There are three main types of lava: a'a, pahoehoe and pillow lava. Each one flows at a different rate and has a different mineral composition. More »

A stratovolcano is formed from alternating sheets of lava flows and pyroclastic materials, such as volcanic ash, lapilli, volcanic bombs and cinders. This type of volcano is also referred to as a composite volcano. Examp... More »

The three types of volcanoes are shield, cinder cone and composite volcano. Volcanoes are created when heated, melted rock, magma rises to the surface of the Earth. The three types of volcanoes differ in the type of mate... More » Science Earth Science Volcanoes

One of the primary differences between pahoehoe and a'a lava formations is in terms of texture, where pahoehoe lava is smooth and viscuous while a'a lava is rough and rubbly. Pahoehoe lava also flows and cools down at a ... More »

The four types of lava are basaltic, andesitic, dacitic and rhyolitic. Basaltic is further divided into pillow, a'a and pahoehoe lava. The primary difference among these types is the amount of silica they contain. Higher... More »

Volcanoes erupt to release pressure built up in the magma chamber by expelling the magma as lava. Along with lava, a volcanic eruption releases ash and greenhouse gases such as sulfur dioxide and carbon dioxide. More » Science Earth Science Volcanoes

Cinder cone volcanoes generally spew lava dramatically when they erupt, though the eruptions are not particularly dangerous to human populations. Dramatic and beautiful as the eruptions may be, they are quite insignifica... More »