Page 4 - Grp3-Soil magazine (Final-Vid ver)
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3) TYPE OF ROCKS
Igneous rocks can be coarse grained or fine
grained depending on whether the cooling
occurred rapidly or slowly after the erupting of
volcanoes then solidify the magma. They have
high bearing capacity and good foundation
material. Granite produces silty sand, sandy silt
with some clay whereas basalts produces
clayey soil.
They are formed by the weight of the overlying
strata which causes the pressure on the lower
layers then hardens the deposits after a period
of time as layers accumulate at a site. They can
be identified easily when their layer
appearance is observable. Shales can produce
clays, silts and sand stones produce sandy soil,
and for lime stones produce variety type of soil.
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They produced when sedimentary and igneous
rock change their texture and structure as well
as mineral and chemical composition due to
the heat, pressure and shear. Granite
metamorphoses to gneiss; shale to slate and to
schist and limestone change to marble.
Gneiss and shale can produce silt-sand soil
whereas quartzite produce coarse grained soil
such as sands or gravels.
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