Although most of the surface of the solidified lava lake is flat, there are a few rough or sloping areas. The sloping areas are caused by settling as the lava cooled and solidified and the influence of the underlying topography. Photo by Steve Mattox, July, 1990.
In some places, as plates of solid lava moved about on the liquid interior of the lake, lava would ooze out along the edges of the plates to form pahoehoe flows. Photo courtesy of the U.S. Geological Survey.
The steep wall below Kilauea Iki Overlook is great for making echoes. The echoes will carry far so a kind word, like aloha, is recommended. The wall also has geologic significance. Geologists dated lava flows above and below a layer of red tephra. Flows above the tephra are 1,000 years old. Flows below the tephra are 1,500 years old. Geologists think that during the 500 years which no lava covered this area all activity was confined to filling a deep caldera at the summit. Photo by Steve Mattox, May, 1995.
North of the trail are a few small steaming areas. A short side trip leads to drill holes and the depths of the lava lake. Be careful, the steam rising from the holes is very hot. Photo by Steve Mattox, July, 1990.
Geologists drilled into the lava lake to study how it cooled and when and in what order minerals crystallized. Photo courtesy of the U.S. Geological Survey.
As the geologists drilled, they recovered cores of solid rock. These rock samples preserve the history of the cooling lake. The magma beneath the crust of the lava lake was liquid at about 2,200 degrees F (1200 degrees C). As it cooled, minerals crystallized in the order olivine, pyroxene, and plagioclase. The lava lakes serve as models to help geologists understand the inaccessible magma chambers that feed volcanoes. Photo courtesy of the U.S. Geological Survey.
Olivine, the first mineral to crystallize, is very common along the trail across the floor of the crater. It is green in color and made of the elements magnesium, iron, silicon, and oxygen. Photo by Steve Mattox, July 1990.
At about 1,800 oF (980oC), magma is completely solidified. At the present time, about 35 years after the eruption, the lava lake is nearly completely solid. The only remaining liquid is along the boundaries between crystals.
Geologists would stand at the edge of the lake to collect lava samples. Photo courtesy of the U.S. Geological Survey, December 11, 1959 (Figure 29 of Richter and others, 1970).
The trail leaves the barren lava and begins to ascend the steep wall of the pit crater. This 300 foot (90 m) climb is in rainforest very similar to the forest along the north rim of the crater.
The trail reaches the crater rim at Thurston Lava Tube. From there it follows the rim back to Kilauea Iki Overlook.
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