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These active margins can be convergent or transform margins, and are also places of high tectonic activity, including volcanoes and earthquakes. The West Coast of North America and South America are active margins. [4] Active continental margins are typically narrow from coast to shelf break, with steep descents into trenches. [4] Convergent ...
On the West coast of North America, the coast ranges and the coastal plain form the margin, which is partially bounded by the San Andreas Fault, a transform boundary of the Pacific Plate. Most of the land is made of terranes that have been accreted onto the margin. In the north, the insular belt is an accreted terrane, forming the margin.
This once-active divergent plate boundary became the passive, trailing edge of westward moving North America. In plate tectonic terms, the Atlantic Plain is known as a classic example of a passive continental margin. [20] During the rifting, South America tore away from North America and headed southward.
The North American plate is a tectonic plate containing most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores.With an area of 76 million km 2 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific plate (which borders the plate to the west).
Passive continental margins such as most of the Atlantic coasts have wide and shallow shelves, made of thick sedimentary wedges derived from long erosion of a neighboring continent. Active continental margins have narrow, relatively steep shelves, due to frequent earthquakes that move sediment to the deep sea.
Age of the bedrock underlying North America, from red (oldest) to blue, green, yellow (newest). Seventy percent of North America is underlain by the Laurentia craton, [5] which is exposed as the Canadian Shield in much of central and eastern Canada around the Hudson Bay, and as far south as the U.S. states of Michigan, Wisconsin, and Minnesota.
A few days ago I penned a column in this space -- Why to Be Glad America Isn't Making TVs Anymore -- pointing out that when America "lost" the television manufacturing industry to Japan back in ...
Image:Blank US Map with borders.svg, a blank states maps with borders. Image:BlankMap-USA.png, a map with no borders and states separated by transparency. Image:US map - geographic.png, a geographical map. On Wikimedia Commons, a free online media resource: commons:Category:Maps of the United States, the category for all maps with subcategories.