Igneous rock as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, or without crystallization to form natural glasses. Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earth's crust by volume. Igneous rocks form about 15% of the Earth's current land surface. Most of the Earth's oceanic crust is made of igneous rock. Igneous rocks are also geologically important because: In terms of modes of occurrence, igneous rocks can be either intrusive (plutonic and hypabyssal) or extrusive (volcanic). Intrusive igneous rocks are formed from magma that cools and solidifies within the crust
Potrillo volcanic field are five maars in the Potrillo volcanic field. A cinder cone also known as scoria cone, is a steep, conical hill formed on top of a vent. The cinder cones often occur in groups usually on the sides and around the shield volcanoes and the strato volcanoes. They are formed form lava fragments called cinders, it is magma that is glassy and has hundreds of gas bubbles that are frozen, it cools quickly after it is ejected into the air. The lava is expelled from the vent and formed around the vent when they fall back after it is ejected.