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PLATE TECTONIC JHES LOCATION MAP
Geologists use the Theory of Plate Tectonics to better understand the evolution of orogenies (mountain-building events) - as well as the occurrence of rock types (igneous, sedimentary,
and metamorphic) and economic minerals. Figure 1 gives the relative location of the various plates (large, rigid slabs of solid rock) and active volcanoes, while Figure 2 illustrates the
progression (a, b, c) of normal and reversed polarity recorded in the mafic (rich in iron and magnesium) rocks which form along divergent plate boundaries - part of the evidence that
gives credence to this Theory. The “Ring of Fire” on Figure 1 refers to the semi-circular ring of active volcanoes along the Pacific Plate.
Divergent plate boundaries exist at spreading centers - such as the Mid-Atlantic Ridge and the East Pacific Rise - where new sea floor is created by the upwelling of magma.
Transform plate boundaries occur where two plates “slide” past each other horizontally - the San Andreas Fault System is a well-known example of this type of boundary.
Convergent plate boundaries are located where (1) one plate is being subducted (moving under) another plate - for example, at the Aleutian Trench, the Java Trench, and to the west of
the Cascade Range - and (2) where two plates collide to form a mountain range - the Himalaya Mountains are a product of this type of boundary.
The study of the location, depth, and magnitude of the earthquakes that occur along these plate boundaries aid in the comprehension of the natural forces at work on our Earth.
Figure 2. Illustration of the progression (a, b, c) of
magnetic reversals recorded in the sea floor along a
divergent plate boundary (such as the Mid-Atlantic Ridge
or the East Pacific Rise) as the plates move away from
the ridge.
Figure 1.
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Source of Mapping: US Geological Survey
- Not to Scale -
JHES is located on the North American Plate.
The eastern coast of North America is
considered to be a “passive margin” - as
opposed to the western coast, which is
geologically active (think San Andreas Fault
System and Mount St. Helens!).
The geologic history of our Earth can be
explored at http://pubs.usgs.gov/gip/dynamic/
dynamic.html#anchor10790904
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active volcano
Source of Mapping: US Geological Survey http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/Maps/map_plate_tectonics_world.html
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JHES
J Hockenberry Environmental Services, Inc.
2402 William Penn Avenue, Suite 2
Johnstown, PA 15909
© J Hockenberry Environmental Services, Inc.
October 2009 ‘η ’Áξια