sentence: Shield volcanoes can produce huge areas of basalt, which is usually what lava is when cooled.
sentences_before: Because the lava is so fluid, it spreads out, often over a wide area. Shield volcanoes do not grow to a great height, and the layers of lava spread out to give the volcano gently sloping sides.
concept_name: shield volcano
headings: Volcano Types of volcanoes Shield volcanoes