Geology Reference
In-Depth Information
In the Lava Cast Forest on the northwest flank of Newberry Crater, lava has surrounded trees which
burned to leave a hollow mold (photo courtesy of Oregon State Highway Department).
up by cinders, a rugged volcanic panorama covering
almost 10 square miles of lava field can be seen.
As successive, thick flows from this volcanic
center between Newberry Crater and Lava Butte spread
sluggishly across the landscape, pine forests much like
those here today were engulfed by the slow moving
lava. Some trees remained upright while others fell
over after being buried by the molten lava. Once
enclosed in the flow, the trees burned slowly leaving a
mold the size and shape of the trunk. Contact with the
trees chilled the lava in the flow into cylinders around
trunks. Once the lava had receeded, these cylinders
were left standing above the surface flow. The Lava
Cast Forest which resulted is encased in the rough
black lava.
Newberry Crater, with a large caldera, lakes,
obsidian flows and domes, and pumice and cinder
cones, provides a view of spectacular volcanic geology
in a concise area that is easily accessible. In the spring
of 1991, Newberry Volcanoes National Monument was
dedicated. This new monument which includes Newber-
ry Crater, Lava Butte, Lava River Cave, the Lava Cast
Forest, and Paulina Peak sets aside an area for viewing
and studying a wide variety of volcanic features.
A low profile, shield volcano, Newberry is 40
miles long and 20 miles wide and contains Newberry
surrounding plains, offers an impressive panorama of
the Cascades and surrounding buttes of the High Lava
Plains, as well as a glimpse of the winding canyon of
the Deschutes River. Volcanic debris, discharged from
a vent into the air, settled as cinders and ash to build
up the symmetrical cone. Pilot Butte has been a state
park since 1927.
Nearby Powell Buttes complex of 11 separate
volcanic domes represents a major silicic volcanic
center that expelled large volumes of lava and ash-flow
tuffs during the Miocene. Domes formed during the
final stages of activity and subsequent erosion produced
remnants known as "hat rocks". Exploratory geothermal
tests have located warm water wells on the north side
of Powell Buttes.
Lava Butte, familiar to anyone who has trav-
elled south of Bend, is a classic basalt cinder cone
projecting 500 feet above the surrounding jagged lava
field. Because it is situated on the flank of Newberry
Crater, Lava Butte is a "parasite cone" and is part of an
almost continuous wide zone of faults and cracks
extending from Newberry Crater to Lava Butte and
beyond. More than 6,000 years ago, lava extruded from
these vents in at least eight separate eruptive events,
flowing northwesterly for 6 miles to dam and divert the
Deschutes River. From the rim of the deep crater, built
