Soils of the - Agriculture and Agri-Food Canada

ROACH SOILS (RH)
Location and Extent : Roach soils occur on the uplands and at the lower elevations in the mountains north of
the Fraser River, mainly in the vicinity of Steelhead and in the Norrish and Statlu Creek valleys . About 1810 ha of
pure map units and 2390 ha of soil complexes dominated by Roach soils are mapped . The complexes are
mostly with Errock, Keystone, Buntzen, Fellows and Stave soils .
Topography and Elevation : Roach soils have variable topography, ranging from undulating or moderatel y
sloping to very steeply sloping or hilly. Slope gradients range from 5 to 50 percent . Elevations usually li e
between 150 m and 500 m above sea level .
Parent Material and Texture : The parent material of Roach soils is coarse-textured, gravelly and stony ,
often stratified glaciofluvial deposits . In some areas, small areas of alluvial fan deposits are included . Surface
textures vary from gravelly loamy sand to gravelly sandy loam . In a few locations a thin (less than 15 cm thick) ,
loam surface layer is present . The subsurface and subsoil range from stony gravel to gravelly sand and ar e
strongly cemented .
Soil Moisture Characteristics : Roach soils are moderately well to well drained . They are rapidly perviou s
and have low water holding capacity and slow surface runoff . Temporary, perched watertables sometime s
develop above the cemented layer during and after heavy, prolonged rains and telluric subsoil seepage occur s
in this zone during these times, particularly in areas with long, uniform slopes .
General Soil Description : Roach soils generally have between 8 and 15 cm of organic forest litter on th e
soil surface, the lower half of which is black to dark reddish brown and well to moderately decomposed . Unde r
this is 5 to 10 cm of gray to pinkish-gray, friable, strongly leached, sandy material which, in turn, is abruptl y
underlain by about 15 cm of dark reddish brown, friable, stony, gravelly and sandy material containin g
scattered, moderately cemented pockets . Below this occurs a zone about 50 to 150 cm thick which is dark
reddish brown in the upper part and yellowish-red, reddish-brown or yellowish-brown in lower part, is ver y
strongly cemented, extremely hard, and consists mainly of stony gravel and sandy gravel . This cemented zon e
then gradually grades into loose, stony and gravelly unweathered soil parent material . Soil reaction varies fro m
extremely acid near the surface to strongly acid in the subsoil . Soil classification is dominantly Ortstein Ferro-
Humic Podzol although small areas of Duric Ferro-Humic Podzol are also included .
Commonly Associated Soils : Errock, Keystone, Fellows and Stave soils often occur in close associatio n
with Roach soils . Errock soils are similar to Roach soils except they are imperfectly drained and usually lie a t
slightly lower landscape positions . Keystone soils differ from Roach soils by having loamy surfaces ; also ,
cementation only occurs in the lower subsoil . Both Fellows and Stave soils differ from Roach soils by bein g
sandy in texture .
Vegetation : Most areas of Roach soils have been logged and now support second-growth coast Douglas-fir ,
western hemlock and western red cedar, red alder and a variety of shrubs and ground cover . Rooting i s
restricted mainly to the upper 50 cm by the strongly cemented subsurface and subsoil layers .
General Land Use Comments : (1) Roach soils have limited use for agricultural crops because o f
restrictions imposed by adverse topography, low moisture and nutrient holding capacity and excessiv e
stoniness . (2) In areas which have relatively subdued topography, Roach soils are moderately suited for urba n
and related purposes . Soil bearing strengths are high and groundwater tables are not a problem . Basements ,
underground utilities and other excavations are hindered by the stony nature of the soils . Septic tank effluen t
disposal is satisfactory since tile fields are usually below the cemented zone, however incomplete effluen t
filtration is likely due to the coarse soil texture . Areas of Roach soils are potential sources of aggregate and fill ,
although the stony character of the soil material may limit their use for some purposes . (3) Forest growth is onl y
moderate, apparently limited by droughty conditions and restricted rooting due to subsurface cementation .
Data from limited measurements indicates potential annual wood production by Douglas-fir is 5 to 6 .5 m 3/ha .
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