Sheet intrusion
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A sheet intrusion, or tabular intrusion, is a planar sheet of roughly the same thickness, that forms inside a pre-existing rock. When it cuts into another unlayered mass, or across layers, it is calle
A sill of monzonite intrudes Cambrian carbonate bedrock, near Notch Peak, Utah.
Laccolith
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A laccolith is a body of intrusive rock with a dome-shaped upper surface and a level base, fed by a conduit from below. A laccolith forms when magma rising through the Earth's crust begins to spread o
Sheet intrusion
…existing rocks, solidifies into large thin sheets of igneous rock. They are among the most extensive igneous features on Earth, in the form of dikes, laccoliths, cone sheets and sills. When limestone or other precipitate forms in a fault space, it is a sedimentary sheet intrusion…
Idealized laccolith shape
Dolerite intrusion laccolith in Sydney, Australia
Laccolith exposed by erosion of overlying strata in Montana
Pink monzonite laccolith intrudes within the grey Cambrian and Ordovician strata near Notch Peak, Utah