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Orogeny
A geologically violent
event in which mountain ranges are built, volcanoes go off, and a lot of
earthquakes occur. This happened when the oceanic and continental plates
met each other.
Plate Tectonics
The crust of
the earth is divided into 14 interlocking pieces called plates, and they
move. Tugged from below by hot, nearly molten rock in the earth’s mantle,
the plates jostle at their edges in collision as they slip past each
other. Plate tectonics is the study of this process.
Thrust Faulting
When a region
of sedimentary rock is squeezed from the sides, it tends to split into
slabs that ride up over another, a process called thrust faulting.
Up-Piling
The Canadian Rockies
grew taller from a buildup of folded and over thrust rock, not from uplift
from below.
Exercise To Visualize Thrust
Faulting
The entire Canadian Rockies must have moved
northeastward along a big thrust fault at the base of the heap of
mountains. It’s like pushing the skin on the back of your hand along with
the thumb, causing wrinkling ahead of the thumb. The skin slides on the
ligament layer underneath just as the sedimentary rock of the Canadian
Rockies has come loose and slid on the basement rock underneath.
From Handbook of the Canadian Rockies by
Ben Gadd; Corax Press, Jasper, Alberta, 1995
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