The Soils of The Regional Municipality of Ottawa=Carleton

General Land Use Except for the very poorly drained soils of
the association, North Gower soils have a high agricultural
capability for common field crops . They are used for corn,
cerealgrain, and hay production on a broad scale.
Correlation to Ottawa Urban Fringe In the survey of the
Ottawa Urban Fringe, theNorth Gower variant was mapped as
a phase and denoted with a "V" attached to the respective soil
landscape unit to which it applied . In this survey, the variant
was identified and mapped as a separate soil landscape unit,
namely the NG5 unit .
North Gower soils in the survey area are similar to those of
the Urban Fringearea in chemical and physical characteristics
with one exception . In the imperfectly drained soils mapped,
eluvial and illuvial horizons seldom occurred . The absence of
these horizons, therefore, necessitated an additional taxonomic
classification for those soils .
OKA (O)
Location and Extent Soils of the Oka association occur in
each of the three map areas ofthe survey area . Theyoccur most
extensively, however, in Rideau, Goulbourn, and West Carleton
townships primarily on the Paleozoic bedrock plains of
those areas . Approximately 5,600 ha of Oka soils were
mapped, of which 3,000 ha were mapped in combination with
soils of other associations .
Landform and Topography Oka association soils have developed
on very gently to moderately sloping marine beach materials
. Slopes most commonly range between 2 and 9% . Most
often the beach materials occur on bedrock controlled landscapes,
primarily those in which Farmington association soils
underlain by dolomite or limestone bedrock are found . In this
case, wave action during thetime ofthe Champlain Seaformed
raised beaches which range from less than 1mto several metres
in thickness over bedrock . These landscapes are usually ridged
and have very gently to gently sloping topography. Oka soils
also have developed on marine beach materials which overly
glacial till, mainly in the form of drumlinoid ridges . Wave
action in this case has formed beaches on the side of many
ridges on the mid to upper slope positions and crests . Oka soils
of this type were identified in the North Gower, Richmond,
and Manotick areas of Rideau Township . The resultant landscapes
are steeper than in bedrock controlled landscapes, often
being moderately sloping with slopes ranging from 9 to 15% .
A third landscape situation in which Oka soils occur is marine
beaches formed on glaciofluvial deposits . In this instance,
meltwater from glacial retreat produced esker and other ice
contact deposits which were subsequently reworked to varying
degrees into beaches during the Champlain Sea inundation
which followed glaciation . Soils occurring on the reworked ice
contact deposits were mapped as the Kars association where
marine reworking was minimal and not easily recognized .
Where beach formation was substantial and easily recognizable
on these landscapes, the soils were mapped as the Oka
association .
Soil Material Oka association soil materials consist of gravelly
to very gravelly, coarse to moderately coarse textured
marine beach materials which overly either Paleozoic
bedrock, glacial till, or glaciofluvial ice contact deposits . The
parent material is commonly grayish to dark grayish brown in
color, and has coarse sandy loam, loamy coarse sand, or coarse
sand textures . Highly representative Oka soils are mildly alkaline
in reaction and moderately to strongly calcareous . Occasionally
some may be extremely calcareous . The alkalinity and
calcareousness of the materials results from the high proportion
of limestone and dolomtic rock fragments which are
present . Some Oka soils were also mapped on small beach formations
which have resulted from wave action on glacial till
deposits derived from gray-green and red shale bedrock . These
materials occur infrequently and were included in the association
due to their limited extent . They possess similar textures
and have a high gravel content which primarily consists of
channery sized shale fragments . Soil reaction of the parent
material ofthese shaly beach materials ranges from neutral to
slightly acidic. The more representative calcareous Oka soil
materials in which limestone and dolomite rock fragments are
the dominant coarse fragments were designated by either the
01 or 02 soil landscape units. The noncalcareous shaley materials
were designated by either the 03 or 05 soil landscape
units .
Coarse fragment (gravel) content of Oka materials usually
exceeds 40% by weight and may range as high as 80% in some
materials . The amount of coarse fragments increases with
depth and is greatest in the parent material or Ck horizons .
Coarse fragment type, size, and shape are quite variable and
are dependent onthe type ofbeach formation . Those resulting
from wave deflated glacial till are primarily composed of limestone
or dolomite fragments consisting of very angular gravel,
angular and subrounded stones, and occasional boulders . Oka
materials resulting from subsequent wave action on shallow
glacial drift material overlying Paleozoic bedrock are predominantly
composed of flat, angular fragments of limestone and
dolomite . The materials may be either channery, flaggy, or
both . The third type of Oka material resulting from wave
action on glaciofluvial deposits is mainly composed of
rounded and subrounded cobbles and stones . Although primarily
of limestone and dolomite origin, some fragments of
granite and gneiss of Precambrian origin are also present .
Oka soil materials tend to be somewhat finer textured at
the surface . Surface textures of loamy sand, sandy loam, or
loam occur most often . In addition, some materials may have
free carbonates inthe surface and B horizons .
Soil Moisture Characteristics Oka association soils aredominantly
rapidly to well-drained, with imperfectly drained soils
also occurring but to a considerably lesser extent . Due to their
coarse textures and high coarse fragment content, Oka materials
are rapidly permeable and have a low water holding capacity.
Clay illuviation, designated by Btj and Bt horizons, when
present in these soils reduces permeability somewhat and
increases the water holding capacity slightly. Surface runoff is
slow.
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