Download Intrusive Landforms File

Intrusive Landforms
Intrusive Landforms
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Intrusive landforms are formed from
bodies of magma cooling below the
Earth’s surface
They form rocks with coarse texture
and visible minerals (granite,
gabbro, diorite) rather than the fine
textured rocks formed by volcanic
landforms (basalt, pumice, scoria)
Shallow Intrusive Structures
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Volcanic neck –
extinct throat of a
volcano
Dike – tabular
igneous bodies that
cut across other
layers and are
nearly vertical or
at steep angles
Black Tusk in
Garabaldi Prov Park
Near
Squamish and
visible from
Hwy 99
Shallow Intrusive Structures
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Sill – nearly
horizontal tabular
igneous bodies
Laccoliths – start
out as sills, but
become wider as
they fill with more
magma (bulged
sills)
Deep Intrusive Structures
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Batholith – a large area (>100 km2) igneous
intrusion
Stocks – smaller area igneous intrusions (<
100 km2)
Deep Intrusive Structures
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Xenoliths = large chunks of older rock
that is included in an igneous rock body
Pluton = A body of intrusive igneous rock
that is crystallized from magma slowly
cooling below the earth’s surface.