Soils of the - Agriculture and Agri-Food Canada

Location and Extent : Crescent soils are common on Westham and Crescent islands, in the southern part o f
Richmond Municipality and southwest of Ladner There are about 990 ha of pure map units and 1040 ha of soi l
complexes dominated by Crescent soils . Most complexes are with Westham and Ladner soils .
Topography and Elevation : Crescent soils are usually nearly level or gently undulating with slopes les s
than 2 percent minor areas are undulating with slopes to 4 percent . Land levelling has occurred in many areas .
Elevations are all less than 5 m above sea level .
Parent Material and Texture : The parent material of Crescent soils are medium to moderately fine textured ,
stone-free, deltaic deposits of the Fraser River, usually deeper than 1 m and underlain by saline sand . Surface ,
subsurface and subsoil textures are mainly silt loam, sometimes varying to silty clay loam . At depths of 1 m o r
more, textures usually change to sand or loamy sand and at these depths a variety of sulphurous compound s
are likely to be present .
Soil Moisture Characteristics : Crescent soils are moderately poorly to poorly drained . They are moderately
pervious and have slow surface runoff and high soil water holding capacity . The watertables are often nea r
the soil surface during winter months but artificial drainage by ditches, subsoil drains and pumping is sufficien t
to provide an adequate saturation-free rooting zone during most growing seasons . Some subsoil irrigation i s
also possible by watertable control during dry summer periods . Saline conditions exist below about 120 cm bu t
have little effect on most of the rooting zone . Almost all areas are protected by dykes from flooding during hig h
tides and flood stages of the Fraser River .
u-
General Soil Description : Crescent soils have a friable to firm, dark grayish brown . silty, cultivated surface
about 20 cm thick which is underlain by about 20 cm of dark gray . firm, silty material that breaks to prismatic o r
blocky clods and contains many, yellowish-red mottles as well as thin clay skins and clay flows . This laye r
grades to at least 50 cm of massive, silty material containing common, yellowish-red to dark reddish brow n
7 mottles and, in the lower part, hard . brownish tubules around old root channels . Underlying this is either gray to
olive-gray, saline and sulphurous, fine sand or alternating lenses of sand and silt containing a few reddish -
brown mottles and hard tubules . Soil reaction ranges from medium or strongly acid in the surface an d
Plate 17 A landscape typical of parts of
Richmond Municipality, Westham Islan d
and western Delta Municipality. Crescent,
Westham, Delta and Ladner soils are the
usual soils developed in these nearly leve l
to gently undulating poorly drained, silty to
clayey deltaic deposits
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