GUELPH, ONTARIO - Agriculture and Agri-Food Canada

PART II
FACTORS AFFECTING THE FORMATION OF
BRUCE COUNTY SOILS
Soils are natural bodies found at the surface of the earth in which plants
grow, and are the products of the environmental conditions under which they
have developed. Soil development processes are dependent upon a number
of factors which include climate, vegetation, soil materials, relief, and age.
Soil
Materials
Soils develop from the materials found at the surface of the earth and their
characteristics are influenced to a large extent by the nature of these materials.
Disintegrated rock particles constittite the soil skeleton. The chemical and
physical composition of the mineral parent material influence profile development,
and the movement of soil water within the profile affects the amount of
leaching to which the soil is subjected.
As shown in Figure 4, limestone formations occur in the County in long
relatively narrow belts trending nearly north and south. On the Bruce peninsula
rock outcrops are a frequent occurrence, but in other parts of the County they
are rather infrequent owing to the depth of the unconsolidated cover of drift.
The uppermost bedrock in the area southwest of Walkerton is fine grained
limestone, magnesium limestone and dolomit,e ranging in colour from grey to
brown and belonging to the Norfolk formation. The brownish rock commonly
has dark brown to black bituminous st,reaks parallel to the bedding planes
and the grey or thicker bedded strata may have thin shaly partings along
some of the bedding planes. Next to this formation is a narrow band of the
Bertie-Akron formation running through Walkerton to Southampton which
consists of brown to grey finely crystalline to dense dolomite and dolomitic
limestone. The Salina formation occurs next to the Bertie-Akron series underlying
the soil in Saugeen, Arran and Elderslie Townships. This formation
exhibits alternate grey and brown zones. The brown consists of fine-grained
to dense dolomite and the grey varies from argillaceous dolomite to dolomitic
shale. The Guelph and Lockport formations occupy most of the Bruce Peninsula,
the Guelph formation being situated in the westerly part of the Peninsula.
These formations consist of fine-grained, crystalline, and granular dolomite
which is buff or brownish grey in the upper part becoming grey to almost
white at the base. A narrow streak of the Medina formation occurs along the
easterly side of the Bruce Peninsula. Although this formation is made up of
three members, the Manitoulin member is the principal member found on the
Peninsula. The rock is grey to blue-grey, medium to fine-grained, thinly
bedded, compact and semi-crystalline. The weathered surface is usually
stained and rough, due apparently to the rock being composed of layers of
unequal hardness. The Queenston formation occurs on Cape Croker and is
typically a brick-red, argillaceous and sandy shale with many green bands
and mottlings.
Analyses of the Bruce County bedrock formations are presented in Table 2.
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