It extends eastward to the Mid-Atlantic Ridge
and westward to the Chersky Range
in eastern Siberia. The plate includes both continental
and oceanic crust
. The interior of the main continental landmass includes an extensive granitic
core called a craton
. Along most of the edges of this craton are fragments of crustal material called terranes
, which are accreted
to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the Rocky Mountains
is composed of such terranes.
It is generally accepted that a piece of the North American Plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. However, it is as yet unclear whether the oceanic crust east of the Rise and west of the mainland coast of Mexico is actually a new plate beginning to converge with the North American Plate, consistent with the standard model of rift zone spreading centers generally.
For the most part, the North American Plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge at a rate of about 2.3 centimeters (~1 inch) per year. At the same time, the Pacific Plate is moving to the northwest at a speed of between 7 and 11 centimeters (~3-4 inches) a year.
The motion of the plate cannot be driven by subduction as no part of the North American Plate is being subducted, except for a small section comprising part of the Puerto Rico Trench
; thus other mechanisms continue to be investigated.
One recent study suggests that a mantle convective current is propelling the plate.
- ^ "Sizes of Tectonic or Lithospheric Plates". Geology.about.com. 2014-03-05. Archived from the original on 2016-06-05. Retrieved 2016-01-11.
- ^ "Landslides, Floods, and Marine Effects of the Storm of January 3-5, 1982, in the San Francisco Bay Region, California". pubs.usgs.gov. Archived from the original on 2018-07-20. Retrieved 2020-03-13.
- ^ "Farallon Plate [This Dynamic Earth, USGS]". pubs.usgs.gov. Archived from the original on 2020-01-30. Retrieved 2020-03-13.
- ^ "Hotspots [This Dynamic Earth, USGS]". pubs.usgs.gov. Archived from the original on 2020-04-09. Retrieved 2020-03-13.
- ^ "Geotimes - November 2000: New Notes". www.geotimes.org. Archived from the original on 2018-07-11. Retrieved 2008-03-29.
- ^ "Upper-mantle origin of the Yellowstone hotspot" (PDF). Archived (PDF) from the original on 2007-07-03. Retrieved 2008-03-29.
- ^ Eaton, David W.; Frederiksen, Andrew (2007). "Seismic evidence for convection-driven motion of the North American plate". Nature. 446 (7134): 428–431. Bibcode:2007Natur.446..428E. doi:10.1038/nature05675. PMID 17377580. S2CID 4420814.
- ^ Feldman, Jay (2005). When the Mississippi Ran Backwards : Empire, Intrigue, Murder, and the New Madrid Earthquakes. Free Press. ISBN 978-0-7432-4278-3.
Last edited on 18 March 2021, at 20:15
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