Lava tubes are natural caves which form in a most interesting way. Imagine a great volume of lava spewing up from a live volcano and spreading out over the surrounding countryside. At some distance from the volcano, the surface of this thick, red-hot river begins to cool and to harden into rock (basalt).
Underneath the surface, however, the lava is still liquid and as it continues flowing, it leaves a long hollow tube which is often refilled by yet more molten rock from the source volcano. Eventually, the flow stops but the artery through which it ran may remain intact as a cave, sometimes for millions of years.
These caves may occasionally reach great length. The longest in the world is thought to be Undara Lava Tube in Australia (110 kilometers long). Vulcanospeleology is the science which studies lava tubes.
Lava Balls and Lava Falls
A visit to a fairly “young” lava tube (one which is only a few hundred years old) is an amazing experience. Time has literally stood still inside the cave. Lava which was dripping from the ceiling when the cave formed is still in the same place, forever frozen as long, stretched-out, drips. The floor is covered with towers of blobs, and the walls ooze with dribbles.
An excellent example of such a cave is Cueva Iglesia, located 40 kilometers south of Mexico City. Here cave explorers have found forever-frozen lava falls which were once cascades of molten rock and “bathtub rings” on the cave walls, indicating the height of the last flow.
A glance upward reveals a large lava ball stuck to the ceiling. This was originally a boulder floating on a red-hot river of lava. Many of the lava tubes of Mexico, in fact, are not long, straight, subway-like tunnels, as one might expect, but are a confusion of intertwined passageways, somewhat resembling cooked spaghetti.
Bones and Wolves in Saudi Lava Tubes
Some of the oldest lava tubes in the world are in western Saudi Arabia and are thought to be from one to three million years old. Typically, the original floor of these ancient caves is covered with over a meter of dirt in which thousands of animal and human bones can be found.
Saudi Lava tubes also abound in tools and other artifacts from ancient peoples who used the caves as dwellings or for hunting rock doves. Hibashi Lava Tube is unique in its astounding variety of rare cave minerals. Today these caves are home to foxes and wolves which occasionally give explorers a start when they are discovered in the dark.
Formations in Icelandic Lava Tubes
Lava tubes in cold climates have their own special characteristics. The caves of Iceland, for example, not only have dramatic lava stalactites and stalagmites, they also have floors of solid ice, shimmering icicles hanging from the ceilings and even “ice-mites” underneath them.
The Lava Tubes of Mars
It is possible that lava tubes will figure prominently in mankind’s attempts to establish itself on other planets. According to Dr. Penelope Boston of the Caves of Mars Project, the NASA Institute for Advanced Concepts is looking at microrobotic technology that might facilitate access to lava tubes on Mars.
If these Martian caves turn out to be similar to those on earth, it may be possible to seal the entrances and create an earthlike atmosphere beneath the surface of the Red Planet. For future generations, “home sweet home” may be a lava tube.
The Commission on Volcanic Caves has dramatic photos and links to first-hand reports on the exploration of lava caves all over the world.
 |
 |
 |
 |
 |
