Basaltic lava and the different types of lava flows Basalt is one of the most common types of rock in the Earth's crust, according to USGS, and makes up most of the ocean floor.

Volcanoes are grouped into four types: cinder cones, composite volcanoes, shield volcanoes and lava volcanoes. Cinder cones are circular or oval cones made up of small fragments of lava from a ...

Lava flows are outpourings of molten rock on the earth's surface. They're very common in volcanic eruptions, and they come in different forms: pahoehoe an a'a.

Hawaii volcanoes are known for two main types of lava flows. The first, called a'a, is generally characterized by lava that flows fast and cools quickly, creating a jagged, rough surface.

This type of lava can get very hot, but it’s so liquid-like that any gas just bubbles out of it. “It creates more gentle eruptions and these beautiful, dome-shaped volcanoes,” says McKinnon.

So what caused the explosion that rained down rocks and rubble onto a crowded tour boat on Monday? The U.S. Geological Survey calls the event a littoral explosion.

Lava flows are very common in volcanic eruptions, and they come in different forms like pahoehoe an a'a.

Lava flows are very common in volcanic eruptions, and they come in different forms like pahoehoe an a'a.

Lava flows are very common in volcanic eruptions, and they come in different forms like pahoehoe an a'a.