A lava plain, also called a lava field or lava bed, is a large expanse of nearly flat-lying lava

Lava

Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

 flows. Such features are generally composed of highly-fluid basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

 lava, and can extend for tens or even hundreds of miles across the underlying terrain. The extent of large lava fields is most readily grasped from the air or in satellite photos, where their typically dark, nearly-black color contrasts sharply with the rest of the landscape.

Some of the most ancient geological remnants of basaltic plain

Plain

In geography, a plain is land with relatively low relief, that is flat or gently rolling. Prairies and steppes are types of plains, and the archetype for a plain is often thought of as a grassland, but plains in their natural state may also be covered in shrublands, woodland and forest, or...

s lie in Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

's Precambrian Shield

Canadian Shield

The Canadian Shield, also called the Laurentian Plateau, or Bouclier Canadien , is a vast geological shield covered by a thin layer of soil that forms the nucleus of the North American or Laurentia craton. It is an area mostly composed of igneous rock which relates to its long volcanic history...

. Eruption of plateau lavas near the Coppermine River

Coppermine River

The Coppermine River is a river in the North Slave and Kitikmeot regions of the Northwest Territories and Nunavut in Canada. It is long. It rises in Lac de Gras, a small lake near Great Slave Lake and flows generally north to Coronation Gulf, an arm of the Arctic Ocean...

 southwest of Coronation Gulf

Coronation Gulf

Coronation Gulf lies between Victoria Island and mainland Nunavut in Canada. To the northwest it connects with Dolphin and Union Strait and thence the Beaufort Sea and Arctic Ocean; to the northeast it connects with Dease Strait and thence Queen Maud Gulf. To the southeast lies Bathurst...

 in the Arctic

Arctic

The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...

, built an extensive plateau about 1200 million years ago with an area of about 170000 square kilometre representing a volume of lavas of at least 500000 km³ (119,956.4 cu mi).