration should have
taken place. More probably it is of pre-Glacial (late Tertiary) time, and
gathered in the valley bottom as masses of driftwood, to be converted
later into lignite, which escaped first glaciation to be exhumed and trans-
ported by a later advance of the ice. In any case, however, there is
fairly definite evidence at this locality of more than one advance and
retreat of the ice.

In the central part of Barkerville area drilling reeords show at several
places the presence of pay-streaks that are overlain and underlain by
glacial drift. These indicate a period of stream erosion in interglacial
time. Apparently the streams did not cut down to bedrock in the lower
parts of the valleys, for the pay-streaks are well above the bedrock but
are 40 to 80 feet from the surface. A remarkably rich pay-streak of this
character occurs at Eightmile lake, where pay gravels overlain and under-
lain by boulder clay have been mined by hydraulicking. The gravels at
the surface of the lower boulder clay at Kightmile lake are somewhat

1Dawson, G. M.: Geol. Surv., Canada, Rept. of Prog. 1876-77, p. 145.
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