1. Principles of Erosion and Deposition

    Moving water carries soil particles and rock fragments (sediments)

    • As water moves faster it carries more sediment and larger particles.

    • As water slows down larger particles are deposited first. This causes sorting of particles to occur. Rivers move fastest and carry the most sediment during flooding

    1. Material worked and deposited by fresh water

      1. Alluvial Fans

        1. formed where stream gradients decrease quickly sediments fall out

        2. very common in mountain regions

        3. common in arid and semi-arid regions

        4. usually coarse textured generally well drained

      2. Floodplains and Terraces

        1. terraces represent remnants of older floodplains -river has downcut to a new floodplain leaving the older floodplain as a terrace

        2. soils on a floodplain are:

          relatively young-contain stratified material -generally very fertile -sediment deposited (often topsoil eroding from nearby or upstream)-on a world wide basis are some of the most important agricultural soils; these were the first soils farmed by man-are poor sites for intensive urban development

      3. Deltas

        1. formed when finer sediments carried by rivers are deposited into a large body of water (lake or ocean)-fertile soils but very wet-Mississippi and Nile river have two of the largest and most well known deltas.

        2. Soils formed on deltas are very wet, silty and clayey, very fertile-collect topsoil and chemicals from areas upstream.
  2. Marine Deposits

    1. Beach or shore deposit; sandy soils

      very little clay and organic matter

    2. Deep Water (off shore); salt water clayey soils

      These parent materials are usually already highly weathered before the soil formation processes start. The material has been weathered from the original rock, weathered and worked over in the river and stream systems,

      • quartz is usually the dominant mineral

      • Coastal plain soils are well developed.

      • generally have thick E and B horizons

  3. Glacial Deposits

    1. Glaciers form when:

      1. Annual snowfall is greater than snow melt

      2. Snow accumulates; it compresses into ice and begins to flow

    2. Glaciers carry material as they flow

      1. Glacial Till

        1. unconsolidated deposit containing any proportion of gravels, sands, clay, boulders.
        2. material deposited directly by the ice
      2. Glacial Outwash
        1. stratified deposits formed from meltwater

        2. large flushes of meltwater in the summer allowed for the deposition of fairly large rocks and boulders

        3. course, gravelly, sandy, stratified

  4. Wind Deposits

    Eolian Deposits

    1. Loess (pronounced) "luss"

      1. silt-sized particles deposited by wind

      2. in U,S, loess originated from dry floodplains of glacial streams

      3. Rock flower, this material caps some of the most important agricultural land in the U.S. The Corn belt states grow corn on soils that have developed from this material.


    1. Sand Dunes

      1. locally important in N.C.; beaches, outer Banks, Sandhills

      2. These are all one grain size, sand size

    2. Volcanic ash

      1. ash from volcanoes

      2. important in the Pacific Northwest

  5. Colluvium
    • material moved and deposited by gravity

    • aided by frost action and steep slopes

    • landslides, any sort of soil slip

    • stony soils

  6. Man

    Strip mine soils, garbage dumps, daily cover landfills, polders, etc... All of the se show mans influence on the movement of material. After these materials are moved new soil may begin to form in the newly deposited material.
  7. Organic Parent Material

    • vegetative production exceeds decomposition organic soils are generally peats and mucks

    • usually in poorly drained areas; swamps and marshes

    • oxidation of organic material limited by

    • lack of oxygen

    • too much water

    There are two general types of organic material

    Peat- plant parts are identifiable

    Muck - plant parts are not identifiable: more decomposed