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List of tectonic plates
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<p>This is a list of tectonic plates on <a href="/facts/Earth/HLLmDfj0">Earth's surface</a>. <a href="/facts/Plate_tectonics/RtRG5lY4">Tectonic plates</a> are pieces of <a href="/facts/Earth%27s_crust/VSy2u31r">Earth's crust</a> and uppermost <a href="/facts/Mantle_(geology)/RpDdtjCr">mantle</a>, together referred to as the <a href="/facts/Lithosphere/1mqaxASd">lithosphere</a>. The plates are around 100 km (62 mi) thick and consist of two principal types of material: <a href="/facts/Oceanic_crust/0lGjI7jN">oceanic crust</a> (also called <i><a href="/facts/Sima_(geology)/0n4Ytwsv">sima</a></i> from <a href="/facts/Silicon/cgWx0hdr">silicon</a> and <a href="/facts/Magnesium/XyIhd2FG">magnesium</a>) and <a href="/facts/Continental_crust/cGnK3oEr">continental crust</a> (<i><a href="/facts/Sial/DupWmjRP">sial</a></i> from silicon and <a href="/facts/Aluminium/7wmR8jYE">aluminium</a>). The composition of the two types of crust differs markedly, with <a href="/facts/Mafic/mVL7Ahuw">mafic</a> <a href="/facts/Basalt/uhbwGPTb">basaltic</a> rocks dominating oceanic crust, while continental crust consists principally of lower-<a href="/facts/Density/92p6hh9I">density</a> <a href="/facts/Felsic/0jpm1eSA">felsic</a> <a href="/facts/Granite/G2evuVKo">granitic</a> rocks. </p>