Geology Reference
In-Depth Information
Newberry Volcano monument, covering 62,000 acres
south of Bend, provides a panorama of forests, lava
flows, volcanic cones, lakes, and craters.
craters, and other features on the flanks occur in zones
ing of Glass Butte, Little Glass Butte, eastern Glass
radial to the caldera. Basalt flows, forming most of the
Buttes, and Round Top Butte .The low domes aligned
north and south flanks, are younger than the ash flows
in a west-northwest direction for about 12 miles built
of the east and west flank which are covered by a thin
up in a long eruptive process which may have taken as
veneer of ash. Paulina Creek drains the caldera,
much as 1 million years to complete. The Glass Buttes
dropping over the west rim as Paulina Falls to flow
group produced significant amounts of obsidian which
westward into the Deschutes River.
was gathered by Indians in prehistoric times and more
Over the past decade Newberry Volcano has been
recently by rock collectors. Besides the common black
the site of intensive investigation for its geothermal
obsidian, there are mixtures of red and black as well as
potential, and drilling has encountered an active
iridescent silver obsidian. Obsidian or volcanic glass
hydrothermal system beneath the caldera. The recogni-
has no internal crystalline structure. The failure to
tion of the delicate ecological balance here should
form crystals may be due to the exceedingly high
eliminate any future exploitation at this site.
viscosity prior to cooling. Very small amounts of
Glass Buttes east of Newberry Caldera is a 5
quicksilver have been mined from the volcanics of
million year old silica-rhyolite volcanic center consist-
Glass Buttes.
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