#MAJORandMINORTECTONICPLATES Primary Tectonic Plates Secondary Tectonic Plates African Plate Arabian Plate Antarctic Plate Caribbean Plate Australian Plate Cocos Plate Eurasian Plate Juan de Fuca Plate Indian Plate Nazca Plate North American Plate Philippine Sea Plate Pacific Plate Scotia Plate South American Plate There are 8 primary plates on the planet (or 7 if you count the Indo-Australian Plate as a single plate), and they comprise of the majority of the Worlds continents landmass, along with most of the surface area of the Worlds Oceans. The secondary plates are smaller in size than the primary plates, and they do not cover any substantial landmass, apart from the Arabian Plate. There are a further group of smaller plates, often called tertiary plates, which are the disappearing remains of much larger ancient plates that are now on the edges of our major plates, plus some micro-plates, many of whom will be widely-considered as a part of a primary or secondary plate on maps and in scientific publications. #WHATARETECTONICSPLATE The tectonic plates are a series of plates which cover the entire surface of planet Earth. They can have a depth of up to an estimated 100 km, and are comprised of the entire planets crust, most of the moho, and a tiny piece of the upper mantle. This collective area of rocky planets is generally called the lithosphere. NOTE* The moho - also know as the Mohorovičić discontinuity - is a layer of unknown composition which planet Earths crust physically rests upon. It is situated about 5-10 km below the ocean floor and 20-90 km beneath continents. The overall estimated average thickness of the moho is thought to be about 35 km. The term tectonic plates has been historically used by scientists to describe the movement of the lithosphere, however, nowadays the term tectonic plates is most widely-used for describing the physical plates themselves, rather than their movement. The top layer of the tectonic plates - the crust - is continually moving gradually, just like a slow conveyor belt, with new crust appearing on one side of each plate, and disappearing into another boundary it shares with a neighbouring plate. #WHATISTHECRUSTMADEFROM The upper layer of the tectonic plates - the crust - was produced by substances which have flowed from the inside of our planet. Oceanic crust consists mainly of basaltic rocks which are rich in magnesium, iron and some silicates, with lower density granitic rocks dominating continental crusts, which are enriched in mostly lighter elements, including oxygen, aluminium, sodium, silicon, and potassium. Due to the recycling nature of the tectonic plate movement, the oldest ocean crust is though to be about 200 millions years old, and the oldest continental crust is believed to be about four billion years old.
Posted on: Mon, 14 Jul 2014 05:36:21 +0000
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