A collapse in the crust of this lava flow reveals a searing hot heart-shaped skylight, a Valentine straight from Mother Earth.
Top image: A skylight in the West Kamokuna lava flow with geoscientist for scale. Credit: Laszlo Kestay/USGS
Lava in Hawaii has just the right viscosity to form enclosed tubes within hardened shells, hidden highways for lava to flow across the landscape. As theUS Geological Survey explains:
Along the same vein, lava tubes are essentially channels that reside underground and also allow lava to move quickly. Tubes form one of two ways. A lava channel can form an arc above it that chills and crystallizes, or an insulated pahoehoe flow can have lava still running through it while outer layers freeze. Lava tubes, by their nature, are buried.
Sometimes the crust collapses, producing a skylight and exposing the lava within. Skylights usually don’t last long as heat lost through the hole is enough to cool the lava, solidifying the flow and infilling the hole. The cooling can even be enough to block the tube entirely, cutting off further flow. Alternately, the collapse can spread, exposing the former tube as a channel open to the surface.