the other hand, one small nugget, from the Peacock lease, com-
posed*of gold, pyroxene and a small amount of serpentine sug-
gests that it might have come from gold mineralization in ser-
pentine; therefore the possibility of finding a gold-bearing
lode in serpentine must not be ignored completely.

Several gold nuggets containing feldspar but no quartz
were recovered from Alice Shea Creek. The feldspar is moder-
ately coarsely crystalline. The only rock of similar composi-
tion is an aplite dyke in slate near the head of Wheaton Creek.
Neither pegmatite dykes nor feldspatic quartz veins were seen
anywhere, but it is strongly suggested that one, mineralized
with gold, was the source of some of the placer-gold on Alice
Shea Creek. The white feldspar showing good cleavage might be
a valuable marker for a dyke or vein that supplied some of the
placer-gold.

The outcrops of auriferous lodes were weathered and eroded
during the Tertiary. The gangue of any auriferous veins was
broken down and the host-rock disintegrated. After a consider-
able time hillside eluvial placers might be expected to form
near the outcrops of any gold-bearing deposits. With down-
hill soil- creep and surface rainwash, gold and other resis-
tant minerals would migrate downhill and be further concen-
trated in placers in the creek-bottom. It is believed that
most of the placer-gold was released and formed gold-bearing
stream-placers prior to the Pleistocene because the amount of
post-glacial bed-rock erosion is so slight that little or no
gold would have since been set free. The absence of hillside
eluvial placers at present is explained by the heavy run-off
that no doubt preceded the glacial epoch and the destructive
erosion by glacial ice.

Alice Shea Creek flows only 10 to 15 feet below the bot-
tom of the late Tertiary creek. Gold was concentrated in the
gravel, and on bed-rock in the bottom of the Tertiary creek.
Although at present, bed-rock on the valley-sides is overlain
by glacial boulder-clay, the Pleistocene ice erosion apparent-
ly was not sufficiently great to disperse all the gold. The
absence of a cirque at the head of the creek probably accounts
for the lack of erosion. In post-glacial time Alice Shea
Creek cut below the Tertiary valley-bottom and reconcentrated
any gold that was in the boulder-clay or that lay on, or in
the bed-rock. Consequently the gold concentration is on bed-
rock or in the shallow post-glacial gravel of the present
creek.

The rejuvenation of Wheaton Creek and its incision to-
wards the close of the Tertiary resulted in the concentration

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