These types of igneous rocks form outside the volcano, where it's cold. They form quickly and have small crystals.
What are extrusive rocks?
100
This is the volcano formed from felsic rock. It is a pile of rocks.
What is a cinder cone?
100
This is what remains of a volcano once all the walls have eroded and all that's left is the lava that was in the central pipe of the volcano.
What is a volcanic neck?
100
This is a foreign rock which falls from the walls of the magma chamber into the magma chamber.
What is a xenolith?
200
This igneous rock forms when lava cools under water, so it cools very quickly.
What is glass?
200
This igneous rock is dark, hot, has high density, flows like water and has calm eruptions.
What is mafic lava?
200
This is created by ultra-viscous lava that forms enormous sheets, burying the previous landscape.
What is a flood basalt?
200
This is a small mount of lava in the crater at the top of the volcano which slowly pushes up out of the crater.
What is a lava dome?
300
This is a source of pressure in volcanoes. It also results in the distinctive feature of vesicular rocks.
What is gas?
300
This is typically a coastal volcano with alternating layers of mafic and felsic rock. It has very steep sides.
What is a stratovolcano / composite volcano?
300
This is formed when the land on top of an empty magma chamber falls into the magma chamber. Crater lake is an example of this.
What is a caldera?
300
This is when lava enters and cools in a horizontal crack in a rock.
What is a sill?
400
This is qualified as an extrusive rock, although it cooled partially inside and partially outside the volcano, resulting in both large and small crystals.
What is porphyry?
400
This is the largest type of volcano. It forms from mafic magma and is generally found in the ocean.
What is a shield volcano?
400
This is formed when the outside of a lava flow hardens, but the inside does not, leaving a hollow cavern.
What is a lava tube?
400
This is when lava enters a horizontal crack in a rock, then forms a bubble underground in this crack. This results in a dome on the ground from the overlying rocks being pushed upwards.
What is a laccolith?
500
This igneous rock forms from hot magma inside a volcano. Since it cools slowly, large crystals form.
What is intrusive rock?
500
This rock is light in colour, cold, has low density, lots of gas, the consistency of bread dough and violent eruptions.
What is felsic?
500
This is formed when a magma chamber cools and rises to the surface, forming large mountains.
What is a batholith?
500
This is when lava enters a vertical crack in the ground.