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Pahoehoe
Picture left - Toes of a pahoehoe flow advance across a road in Kalapana on the east rift zone of Kilauea Volcano, Hawai`i.Pahoehoe is a Hawaiian term for basaltic lava that has a smooth, hummocky, or ropy surface. A pahoehoe flow typically advances as a series of small lobes and toes that continually break out from a cooled crust. The surface texture of pahoehoe flows varies widely, displaying all kinds of bizarre shapes often referred to as lava sculpture (see pahoehoe terms below). |
 Close view of ropy texture forming on the surface of a pahoehoe flow at Kilauea Volcano, Hawaii. |
Ropy pahoehoe
Ropy pahoehoe is the most common surface texture of pahoehoe flows. The numerous folds and wrinkles ("ropes") that are characteristic of ropy pahoehoe form when the thin, partially solidified crust of a flow is slowed or halted (for example, if the crust encounters an obstruction or slower-moving crust). Because lava beneath the crust continues to move forward, it tends to drag the crust along. The crust then behaves like an accordian that is squeezed together--the crust is flexible enough to develop wrinkles or a series of small ridges and troughs as it is compressed and driven forward. |
 Person sitting on entrail pahoehoe along the Chain of Craters Road in Hawaii Volcanoes National Park, Kilauea Volcano, Hawaii. |
Pahoehoe entrail Named after the texture of an animal's intestines entrail pahoehoe best forms when pahoehoe flows down a steep slope. It is usually found on the sides of rootless vents, such as hornitos and ruptured tumuli. On the south flank of Kilauea the most striking examples occur where pahoehoe oozed down steep scarps in the Hilina fault system. |
 These small glowing pahoehoe toes were fed by lava that broke out from a lava tube (out of view) at Kilauea Volcano, Hawaii. |
Pahoehoe toe Small protuberances called "toes" are common along the edges and flow front of an active pahoehoe flow moving across flat or gentle slopes. The flow spreads as the small toes grow in size and merge together to form a broader front, which in turn inflates with new lava moving through the molten core of the flow. Another series of budding toes will break out, move forward, and start the process over again. |
 Lava coil on pahoehoe flow, Kilauea Volcano, Hawaii. |
Pahoehoe Lava Coil Lava coils are spiral or scroll-shaped features that form along slow-moving shear zones in a flow; for example, along the margins of a small channel. The direction of flow can be determined from a lava coil. Lava on the right side of the photo was moving toward the top of the view relative to lava on the left side. |
 Blister on the surface of a pahoehoe flow, Kilauea Volcano, Hawaii. Note U.S. quarter for scale. |
Pahoehoe blister Blisters are thin-walled basaltic-glass bubbles formed by the release of volcanic gas from the surface of a pahoehoe flow. Like a glass blower that blows air into molten glass to create a goblet or vase, gas released from lava may force the thin glassy crust of a lava flow to form a large bubble or blister. They are found on all types of pahoehoe flows. |