Soils of the - Agriculture and Agri-Food Canada

CHEAM SOILS . (CM )
Location and Extent : Cheam soils only occur in a few, scattered areas on the uplands . There are about 75 h a
of Cheam-Isar soil complex .
Topography and Elevation : Cheam soils are strongly to very steeply sloping with slope gradients betwee n
10 and 40 percent . They lie between 75 and 200 m above sea level .
Parent Material and Texture : Cheam soils have developed from coarse-textured colluvial (landslide an d
rockfall) deposits mixed with small amounts of alluvial fan deposits . The deposits are more than 1 m deep and -
overlie either bedrock or glacial till . Surface, subsurface and subsoil textures range from gravelly sandy loam t o
gravelly loamy sand and include lenses of gravel . High proportions (usually more than 50 percent by volume) o f
angular stones, cobbles and boulders are present .
Soil Moisture Characteristics : Cheam soils are well to rapidly drained . They are rapidly pervious and have
slow surface runoff and low water holding capacity. Variable amounts of seepage is sometimes present in th e
lower subsoil, near the contact with the underlying bedrock or glacial till .
General Soil Description : The surface of Cheam soils consists of a thin layer (usually less than 5 cm thick )
of forest litter. This is underlain by a loose to friable, sandy, gravelly and stony, dark brown or dark reddish brow n
layer about 20 cm thick . This layer, in turn is underlain by a 30 cm thick transitional zone consisting of dar k
yellowish brown, gravelly, stony and bouldery material that grades to olive-brown, unweathered soil paren t
material below about 60 cm . Soil reaction usually is strongly acid . Soil classification is Orthic Humo-Ferric
Podzol.
Commonly Associated Soils : Isar soils are almost always closely associated with Cheam soils . Isar soil s
differ from Cheam soils by being of fluvial fan rather than colluvial origin . They are of recent deposition and eithe r
have no, or only slight soil profile development (are regosolic) .
Vegetation : The vegetation on Cheam soils consists mainly of second-growth coast Douglas-fir, wester n
hemlock, western red cedar, bigleaf maple, birch and red alder, understoried by a variety of shrubs and herbs .
Rooting is usually unrestricted in the upper 75 cm but may be partially impaired below that by numerous stones
and boulders .
General Land Use Comments : (1) Cheam soils are generally poorly suited for arable agriculture due to
excessive stoniness and steep slopes ; some areas may be developed for pasture . (2) Urban uses are als o
restricted by very stony and bouldery soils and steep slopes ; some areas may also be susceptible to furthe r
mass movement hazard . (3) Moderate forest growth occurs and is limited by low soil moisture holding capacity .
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