sentence: Blocky lava is so thick and slow that it barely moves along the ground.
sentences_before: Lava' is magma that flows onto the Earth's surface.
sentences_after: Other types of lava, like 'pahoehoe', 'aa', and 'pillow lava', are thinner and flow faster.
concept_name: blocky lava
headings: Lava
categories: Volcanology