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Lava Caves Offer (dark) Glimpse into Central Oregon’s Volcanic Past

Arnold Ice Cave near Bend, Oregon
Photo: Brendan Loscar | Arnold Ice Cave near Bend, Oregon

CENTRAL OREGON has been formed and shaped by the fire and molten lava of volcanic activity. This powerful force of nature has made the region a showcase for a variety of volcanic features. The lava tubes in Central Oregon are young according to geologic time. They appear almost as they did thousands of years ago when they were first formed. – From the Guide to Central Oregon Spelunking by David Purcell.

The Central Oregon lava caves are truly a unique geological attraction to our area. While you might read about several more caves in the area, be aware that many are closed year round due to attempt to protect sensitive cave resources.

Here are a few of the lava caves that are open to the public and easily accessible. Remember, be prepared by carrying a lantern or large flashlight and wearing appropriate shoes (the cave floors are rocky and uneven) and dressing for cool temps. It could be 100 degrees outside, but the cave temps remain around 40 degrees.

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LAVA RIVER CAVE

This has long been a popular place along the highway to stop and visit.  At more than a mile long, Lava River Cave is one of the longest lava tubes in the state of Oregon. This is one of the few lava tubes which has an improved trail the whole length of the cave. It enables one to take a leisurely walk underground and view the many geologic features of a lava tube. The Deschutes National Forest maintains visitor facilities at the cave during the summer. Lanterns can be rented for a nominal charge and scheduled tours are given by a naturalist. The facilities and access road are closed during the winter.

 

This was one of the first lava tubes to be discovered by settlers in Central Oregon. Early ranchers often chilled their deer meat inside the cave, which remains about 40° all year. It was first made a park in 1926 to preserve one of the geologic wonders of western America.

The lava tube is several miles south of Bend, on the east side of Highway 97. The highway passes over the lava tube just before the Lava River Cave turnoff. Easy road access, an improved trail and forest service facilities make this an excellent “first cave” to explore.

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Boyd Cave entrance

BOYD CAVE

Located Just SE of Bend off China Hat Road

This cave is located just a few miles southeast of Bend off China Hat Road (also called Forest Road 18 and Arnold Ice Cave Road) within a popular mountain bike trail system called “Horse Butte.” The entrance of this lava tube is a staircase through a small skylight in the ceiling.

The entire ceiling of the lava tube is thin and has cracked in many places. Breakdown of the ceiling and walls covers the floor in some areas. The piles of rock become more difficult to pass as you continue down the tube.

Two large fractures have developed in the tube and through them has washed volcanic sand. The sand has developed into conical piles which lie against the walls. Other sections of the cave floor have not been disturbed since the lava tube was formed. The solidified surface of what was once a river of molten rock has been preserved. Narrow trenches in the floor show where the last streams of molten lava flowed before the entire floor solidified.

About two-thirds of the way down the passageway the tube becomes so narrow that only a crawlway remains. A low rock arch such as this is called a “duckunder.”

Boyd Cave was one of nineteen lava tubes used by NASA to study the formation of lava tubes. Certain surface features of the moon resemble collapsed sections of lava tubes. The lava tubes in Central Oregon were chosen for this study because they are relatively young and unweathered volcanic features.

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Brendan Loscar/Arnold Ice Cave

ARNOLD ICE CAVE

Located just SE of Bend off China Hat Road

This lava tube has a massive flow of ice which cascades down into the cave. A long stairway extends down the steep ice flow but it can no longer be used. The ice level is rapidly rising and has almost covered the stairs. In some places only the top of the hand rail remains exposed. It is safe to enter the lava tube only if a mountain climbing rope is used for a safety line.

Several years ago a second room was present at the end of the cave, but the rising ice has blocked the passageway. When the lava tube was first discovered it was reported to extend for three hundred feet. Now, less than one hundred feet of the cave remains open. If the ice keeps rising it will soon fill the cave.

The ice in this lava tube was used as a source of drinking water by the Indians during the hot and dry summer season. Settlers have also used the resources of the cave. Pieces of ice were cut out and put in watering troughs for range cattle and horses. The town of Bend obtained its ice supply from the frozen lava tube. Ice was usually taken from the Deschutes River but some winters it failed to form. When this occurred, the only ice available was that harvested from ice caves.

The ice inside of the lava tube was cut into large blocks and hauled to the surface by block and tackle. It was then stored in sawdust and taken to Bend by horse and wagon. When electricity and refrigeration came to the area the ice industry faded away since cave ice was no longer needed.

SKELETON CAVE

(open May 1 through September 30 to bouldering outside of gate at cave entrance.)

In 1924, several people from Central Oregon found this lava tube and thought they were the first to discover it. To their surprise, a stick was found inside the cave which had the year 1894 carved on it. Someone had found the lava tube thirty years earlier and left a trace of their discovery.

The lava tube obtained its name because of the numerous bones that were found at the opening of the cave. An abrupt edge encircles the entrance and was a fatal drop for unwary animals. The bones of an extinct bear and horses were found and these have helped to show what type of animals lived in this area thousands of years ago. Intermingled with the relics were the bones of numerous modern animals such as deer, jack rabbit, coyotes, horses, and cows. Some of the bones were found inside the cave and were probably carried there by carnivorous animals. A few of the bones can be found at the lava tube today.

Like most lava tubes, the entrance to Skeleton Cave developed near the head of the tube where the ceiling is the thinnest. The ceiling becomes thicker as the cave progresses to the foot of the lava tube. For hundreds of years volcanic sand has washed into the cave and now covers the first half of the floor. Where the sand ends, a tributary tube joins the main passageway. The small tributary tube was formed by another lava channel which intersected Skeleton Cave. A short way past the tributary tube a section of the cave has a steep downward slope. The passageway at this point is almost circular because most of the lava drained out of this part of the tube.

Info Taken for Educational Purposes From the Guide to Central Oregon Spelunking by David Purcell.

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Visit Central Oregon is the "Official" Tourism Information Resource for Central Oregon, including the communities of Bend, Sunriver, Redmond, Sisters, La Pine, Madras, Prineville, Crooked River Ranch, Terrebonne, Culver, Warm Springs, and Black Butte Ranch.
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