Shield (geology) in the context of "Platform (geology)"

Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and metamorphic rocks and constitute an important element of some sediments and sedimentary rocks. For these reasons, in geology, volcanics and shallow hypabyssal rocks are not always treated as distinct. In the context of Precambrian shield geology, the term "volcanic" is often applied to what are strictly metavolcanic rocks. Volcanic rocks and sediment that form from magma erupted into the air are called "pyroclastics," and these are also technically sedimentary rocks.

Volcanic rocks are among the most common rock types on Earth's surface, particularly in the oceans. On land, they are very common at plate boundaries and in flood basalt provinces. It has been estimated that volcanic rocks cover about 8% of the Earth's current land surface.

Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.

The magma can be derived from partial melts of existing rocks in a terrestrial planet's mantle or crust. Typically, the melting is caused by one or more of three processes: an increase in temperature, a decrease in pressure, or a change in composition. Solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses.

The word orogeny comes from Ancient Greek ὄρος (óros) 'mountain' and γένεσις (génesis) 'creation, origin'. Although it was used before him, the American geologist G. K. Gilbert used the term in 1890 to mean the process of mountain-building, as distinguished from epeirogeny.

The Western Plateau is Australia's largest drainage division and is composed predominantly of the remains of the ancient rock shield of Gondwana. It covers two thirds of the continent; 2,700,000 square kilometres (1,000,000 sq mi) of arid land, including large parts of Western Australia, South Australia, and the Northern Territory. For comparison, it is roughly the same size as the whole of continental Europe from Western Poland to Portugal.

The western plateau extends from the Gulf of Carpentaria to Onslow, covering the cities of Perth and Albany. The Western Plateau occupies almost two-thirds of the land surface of Australia and it covers parts of Western Australia, Northern Territory and South Australia