Geology Reference
In-Depth Information
matic intrusions bowed the ground surface into several
low rounded domes. One of the eruptions produced
spherical-shaped volcanic bombs along with flows of
pahoehoe lava that created deep fissures and ridges.
These bombs ranging from the size of a pea up to 2
feet in diameter were ejected as air borne blobs of
liquid lava that cooled and cracked in flight. A more
dramatic result of these volcanic events is the large
depression or Graben Dome, 7,000 feet long, 1,250 feet
wide, and 100 feet deep that developed as lava drained
away underground causing the upper surface of the
crater to collapse and create a basin.
Volcanic Buttes, Lava Cast Forest, Newberry Crater
Cinder and basalt cones stand out on the flat
landscape near Bend and along the route from Bend to
Burns. The most notable of these are Pilot Butte just
east of the Bend city limits, Powell Buttes to the
northeast, Newberry Crater and Lava Butte to the
south, and Glass Buttes to the east.
Pilot Butte, a prominent feature in central
Oregon, served as a landmark for pioneers travelling to
the Willamette Valley. A view atop the lone cinder
cone, 4,136 feet above sea level and 500 feet above the
The central crater complex about one mile in
diameter is a moonscape of overlapping volcanic
features (photo courtesy Oregon Dept. Geology
and Mineral Industries).
Diamond Craters Lava Field
south of Malheur Lake exhibits
a wide variety of volcanic
features.
