EL PASO
COUNTY NATURAL HAZARDS CLEARINGHOUSE
Unstable Slope Unstable bedrock or surficial deposits on moderate to steep slopes (include Debris Fan, Debris Slide, Landslide, Rock Fall, and Talus).
Debris Fan Deposit of silt, clay, sand, gravel or boulders deposited by debris flows and floods where streams enter larger valleys.
Debris Slide Clay, sand, gravel and boulders that have failed and have moved downslope.
Talus Accumulation of angular blocks of rock at base of cliff or steep slope.
Landslide Blocks of bedrock or surficial deposits failing along a plane of weakness, joints or bedding on moderate to steep slopes.
Rock Fall Area susceptible to falling, rolling or sliding of large bedrock blocks
Floodplain Part of a valley floor over which a river spreads during seasonal or short-term floods. Note that the floodplains and corresponding streams do not always match because the floodplain and streams data were collected at different times, and the path of streams can evolve quickly over short periods of time
Soil Subsidence (related to coal mines) The depression of part of the earth's surface relative to its surroundings resulting from collapsed tunnels and passages in coalfield areas
Swelling soils (shrink/swell soils, expansive soils) Sedimentary clay-shale types that swell or shrink depending on the quantity of absorbed water.
**Note: data for swelling soils are derived from reclassifying a map of soil types (from NRCS's SSURGO database) according to their highest potential for shrink-swell.Dipping bedrock (heaving bedrock) In the Front Range region of Colorado, the normally flat-lying bedrock strata is tilted vertically. Thus, the swelling (expansive) soil layers within the strata are exposed at the surface and cause differential movement, also called "heaving bedrock".