Geology Reference
In-Depth Information
Painted Hills in eastern Wheeler County is a succession of ancient soil profiles developed in the John
Day Formation (photo courtesy Oregon State Highway Department).
ate John Day period. Once thought to be extinct,
Metasequoia was re-discovered in China and brought
to Berkeley by paleobotanist, Ralph Chaney in the
1930s.
The third section of the Monument at Picture
Gorge and Sheep Rock 38 miles west of John Day tells
the story of life here 25 million years ago. The narrow
gorge was so named because of ancient Indian picto-
graphs painted onto the basalt. Probably one of the
most scenic localities in Oregon, the gorge cuts
through 1,500 feet of basalt in numerous flows separat-
ed by occasional soil layers. A small cap of hard
Miocene basalt protects the softer, buff-colored volca-
nic tuffs of the upper John Day beds making up Sheep
Rock, one of the most familiar sights of the National
Monument.
The display areas of the National Monument
are in three different locations beginning with the
Palisades at Clarno where Eocene mudflows of shales,
siltstones, conglomerates, and breccias are exposed.
These mudflows or lahars are particularly distinctive,
eroding into steep cliffs, spires, and columns along
vertical fracture lines in the softer sediments. This is
the oldest section of rocks in the Monument.
At the Painted Hills north of Mitchell a
badlands physiography reveals colorful exposures of
rust red soils alternating with yellow, and light brown
tuffs of the John Day Formation. Evidence of plant and
animal life 30 million years ago can be seen in the few
fossil remains found. The Bridge Creek fossil plant
locality, famous for its Metasequoia leaves, is nearby.
Grand Canyon of the Snake River
Beginning at the oxbow on Oregon's eastern
border, the deep, narrow Grand Canyon carved by the
Snake River cuts between the Wallowa Mountains of
Oregon and the Seven Devils Mountains of Idaho as it
journeys northward. From the summit of He Devil
Peak in Idaho to the depths of the Snake River bed,
Hells Canyon measures nearly 8,000 feet deep, which
