Extrusive Rocks


Also found in: Dictionary, Thesaurus.

Extrusive Rocks

 

(or effusive rocks), igneous rocks which, like modern lavas, poured out onto the surface of the earth through volcanic vents or cracks in the earth’s crust and solidified in the form of flows, sheets, and domes.

References in periodicals archive ?
It is worth mentioning that, according to the geophysical data, extrusive rocks forming the Deecan Plateau of India (famous for zeolites and associated minerals) are related to another hotspot active in the same region (but genetically younger at ~67 million years)--the Reunion Hotspot.
The oldest extrusive rocks are capped by a Quaternary basalt flow several hundred feet thick.