Igneous Rocks and Volcanic Processes

Flashcards about Igneous Rocks and Volcanic Processes

What is lava?

Magma that reaches the surface of the Earth.

How does silica content affect magma?

Magma with more silica is generally thicker and stickier.

Where are volcanoes commonly found?

Divergent and convergent plate boundaries, and hot spots.

What are the main types of volcanoes?

Shield, composite, and cinder cone volcanoes.

Describe a shield volcano.

Wide and low, formed from runny lava flows.

Describe a composite volcano.

Steep and layered, made of lava and ash.

Describe a cinder cone volcano.

Small and made from lava fragments.

What are fissure eruptions?

Lava flows through cracks in the Earth's surface.

What is columnar basalt?

Cooled lava that fractures into hexagonal columns.

What are the different sizes of pyroclasts?

Ash, lapilli, bombs, and blocks.

What is volcanic ash?

Small rock pieces thrown out by explosive eruptions.

What are pyroclastic flows?

Fast, hot, and heavy flows of gas and volcanic matter that move down valleys.

What are pyroclastic surges?

Cooler and faster-moving flows that can travel uphill.

What are lahars?

Mudflows composed of ash and water.

What causes rocks to melt and form magma?

Heating above melting point, pressure dropping, and presence of water.

What explains the order in which minerals form as magma cools?

Bowen's Reaction Series.

What types of rocks are associated with mafic, intermediate, and felsic magma?

Mafic: Basalt, Intermediate: Andesite, Felsic: Rhyolite

What are the two main ways igneous rocks form?

Intrusive (cools inside Earth) and Extrusive (cools on surface).

What are the different types of textures found in igneous rocks?

Aphanitic, Phaneritic, Porphyritic, Vesicular, Glassy, Pyroclastic, and Pegmatitic.

How can we reduce volcanic hazard risks?

Prediction, early warning, engineering, monitoring, and understanding past eruptions.