PDS_VERSION_ID        = PDS3
RECORD_TYPE           = STREAM

OBJECT                = TEXT
  PUBLICATION_DATE    = 2009-11-15
  NOTE                = "Geologic setting description"
END_OBJECT            = TEXT
END

Lava Butte

Lava Butte is a cinder cone that is part of a system of small cinder cones
that lie on the northwest flank of Newberry Volcano, a basaltic shield volcano
in central Oregon. Lava Butte is 150 m tall, with a central crater that ranges
from 20-50 m deep, and its formation can be dated to about 7,000 years ago.

The eruption that formed Lava Butte began as a fissure eruption of gas-charged
basaltic andesite. After a short initial period of fire foutaining along this
2.4 km- long fissure, the eruption concentrated in the Lava Butte area. The
accompanying decrease in fluidity meant that the escaping gases carried with
them larger quantities of foamy, fragmented lava (cinders). These fell back to
form the Lava Butte cinder cone. The cone's higher north rim is a result of
the prevailing winds.

During the eruption, lava broke through the thinner south side of the
structure and spread to the north and west. Only 9% of the eruptive volume is
in the cinder cone itself; 90% is contained in lava flows that covered over 23
square km and buried the old channel of the Deschutes River with over 30 m of
lava. This dam resulted in Lake Benham, which found an outlet in a new channel
that extends from Benham Falls to Dillon Falls at the present time.