Volcanology

unique identifier for a volcano or related feature

geologic distinction in the Pacific Ocean

igneous rocks which have a deficiency of aluminium

small enclosed cavity found in some volcanic rock, such as basalt

dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it

volcano in Rio de Janeiro, Brazil

bands or layers that can sometimes be seen in rock that formed from magma

deposit of material ejected from a volcanic eruption

group of polygenetic volcanoes

award for research in volcanology

circular igneous intrusion

thumb|A lithophysa from France thumb|A collection of lithophysae "thundereggs" A lithophysa (plural lithophysae, from Greek lithos "stone" + phusa "bubble") is a felsic volcanic rock with a spherulitic structure and interior cavity with concentric chambers. Its outer shape is spherical or lenticular. They vary in size from very small up to twelve feet in diameter depending on the age of the magma chamber. These rocks are usually found within obsidian or rhyolite lava flows. Lavas low in feldspar minerals may produce a version known as snowflake obsidian.