Igneous rocks that cool and solidify rapidly at or very near the Earth’s surface. Also known as volcanic rocks. .
Extrusive refers to igneous rocks that are forced out onto the Earth's surface. Volcanic ash and lava flows solidify to form extrusive rocks. More or less synonymous with volcanic.
rock an igneous rock formed at or near the earth's surface
finely crystalline or glassy igneous rock resulting from volcanic activity at or near the surface (cools very quickly!).
of rock material; forced out while molten through cracks in the earth's surface
Extrusive rocks, such as basalts, are formed when molten material from within the earth is expelled onto the surface. Because of the difference in temperature between the hot interior and relatively cool exterior of the earth, the molten materials cool rapidly. Very fine crystals, characteristic of this type of rock, form as a result of the sudden cooling.
term used to describe igneous rocks which has been erupted onto the earth's surface.
igneous rocks formed from magma issuing from volcanoes on the Earth's surface and along fissures and cracks in the ocean beds; from Medieval Latin extrusio, from Latin extrudere 'to thrust out'.
Said of lava (or the resulting igneous rock after cooling) that has been erupted onto the land surface.
igneous rock which has been erupted to the surface by volcanic activity
Igneous. Antonym of intrusive.
Produced by volcanic activity.
Extrusive refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. This is opposed to intrusive rock formation, in which magma does not reach the surface.