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Geologic Tilting
What Causes Geologic Tilting?
By Audrey
Farley
Geologic
tilting, also known as tectonic tilting, occurs when the earth’s surface layers
begin to tilt or slant irregularly.
Geologists
have studied the tilts of land, lakes and other bodies of water for hundreds of
years and developed different theories to account for geologic tilting.
Although
there is disagreement about certain causes of tilting, it is generally accepted
that tilting can occur as a result of faults (vertical and horizontal), angular
unconformity and disturbances to the earth’s magnetic field.
Vertical Faults
A fault is a crack or fissure in the earth’s crust.
Typically,
faults cause movement in the earth’s surface, triggering phenomena like
earthquakes.
One
kind of movement that faults trigger is vertical. For instance, when mountains
or tall elevation in the earth’s surface crack, mountain blocks (the layers of
the earth that form the mountain) move relative to the fault and displace the
ground surface.
The
displacement of the surface may be mild or severe but typically causes tilting
or irregularity in the surrounding land.
Horizontal
Faults
Horizontal cracks can occur underneath the earth’s surface
or on the surface. The latter are known as surface fault ruptures.
Horizontal
faults, like vertical faults, disturb the formation of the earth’s layers and
cause irregularities, including tilting.
Surface
fault ruptures can also cause tectonic subsidence, which is broad tilting of
the valley floor.
When
valley floors tilt, lakes and reservoirs near the valley floor flood and
tributary courses are disturbed.
Angular Unconformity
Angular unconformity also causes geologic tilting.
Angular
unconformity occurs when parallel strata of sedimentary rocks are deposited on
layers that are tilted, perhaps as a result of erosion.
In
short, new layers of sedimentary rocks are compressed on top of layers that are
already deformed and tilting, thereby exacerbating tilting and causing further
angular discordance.
Changes
to Magnetic Field
Disturbances in the earth’s magnetic field also cause
geologic tilting.
Diverse
phenomena have the potential to disturb the earth’s magnetic field, including
passing comets or fluctuations in the sun’s magnetic field.
No
matter when magnetization is disturbed, the terrestrial axis of the earth is
altered. This causes all kinds of geologic and climatological imbalances,
including the tilting of lakes and layers of the earth’s surface because of
subcrust migration.
Essentially,
the displacement of magnetic poles causes crustal displacements and other
irregularities by dislocating (even over hundreds of years) the underlying
strata of the earth.
About
the Author
Audrey Farley
began writing professionally in 2007. She has been featured in various issues
of "The Mountain Echo" and "The Messenger." Farley has a
Bachelor of Arts in English from the University of Richmond and a Master of
Arts in English literature from Virginia Commonwealth University. She teaches
English composition at a community college.
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