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soil profile ![click to hear : soil profile click to hear : soil profile](../../images/speaker-vert.gif)
Soil usually has four main layers; it varies in total thickness from several centimeters to several meters, depending on the area.
bedrock ![click to hear : bedrock click to hear : bedrock](../../images/speaker-vert.gif)
Rock that forms the bottom layer of soil; its physical and chemical breakdown enables the upper layers to develop.
subsoil ![click to hear : subsoil click to hear : subsoil](../../images/speaker-vert.gif)
Third layer of soil to which the roots extend; contains little organic matter but many nutrients leached from the topsoil.
plant litter ![click to hear : plant litter click to hear : plant litter](../../images/speaker-vert.gif)
Upper layer of soil, composed of recently fallen animal and vegetable scraps or those in the early stages of decomposition.
topsoil ![click to hear : topsoil click to hear : topsoil](../../images/speaker-vert.gif)
Second layer of soil, dark in color and rich in organic matter; it contains almost all of the soil’s animal and vegetable life.