Terrane in the context of "Euramerica"

A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, usually an orogeny. Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets.

Mountain ranges are usually segmented by highlands or mountain passes and valleys. Individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology. They may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, and volcanic landforms resulting in a variety of rock types.

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 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific plate (which borders the plate to the west).

It extends eastward to the seismically active Mid-Atlantic Ridge at the Azores triple junction plate boundary where it meets the Eurasian plate and Nubian plate.and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust. The interior of the main continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of crustal material called terranes, which are accreted to the craton by tectonic actions over a long span of time. Much of North America west of the Rocky Mountains is composed of such terranes.

Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by relatively uniform lithology. The largest of these fault blocks are called crustal blocks. Large crustal blocks broken off from tectonic plates are called terranes. Those terranes which are the full thickness of the lithosphere are called microplates. Continent-sized blocks are called variously microcontinents, continental ribbons, H-blocks, extensional allochthons and outer highs.

Because most stresses relate to the tectonic activity of moving plates, most motion between blocks is horizontal, that is parallel to the Earth's crust by strike-slip faults. However vertical movement of blocks produces much more dramatic results. Landforms (mountains, hills, ridges, lakes, valleys, etc.) are sometimes formed when the faults have a large vertical displacement. Adjacent raised blocks (horsts) and down-dropped blocks (grabens) can form high escarpments. Often the movement of these blocks is accompanied by tilting, due to compaction or stretching of the crust at that point.

A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields or volcanic systems. Volcanic belts are found above zones of unusually high temperature (700 to 1,400 °C (1,292 to 2,552 °F)) where magma is created by partial melting of solid material in the Earth's crust and upper mantle. These areas usually form along tectonic plate boundaries at depths of 10 to 50 kilometres (6.2 to 31.1 mi). For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 kilometres (560 mi) from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada. In the case of Iceland, the geologist G.G. Bárdarson in 1929 identified clusters of volcanic belts while studying the Reykjanes Peninsula.

The deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield. It contains over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 1,200 million years old. These are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that form what are known as greenstone belts. They are thought to have formed at ancient oceanic spreading centers and island arc terranes. The Abitibi greenstone belt in Ontario and Quebec, Canada is one of the world's largest greenstone belts.