The Coconino National Forest in northern Arizona contains a volcanic field that has been reshaping the landscape for the past six million years. Although there are no active volcanoes in the area, remnants of past eruptions can be seen in the form of igneous basalt rocks and lava tubes. The volcanic field created a mountain range that stretches for 50 miles from Williams to Flagstaff. The eruptions that occurred around 700,000 years ago were similar to those that created the Hawaiian islands, with low viscosity lava flowing downhill like a river of water. As the molten lava encountered atmospheric pressures and temperatures, it cooled down rapidly and created a new ground level. Lichen, a combination of algae and fungus, can be seen growing on the basalt rocks. Lava tubes were created as the lava flowed through and drained out hollow tubes underground, leaving behind multiple chambers. The stalactites in the lava tubes are not the result of calcium buildup, but rather of superheated rock that liquefied and melted.