This is the fifth in a series of eight earthcaches being
developed at major points of interest in Newberry
National Volcanic Monument in cooperation with the staff of the
Deschutes National Forest. Lava River Cave is closed to all entry
from November 1 to April 30 to protect hibernating bats. For the
remainder of the year (May 1 to October 31) the cave is open to the
public. The cave entrance is staffed from approximately Memorial
Day to Labor Day. No logs for this earthcache will be accepted
from November 1 to April 30.
To log this cache you will need to go more than half way through
the cave and you will need a tape measure. Please post a photo
taken in the cave. There are three interpretive signs in the cave,
e-mail me the "sign titles" and "width of the cave" at each of the
signs (to the nearest foot).
While doing this earthcache you may also be able to collect the
necessary information to claim several waymarks in the area.
Lava River Cave is an excellent example of a lava
tube and is the longest continuous tube in Oregon.
During long-lived eruptions flowing lava becomes
channelized into a few main streams. Overflows of lava from these
streams solidify quickly and plaster on to the channel walls,
building natural walls that allow the level of the lava to be
raised. Lava streams that flow steadily in a confined channel for
many hours to days may develop a solid crust or roof and thus
change gradually into streams within lava tubes. If molten rock
(magma) stops rising to the surface at the source, the still-molten
lava moving beneath the crusted-over top of a lava flow can
continue to drain downhill and may ultimately leave an open lava
tube cave. Because the walls and roofs of such tubes are good
thermal insulators, lava flowing through them can remain hot and
fluid much longer than surface flows. Tube-fed lava can be
transported for great distances from the eruption sites.
Newberry Volcano has been the source of numerous high volume
tube-fed lava flows that have flowed northward well beyond Bend.
These high volume flows generally come from small spatter/fissure
vents. These vents were typically low on the flanks of Newberry.
The highest elevation vent was in the area of Mokst Butte but it
has been buried by Mokst Butte and its flows. The eruption from
this vent occurred about 80,000 years ago and resulted in a flow
which nearly reaches Redmond and underlies much of Bend. Lava River
Cave was a major tube that carried the flow westward to the
Deschutes River.
