Fluted lava, Grand Canyon
This lava boulder lies on the right bank of the Colorado River just above Lava Falls, along the trail the river guides use to scout the rapid. The lava is about 1 million years old. The river has polished and scooped out intricate patterns in the lava surface. Lightest areas are reflections of the sun from the shiny rock. Sculpting likely occurred during high-water episodes, with the river carrying a huge load of sediment. This would act as an abrasive and help scour out the rock. These huge flows have ceased since the gates of Glen Canyon Dam closed in 1963.
Fluted lava, Grand Canyon
This lava boulder lies on the right bank of the Colorado River just above Lava Falls, along the trail the river guides use to scout the rapid. The lava is about 1 million years old. The river has polished and scooped out intricate patterns in the lava surface. Lightest areas are reflections of the sun from the shiny rock. Sculpting likely occurred during high-water episodes, with the river carrying a huge load of sediment. This would act as an abrasive and help scour out the rock. These huge flows have ceased since the gates of Glen Canyon Dam closed in 1963.