PLATE 1. A, Yukon Valley, looking downstream from international bound-
ary; B, Yukon River at the mouth of Washington Creek;
C, Panoramic view of the narrows of the Yukon River
at the mouth of Woodchopper Creek.--
2. A, Valley near the headwaters of the Charley River; B, Undif-
ferentiated (possibly upper Silurian) limestone along
the west bank of the Yukon River just above Takoma
3. A, Contorted feldspathic quartzite in Birch Creek schist; B,
Augen gneiss, intrusive into Birch Creek schist...
4. A, Cambrian limestone and associated rocks on the north bank
of the Yukon River just north of Calico Bluff; B, Crinoids
in crystalline limestone of Silurian (?) age from west slope
of Loop Mountain, Yukon Territory----
5. A, Fossiliferous Middle Devonian limestone in Woodchopper
volcanics, as seen along the north bank of the Yukon
River opposite Woodchopper; B, Woodchopper volcanics
along the northeast bank of the Yukon River below the
mouth of Woodchopper Creek.
6. A, Lower Mississippian chert formation on the east bank of the
Yukon River just below the mouth of Shade Creek; B, El-
lipsoidal greenstone in Woodchopper volcanics on the north
bank of the Yukon River above Woodchopper.---
7. A, Undifferentiated Paleozoic greenstone in bluff on the west
side of the Yukon River at the mouth of Mission Creek;
B, Lower Mississippian volcanic rocks along the east bank
of the Yukon River above Circle...
8. A, Vertical beds of chert at north end of bluff on the west side
of the Yukon River below Takoma Creek; B, East side of
Calico Bluff, on the Yukon River below Eagle....
9. Enigmatical fossils in Mississippian or Pennsylvanian transitional