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| Cascades Volcano Observatory, Vancouver, Washington |
| Visit A Volcano |
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| Mount Tabor Cinder Cone and the Boring Lava Field |
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Mount Tabor, located east of Portland, Oregon, is a Plio-Pleistocene cinder cone of the Boring Lavas.
The Boring Lava field includes at least 32 and possibly 50 cinder cones and small shield volcanoes.
The best and most accessible exposure is the cross-section of the
cinder cone in Mount Tabor Park at about 64th St. between Hawthorne and
Stark Avenues.
Numerous quartzite-pebble xenoliths from the underlying Mio-Pliocene
Troutdale gravels which make up the bulk of Mount Tabor have been found
in the cinders here
From: John Allen, 1990, IN: Wood and Kienle, and John Allen, 1975. |
| From Mount Tabor Parking Lot |
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A parital cross section of the Mount Tabor cone
of olivine basalt is exposed beside the basketball court and outdoor theater.
Some of the cinder beds contain very large ejecta (more than 1 meter in long
dimension), whereas other beds, especially high in the section, are relatively
fine grained and well sorted. The general dip is northwestward, away from the
breached crater that the road traverses. Several fault surfaces suggest
slumping of the flank of the cone during its formation. Gravel in some of the
younger beds in the middle of the exposure were probably derived from the
underlying Troutdale Formation (Trimble, 1963), and the younger beds at the
north end of the exposure are partly palagonitized. This evidence suggests
interaction with water.
From: Swanson, et.al., 1989, IGC Field Trip T106: Cenozoic Volcanism in the Cascade Range and Columbia Plateau, Southern Washington and Northernmost Oregon: American Geophysical Union Field Trip Guidebook T106. |
| Mount Tabor Park |
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They don't call Mount Tabor a mountain
for nothing. This park is actually an
extinct volcanic cinder cone, a small
mountain in the city. Miles of trails and
roadways wind through tall trees and
well-maintained landscape, and most
lead to the top, a trip rewarded by
breathtaking views of downtown and the
West Hills from one side, Mount Hood
and the outer Eastside from the other.
Mount Tabor is filled with joggers and
bikers building up their endurance on
either the steep roadway or steps. In
addition, there are tennis courts on the
west and northeast sides of Tabor and
basketball courts on top.
With its views of Portland, barbecue
facilities and shady areas, Mount Tabor
makes a great picnic location.
-- Information courtesy Jenny Tom,
"Portland City-Search" Website, January 2001
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