Exam 4: Volcanism and Extrusive Rocks

Most of the better known composite volcanoes on Earth are __.

Composite volcanoes are also called cinder cone volcanoes.

Volcanic domes are steep-sided domes or spine-shaped masses of volcanic rock formed from viscous lava that solidifies in or immediately above a volcano's vent.

Rhyolite is a fine-grained extrusive rock composed of feldspar with some quartz.

A _________ is a volcanic depression much larger than the original crater, formed when the volcano collapses into a vacated magma chamber.

The eruption of ______ is related to the fact that the North American plate is overriding a portion of the Pacific Ocean floor.

_________ crystallizes from an intermediate composition lava.

Basalt is a variety of gabbro.

The more _____ the lava, and the greater the amount of gas trying to escape, the more violent the eruption.

A _____ volcano is composed of alternating layers of pyroclastic fragments and solidified lava flows.

Shield volcanoes have ___ bases and ___ inclined slopes.

The most common mafic volcanic rock is __.

Because _____ magmas are the most viscous they are associated with the most violent eruptions.

Radar images of which planet show a surface that is young and still volcanically active?

Silicic lavas, which are relatively high in silica, tend to be more fluid than mafic magmas.

A(n) _______ is a mix of gas and dust emitted by a volcano that is so dense that it hugs the ground.

Weathered volcanic ash and lava produce excellent fertile soils.

________ is a rock composed of fine-grained pyroclastic particles.

The original volcano Mount Mazama erupted to form Crater Lake, Oregon.

The term ___ is used for molten rock on the Earth's surface.