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Winter 2010

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

January 12, 2010

Frost heaves: Ice raises the ground


Weather conditions have been favorable for the formation of frost heaves: Heavy rainfall and melting snow from the last week of December, followed by a long bout of freezing weather, created dynamic subsurface freezing that lifted some exposed soils up onto a bed of sharp ice crystals. (Looks spongy; feels crunchy underfoot.)

Frost heaves can damage soil structures, making soils more prone to erosion. Heaves can also lift overwintering plants out of the ground, breaking roots and exposing the roots to freezing temperatures. Heaves can also shift, and possibly damage, fence posts, sidewalks or other structures set into the top couple of feet of earth.

SOURCES: USDA; "Development of a Frost Heave Test Apparatus," by Russell D. Lay; D.C. Department of Consumer and Regulatory Affairs

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