Entrance to a lava tube through a collapsed roof, or "skylight".

Lava Beds National Monument preserves an austere yet strangely beautiful expanse of volcanic wilderness, but there is more to this terrain than first meets the eye.

The monument lies on the northern slope of the Medicine Lake volcano. Broad distributions of lava slowly create a large, gently-sloped mountain, known as a shield volcano. The volcano is formed by repeated outpourings of very hot, very fluid lava. At temperatures of nearly 2000 degrees Fahrenheit, these flows can travel great distances.

During an eruption, lava courses down the mountainside, but soon begins to cool. Rivers of flowing lava crust over, in much the same way as a river of water freezes over during a cold winter. The crust insulates the lava beneath, keeping it hot and fluid. Eventually the eruption stops, and the lava drains away, leaving a hollow tube within the hardened lava flow.

As the lava cools it shrinks and fractures, forming anything from small skylights to large pits and trenches. These collapses allow us entry into the world of lava tube caves. Once inside the caves, we can witness the evidence of lava having flowed through the tube.

Walls and ceilings are covered with dripstone and lavacicles, formed as lava dripped from above and cooled. Flow lines and benches mark the various levels of lava flows inside the passage. The floors of the caves, when not covered by collapse blocks, reveal the wrinkled surface of the last surges of lava.

Some underground features originated long after the tubes cooled to their present temperatures. Just as limestone caves contain spectacular formations of minerals deposited by water, lava tube caves contain cave coral. This extremely delicate feature is formed as water, seeping through cracks into the cave, evaporates and deposits minerals which crystallize into intricate shapes.

Temperatures in most caves average 52-55 degrees Fahrenheit, the annual average temperature of the surface. A few caves maintain temperatures of 32 degrees which freezes any water that seeps into them. When entering any of the ice caves, be prepared for cold temperatures, even in summer.

Native Americans of the Tulelake Basin knew of the caves long before modern-day immigrants moved into this area. Evidence of this is found in the many examples of rock art painted in or near cave entrances. These pictographs, as well as any other artifacts found here, are priceless, irreplaceable relics of this region's ancient culture. If you find any archaeological evidence, please do not pick it up or disturb it in any way. Report your discovery here at the visitor center.

When entering a cave, you will notice plants that grow in the cool, damp transition zone between the desert climate outside the cave and the darkness of the cave's interior. Mosses, mushrooms, and even ferns are adapted to grow at cave entrances. Please be careful not to trample them, as their footholds are quite delicate. Also at cave entrances you may first come in contact with some of the wildlife associated with the caves.

Snakes, including the poisonous western rattlesnake, are commonly found in warmer months resting in the shade and cooler temperatures found near the entrances. To be safe, avoid placing your hands or feet where you can't see them, particularly in shady areas under rocks and bushes.

One interesting form of life inside the caves doesn't look much like other forms of life you've ever seen. Thin, fragile coatings of cave slime cover many of the cave walls. These colorful patches are colonies of bacteria which are hydrophobic. Repelled by the bacteria, water beads up and glitters in the light of your lanterns suggesting cave names like Golden Dome.

More obvious evidence of life in the caves are the nests built by woodrats, packrats of western literature. These piles of twigs, small rocks, litter, and droppings are frequently seen perched atop ledges or large boulders, and provide shelter for the woodrats. However, they may also harbor the woodrats' fleas which frequently carry bacteria that can transmit bubonic plague, as well as other dangerous diseases. Please stay clear of any area resembling a rat nest.

The caves of Lava Beds are also home to many species of bats. During the warmer months, bats are active from dusk to dawn, feeding on flying insects. In summer, pregnant bats cluster on cave ceilings, forming maternity colonies. Approaching or disturbing these colonies endangers the lives of the newborn bats by causing the mothers to take flight. In doing so, the commotion may cause young bats to lose their grip and fall to their deaths.

In winter, many bats hibernate in the caves. Their hearts beat very slowly, and their body temperatures drop. This allows them to survive long, cold winters without eating. Awakening the bats during their deep sleep forces them to use up their energy reserves. When this happens, the bats may starve before the warm season brings more insects for them to eat.

One bat you may see at Lava Beds, the Townsend's big-eared bat, is a candidate for the federal threatened species list. To protect these bats, please obey any signs closing caves for either winter hibernation sites or summer maternity colonies.

When exploring one of the many lava tube caves, remember these simple rules to make your visit much more safe and enjoyable. Make sure each person in your group is carrying a strong, reliable source of light. If you plan to be underground for more than just a short time, carry at least two additional emergency sources of light per person. Flashlights are checked out here at the visitor center at no charge.

You may use your own sources of light in the caves as long as they are battery-powered. Gas lanterns or carbide lamps are prohibited, as they produce heat and fumes which are harmful to the caves' environment. Also, please don't smoke in the caves.

Protect your head from low ceilings by wearing a hat, preferably a bump hat (for sale at the visitor center), a hard hat, or a bicycle helmet. Wear sturdy footwear, as cave floors are rocky and uneven. Knee pads and durable gloves are also recommended when exploring a cave where crawling or climbing may be involved.

Watch out for unstable rocks and ledges or dropoffs. Please stay on an established trail if one exists. We do not recommend exploring caves by yourself. If you do go alone, carry at least three sources of light and tell someone at the visitor center where you are going and when you plan to return.

Do not bring food or beverages into the caves, and please carry out all litter. Also, please use the restroom before entering the caves. Caves must not be used for this purpose. Pets are not allowed in any cave for this reason, as well as for your pet's safety.

Take care to avoid wildlife living in and around caves, such as rattlesnakes, rats, and bats. This is for their protection and for your safety. And please, resist the temptation to touch the fragile features of the caves. If damaged or vandalized, the ice in the ice caves, or any patches of cave slime, will take years to heal. The delicate cave corals have taken many thousands of years to grow to their present size. And lava formations such as lavacicles or the rare lava helictites will never grow back once broken.

Enter the caves, understanding the amazing processes that created them, but realize that they are now the homes of certain animals and plants. One day, a new lava flow may bury these caves and create new ones. Until then, please treat the caves with respect, leaving them as clean and undamaged as you would wish to find them. Only then will others truly appreciate the caves for the wondrous places that they are.

Further information: Caving at Lava Beds »