Sources are from NationalGeographic.org
"Decompression melting involves the upward movement of Earth's mosty-solid mantle. ... Decomposition melting often occurs at divergent boundaries, where tectonic plates separate. The rifting movement causes the buoyant magma below to rise and fill the space of the lower pressure. The rock then cools into new crust."
The North Sea has very important natural resources such as oil and natural gas. Oil is a mixture of organic compounds, mainly hydrocarbons insoluble in water, it is also known as crude oil or simply crude and gas natural which is an important source of fossil energy released by its combustion.
The Mongols set up a tribute empire called The Golden Horde. Serfdom arose as peasants gave up their lands to the aristocracy in exchange for protection from the Mongols. Moscow benefited financially by acting as a tribute collector for the Mongols. Mongol rule kept Russia culturally isolated from Western European trends such as the Renaissance.
