• View of Grand Canyon National Park at sunset from the South Rim

    Grand Canyon

    National Park Arizona

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  • Expect Isolated Thunderstorm Activity Through Thursday. A Greater Chance on the Weekend

    Monsoonal weather patterns have moved into the Grand Canyon area decreasing fire danger. As a result, on Tuesday, July 8 at 8 a.m. fire managers lifted fire restrictions within Grand Canyon National Park. More »

  • Two Bats Collected in the Park Have Tested Positive for Rabies

    One on the North Kaibab Trail and the other at Tusayan Ruin/Museum. Any persons having physical contact with bats in Grand Canyon National Park, please call 928-638-7779. Rabies can be prevented if appropriate medical care is given following an exposure. More »

Biological Soil Crusts

Cryptogamic crusts, N. Herbert NPS

Cryptogamic crusts

NPS Photo by N. Herbert

Biological crusts (also known as cryptogamic, microbiotic, crytobiotic and microphytic crusts) are microscopic non-vascular assemblages composed of blue-green algae, diatoms, golden brown algae, lichens, mosses and a few xerophytic (adapted for growth with a limited water supply) liverworts on more mesic (moderate amount of moisture) sites.
 
Don't bust the cryptogamic crust logo
Blue-green algae contribute to the bulk of the algal tissue. Biological crusts grow on and within soils and other substrates, modifying these surfaces in significant ways. The blue-green algae fix atmospheric nitrogen and thus enhance the nutrient status of the soil.

Cryptogamic crusts retard erosion by wind and water, help retain soil moisture during dry periods, slow evaporation rates, and enhance seedling establishment. These living crusts are extremely fragile and one footprint can set back development for decades.

For more information on Biological Soil Crusts visit this USGS Soilcrust website.

Did You Know?

UNKAR DELTA IN GRAND CANYON

At the bottom, where Unkar Creek joins the Colorado River sits Unkar Delta where prehistoric Pueblo people occupied numerous sites here for about 350 years (A.D. 850 to A.D. 1200)