Lava Channels
Lava sometimes forms a tube as it moves away from the vent (opening from which lava flows from a volcano). The top of a stream of lava cools down, thereby forming a solid roof. Meanwhile, the lava continues moving in the tube. Often, when all the lava leaves the tube, the roof collapses, making a channel. These features are found on Mars. Some can be seen around Pavonis Mons, in the picture below. Some people have suggested that future colonists on Mars could use lava tunnels as shelters. They would offer great protection from radiation, especially ultraviolet radiation. Lava Channels on the flank of the volcano Pavonis Mons are pictured below in a picture from Mars Odyssey THEMIS. Sometimes the lava tube remains intact for a time. Lava will break out along the tube to accumulate or flow away. Lava flows often have a lobate appearance at the edges. A good view of such a lava tube is shown below.
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Lava tubes were once covered over with lava flowing in them, but the roofs have now collapsed and the lava has left. Also, some straight troughs (grabens) crosscut the lava channels. Picture taken by THEMIS.
Read more about this topic: Phoenicis Lacus Quadrangle
Famous quotes containing the words lava and/or channels:
“We walk on molten lava on which the claw of a fly or the fall of a hair makes its impression, which being received, the mass hardens to flint and retains every impression forevermore.”
—Ralph Waldo Emerson (1803–1882)
“It is worth the while to detect new faculties in man,—he is so much the more divine; and anything that fairly excites our admiration expands us. The Indian, who can find his way so wonderfully in the woods, possesses an intelligence which the white man does not,—and it increases my own capacity, as well as faith, to observe it. I rejoice to find that intelligence flows in other channels than I knew. It redeems for me portions of what seemed brutish before.”
—Henry David Thoreau (1817–1862)