Lava
Tube Caves
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| Ladder leading into one of the lava tube caves at Lava Beds. |
Lava tubes generally occur when an
eruption of very fluid lava occurs on a sloped landscape where the lava is able
to flow continuously downhill. As the lava flows down the slope, the exposed
lava begins to harden and form a hard outer shell. This shell then insulates
the lava that is still flowing hot inside of the casing causing it to continue
flowing through the tube until it reaches the end where it either drains out or
seals at the end of the tube.
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| Ferns and moss growing inside of the lava tube caves at Lava Beds. |
As a result of weathering and gravity, the tubes
at Lava Beds National Monument have some areas where the ceilings are collapsed
or they have been punctured. This allows visitors to actually go inside of the
lava tubes and explore the unique composition inside of these lava caves.
Additionally, these openings provide a place for wildlife and foliage to enter
the caves and thrive in this unique habitat. The caves at Lava Beds are home to
an array of wildlife including threatened bats and bacteria, tree frogs, and
sword ferns. Today there are over 700 individual caves for visitors and
wildlife to enjoy at the Lava Beds.
Cinder
Cones
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| Perfectly shaped cinder cone in the northern portion of Lava Beds. |
Cinder cones can be found all around the
Lava Beds landscape. These unique formations were formed when the dissolved gases
contained within magma are placed under high pressure and cause an eruption that
blows a spout of lava into the air. The cooling lava then falls into what is
known as cinders around the eruption site. Many of these cones may ooze lava
from their base if the eruption’s underground magma source changes character
such as the Schochin Lava Flow that emanates from Schonchin Butte. This cinder
cone at Lava Beds offers visitors a trail that they can follow to the top of
the cone.
Spatter
Cones
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| Spatter cone at Lava Beds. |
Lava Beds is also home to a number of
spatter cones. These occur when thick clumps of lava are thrown from a vent.
These clumps do not go quite as high into the air as the eruptions that form
cinder cones. These clumps form cones where they land that can sometimes create
formations similar to a hollow chimney. Fleener Chimney at Lava Beds has great
examples of just how large these spatter cones can be with some of the cones
measuring 150 feet deep.
Crater
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| Mammoth Crater at Lava Beds |
One feature at Lava Beds is called
Mammoth Crater. As one might guess, this feature is a massive indention in the
earth’s crust among the lava flows at Lava Beds. The crater was formed when a
large lake of lava overflowed rather than erupted and emptied the pit, leaving
behind an enormous crater. The fluid, basaltic lava that once sat in the pit
flowed for miles into the northern portion of Lava Beds. These flows formed
lava tubes all along their path from Mammoth Crater to the northern end of the
park.
Fault
Scarps
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| Fault Scarps at Gillem Bluff in Lava Beds |
Fault scarps occur when a large portion
of crust moves relative to other portions of crust. This can occur for a number
of reasons including violent earthquakes. When this movement occurs, long
cliffs or ridges form along the fault. Gillem Bluff in Lava Beds is a great
example of this type of plate activity. Tectonic plate movement in this portion
of the park has left layers of ancient basalt exposed. The basaltic rock is
believed to be around two million years old.
