Massive Newberry shield volcano covers an area of about 1600 sq km about 60 km east of the crest of the Cascade Range in central Oregon. The elongated, low-angle shield volcano covers an area of 60 km in a N-S direction and 30 km E-W. More than 400 cinder cones dot the flanks of Newberry volcano, including Lava Butte cinder cone at the left center of this photo, one of many cones formed around 6100 years ago along the NW rift zone.
Glassy black obsidian is prominent in the Big Obsidian Flow erupted from Newberry caldera in central Oregon. The high-silica rhyolitic flow covers 20 sq km of the caldera floor. Obsidian flows are never entirely glassy, but also contain large amounts of frothy pumiceous material and devitrified spherulites, which commonly form bands alternating with layers of glass.
Some the more than 400 cinder cones that dot the flanks of the massive 30 x 60 km wide Newberry shield volcano in Oregon are seen in this view from Paulina Peak on the south rim of Newberry caldera. The cinder cones at Newberry are most abundant on the north and south flanks. Many are of Pleistocene age, but cinder cones along a rift on the NW flank and some on the south flank have erupted during the Holocene.