National Parks what the Pumice Desert at Crater Lake is

The sixth oldest park in the United States can be found in southern Oregon. This park is Crater Lake National Park, established in 1902, home to the deepest lake in the United States.

Crater Lake was formed when an ancient volcano erupted; the lake lies in the remains of the volcano’s caldera. The volcano erupted nearly eight thousand years ago to form a nearly symmetrical four thousand feet deep caldera. The mountain was named Mount Mazama and is part of the mountain chain called the Cascade Range, the volcanoes in the range are known as the High Cascades.

Crater Lake is unusual in that it has no streams flowing into or out of it; it has a striking blue tint to it and is re-filled entirely from snow and rain.

Mount Mazama began as an overlapping shield volcano, layers of lava flows alternated with pyroclastic flows until it reached a height of around eleven thousand feet. When Mazama erupted it produced one hundred and fifty times more ash than the eruption of Mount St Helens in 1980. It deposited ash as far east as Yellowstone National Park, as far south as Nevada and as far north as British Columbia.

The ash forms andisol which is a type of soil that has high proportions of glass and amorphous colloidal materials such as allophone, imogolite and ferrihydrite. The soils in Crater Lake National Park are brown sandy loams with large amounts of cobbles, gravels and stones which make their drainage excessive.

The eruption of Mount Mazama gave rise to another unusual feature of the Crater Lake National Park. This can be found in the northern section of the park. Aptly called the Pumice Desert the area was covered with a mixture of pumice and ash to a depth of up to two hundred feet. It covers an area of around five square miles and as the material it is made of is extremely porous it has remained a desert due to organic matter being unable to take hold there.

Very few plants are found in the area although there are a few scattered lodgepole pines encroaching into the edge of the area. As well as the high porosity of the soil in the Pumice Desert it also suffers from a lack of nutrients. The western pocket gopher is also found in the area and it disturbs seeds before they have any chance to become established.

The area is also subject to extreme variations in its climate. Despite all this a variety of plants, around fourteen in total, do survive in the desert, these include the lodgepole pine, some types of grass, various sedges and some flowers. The lodgepole pine (Pinus contorta) grows as a shrub or tree depending on its subspecies. It is one of the first trees to repopulate an area after fire and its wood is often used in the building of the Native American tepee lodge. The lodgepole is long, straight and light making it easier to transport by the nomadic buffalo hunting cultures.

The pocket gopher is a burrowing rodent of the family Geomyidae, small and heavily built with brown fur that blends with their chosen habitat. Their most characteristic features are their large cheek pouches which give them their name. The presence of the gopher is announced by the appearance of mounds of fresh dirt about eight inches in diameter.

The northern entrance to Crater Lake National Park is not far from the Pumice Desert which when viewed from afar is even more stark given that the surrounding area is heavily forested.


Sutton, Ann – Crater Lake National Park: A Global Treasure – Silver River (2002)

Schaffer, Jeffrey – Crater Lake National Park and Vicinity – Wilderness Press (1983)