The brilliant morning sun reaches across the high desert; the air is so cold, hoar frost stands straight up off the ground. It decorates the branches of sagebrush, nearby bunchgrass and is also the only thing that leaves any evidence of my path. Cinching the chinstrap on my climbing helmet, I step onto an icy vertical ladder in order to descend below the surface. Moving methodically down through the opening of the cave, I can feel the updraft of warm moist air moving past me. Reaching the bottom of the ladder, stepping off, and taking a few steps from the landing into the deep darkness of what lies below, I press the button on my headlamp—the closed in world illuminates in the focus of my light and I know I have arrived into a completely different world.
Lava Beds National Monument, located in California and near the Oregon border, features more than 700 lava tube caves. These renown geological formations, make up the most concentrated area of lava tube caves within the continential United States. Not only are the caves spectacular on their own, they have grown to support a remarkable array of delicate cave life.
When the Mammoth Crater erupted spilling lava, it formed a connection of lava tubes from higher elevations towards the valley, known as Tule Lake. The transformative past of this landscape is revealed not only by the crater, but also by Medicine Lake volcano with whom the crater is associated. Now, frozen in time, the lava flows can still be seen on the landscape, cinder cones reach skyward, and sleepy volcanoes in the southern reaches of the Cascade range, with their snow capped summits, can be seen in the distance—including Mount Shasta.
Below the surface, the intricate details of a time marked by molten lava are revealed. Here, the story is not weathered; it comes to life with each measured step, in a geological account turned to stone. With the turn of your headlamp, you can begin to “read” the walls, floors, and ceilings to understand the past. Looking closely, the lava tubes become distinctly individual, revealing how the lava flowed in them. In some caves the molten flow cooled, its’ “ropy” character a distinct feature termed pahoehoe (pa-hoi-hoi). In other areas the rock is blocky and rough, termed A’a (ah-ah) and formed by hardened rocky material that was floated or transported on top of molten lava. In some caves, the ceilings have lavacicles (lava that cooled while dripping) while others feature ice stalagmites reaching upwards from the ground or ice floors, revealing the presence of water.
Taken together, the caves feature amazing structural diversity—adding the presence of water, ice, and airflow provides a new level of uniqueness—climate. Each cave, along with its geological features is unique in the climate and habitat it supports—some are warm and humid while others are cold and may even contain ice formations lasting throughout the year.
The caves and their unique climates provide a remarkable array of habitats for flora and fauna adapted to cave life. Many caves have collapsed sections, which provide plants and animals entry into the caves. Whether entering from a cave opening or via a collapse area, the caves feature transition zones, which influence the habitat found there; these can be divided into four zones: the entrance zone, twilight zone, transition zone and dark zone. The entrance zone can be influenced by conditions outside of the cave; the twilight zone is marked by a decrease in light; while the transition zone may be influenced by air and moisture even though it is in darkness; and the dark zone remains in darkness and is essentially stable.
Remarkably, a variety of species utilize the habitats associated with the caves and these zones, from specialized bacteria to plants, birds, insects, frogs, kangaroo and wood rats, and yes, even pika! In fact, Lava Beds features what is considered a low elevation population of pika, and this is due to the geology of the area and presence of cooler habitat associated with caves and talus-like formations. Another highlight of the caves, is the presence of fourteen different species of bats, all of which are insectivores, including the Townsend’s Big-eared bat (Corynorhinus townsendii).
During the warmer seasons of spring and summer, some species of bats will inhabit the caves and set up maternal colonies in order to birth and care for their young, known as pups. The bat pups are completely dependent upon their mothers until they successfully develop the ability to fly and are able to feed and care for themselves. During the cooler months of fall and winter, some bats will leave the area for warmer climes while others will find suitable caves or other locations for hibernating. During this time, as with the maternal colonies, bats are sensitive to disturbance and many of the caves close to visitors in order to respect and protect the bats inhabiting these locations.
Along with remarkable biodiversity, the caves also hold a deep and powerful connection for people—in fact, many of the caves feature pictographs and petroglyphs. These caves play a key role in the culture of the Modoc people and their ancestors, with generations of inscriptions in place for all to celebrate and wonder at. In addition, settlers to the area created a connection to the caves, exploring, mapping and celebrating the landscape. Taken together, the geology, biodiversity and human connection to place led to Lava Beds becoming a national monument in 1925. Today, it remains protected and accessible for people to enjoy.
On a personal note, I have no doubt that this underground labyrinth has the power to enchant the explorer in all of us—to fill us with wonder and excitement about our geologic past and the species that call this place home. It can inspire us to learn more about it, protect it and share it. Never before have I visited a place that has so captured my spirit of discovery— it has left me asking question after question—and hungry to find answers.
It leaves me wondering—who knows what more we will find in the darkness, who knows what we can discover next?
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Photo credits: Shauna Potocky