Soils of the - Agriculture and Agri-Food Canada

MARION SOILS (MN)
Location and Extent : Marion soils occur only in a few, small areas, mostly on the University of Britis h
Columbia Research Forest . It is mapped only as a secondary soil in soil complexes, usually with Blaney soils .
Topography and Elevation : Marion soils are strongly to steeply sloping or moderately to strongly rolling ,
with slopes between 10 and 30 percent . They usually occupy lower slope positions or shallow depressions i n
the uneven landscape . Elevations lie in the vicinity of 400 m above sea level .
Parent Material and Texture : Marion soils have developed from moderately coarse to coarse-textured ,
stony glacial till derived mainly from granitic rock . The deposits are usually more than 1 m but less than 3 m dee p
over bedrock . Surface, subsurface and subsoil textures vary from gravelly loamy sand to gravelly sandy loam .
Discontinuous, moderate cementation is often present in the subsurface while the subsoil is continuously ,
strongly cemented below about 70 cm .
Soil Moisture Characteristics : Marion soils are imperfectly drained . They are rapidly pervious in th e
surface and subsurface but this decreases abruptly to slowly pervious in the cemented subsoil . They have low
to moderate water holding capacity and slow to moderate surface runoff . During the rainy winter and after othe r
heavy rains a periodic, perched watertable develops above the cemented subsoil and variable amounts o f
telluric seepage develops along the surface of the cemented layer .
General Soil Description : Marion soils generally have from 10 to 25 cm of organic forest litter on the minera l
soil surface, the lower half of which is black, friable and well-decomposed . This is abruptly underlain by 5 to 1 0
cm of grayish, strongly leached, friable, sandy material, which, in turn, is underlain by about 25 cm of dar k
brown or dark reddish brown, blocky, firm, discontinuously cemented, sandy or gravelly material containin g
between 10 and 15 percent organic matter. This grades to about 50 cm of olive-brown or olive, discontinuousl y
cemented, firm, sandy or gravelly material containing many, prominent dark reddish brown or reddish-brow n
mottles. The lower 5 cm usually contains a well-defined zone of root concentration (root mat) . Abruptl y
underlying this is a massive, gravelly or sandy zone at least 25 cm thick that is gray or olive-gray, very strongl y
cemented to indurated and contains common, strong brown mottles . This cemented zone then graduall y
grades below 1 m to grayish, unweathered glacial till or overlies bedrock . Soil reaction ranges from extremel y
acid in the upper soil to strongly acid below about 70 cm . Soil classification is usually Duric Ferro-Humic Podzol.
Ortstein Ferro-Humic Podzols also occur in a few areas where the subsurface layers are more strongl y
cemented than usual .
Commonly Associated Soils : Blaney, Cannell and Eunice soils are usually closely associated with Mario n
soils . Blaney soils are similar to Marion soils except that they are well to moderately well drained, rather tha n
imperfectly drained and lack the well-defined mottling on the subsoil . Cannell soils differ from Marion soils b y
having bedrock within 1 m of the surface while Eunice soils differ by consisting of 10 cm or more of organic fores t
litter over bedrock .
Vegetation : Most areas of Marion soils have been logged in the past . Currently they support a second-growt h
forest consisting mainly of western hemlock, western red cedar and coast Douglas-fir interspersed with re d
alder and vine maple . Rooting depth restricted to about 75 cm by the cemented subsoil .
General Land Use Comments : (1) Marion soils are poorly suited for agriculture because of advers e
topography and stoniness . (2) Urban and related uses are also poorly suited for Marion soils . Steep slopes ,
periodic perched watertables and seepage as well as relatively shallow bedrock are all limitations . Inefficient
septic tank operation can be expected due to cemented, slowly permeable subsoils and steep slopes . (3 )
Forest growth is good . Data from a limited number of plots indicates annual potential wood production b y
western hemlock and western red cedar to be between 12 and 15 m 3/ha .
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