The surface of a river of pahoehoe cools and hardens rapidly as the molten mass of lava beneath continues to flow, causing friction to create its familiar wrinkles.
A toe of molten lava spills out from under the rigid crust of the leading edge of a lobe.
A seemingly static obstruction in a dynamic river of molten lava exists for just a minute before becoming just another bump on the surface of the expansive field of hardened lava along the Kalapana coast.
Lava transforms from pahoehoe to ‘a‘a as it cascades down the face of a sea cliff on the Kalapana coastline, building a new delta of land at its base.
A reverse angle bird's eye view of the same fingers of lava cascading over the sea cliff. Note the transition of the lava from pahoehoe, as it exits the tube near the bottom of the frame, to ‘a‘a, on the new delta of land at the base of the cliff, is caused by degasification and heat loss.