Geology Picture of the Day – Pahoehoe
A type of lava formed from very fluid basaltic flows is called pahoehoe. In today’s geology picture of the day, we see a beautiful example of ropey pahoehoe from Hawaii Volcanoes National Park.
Image Credit: bgustus2000 on flickr.
For more information on the types of lava, visit Instant Hawaii.
One of the more interesting types of pahoehoe lava is called ropey pahoehoe and looks like a series of twisted ropes spaced evenly along the ground. The twisted ropes may be fairly straight, or may loop and wind in and out much like a fingerprint. Many visitors express interest in what could create such an unusual shape, but once you see ropey pohoehoe lava being created it is instantly clear how the shapes occur. As the pahoehoe flows, it usually encounters some minor barrier that slows up the front of the flow. As the front of the flow is slowing down, the faster flow behind it pushes the front and forces it to create a small ridge, which it pushes up and over the barrier. That ridge begins to cool and creates the next barrier, which in turn creates the next. The result is a series of ridges interspaced with valleys – which looks like 4 inch thick ropes of lava laying side by side or looping side by side. To walk over ropey pahoehoe it is best to walk on the top of the ridges, perpendicular to the ridges.
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