The pumice deposits you are now standing
on are the product of Mt. Mazama, an
explosive volcano that collapsed to form the
Crater Lake caldera. Mazama stood about 6
miles (9.7km) south of here (to your left).
About 7,700 years ago Mt. Mazama erupted
torrents of seething, red-hot pumice and other
volcanic rocks. These glowing avalanches raced
down the slopes and flooded the valley that lay
here with deposits over 100 feet (30m) deep.
Even after thousands of years, few trees have
become established on the Pumice Desert.
There is ample water under the surface, but
deficiencies in the soil limit plant growth. Many
more years will pass before the surrounding
logdepole pines transform the desert to a forest.
Pumice Desert is composed chiefly
of pumice and scoria ejected by Mt.
Mazama. Pumice is light-colored,
porous, and extremely lightiweight.
Scoria is often reddish, and noticeably
darker and heavier.