Rhyolite Canyon

This view to the south across Rhyolite Canyon emphasizes the dominance of the hoodoos on the highest peaks of the monument. The highest points are above 7,000 feet (2,100 meters) in elevation.

Print No. A99-71-10

Welded Tuff Hoodoo

Here is a view along the Echo Canyon Trail. Winding between individual hoodoos, one gets the perspective of the size of these tall, narrow monoliths.

Print No. A99-73-6

Here is a close-up of the welded tuff in this photo

Echo Canyon

Looking to the northwest across Echo Canyon. The welded tuff, a devitrified volcanic glass that is extremely hard, keeps the pinnacles from collapsing. It also effectively bounces sound waves. Hence, a shout across the canyon will bounce like a pinball in a pinball machine as it zigzags through the spires. The result when it finally escapes back to the originator, of course, is an echo.

Print No. A99-73-4

Volcanic "Hailstones"

An outcrop along the aptly named Hailstone Trail reveals a white slope full of marble-size spherules. Their size, color, and shape are identical to common hailstones. They even have internal concentric rings, like the coats of ice within a hailstone. These, though, are composed of the same volcanic ash as the material around them. Whether they formed as hailstones do, from condensation during the cooling in the atmosphere due to convection cells (in this case, in a giant volcanic eruption cloud), or form as concretions in the ash long after it has been deposited, is something of a mystery.

Print No. A99-71-12

Here is a close-up of the "hailstones" in this photo

Tree Shadow

Minutes before the sunset, the sheer surfaces of this hoodoo perfectly imprint the shadow of a tree.

Print No. A99-74-7