Week 2 Homework

What is the difference between a dike and a sill?

A dike intrudes across sedimentary layers, and a sill intrudes between sedimentary layers

Has a rough, broken surface. It is caused by rapidly moving basalt that cools quickly. What type of lava flow is this?

AA Flow

A magnifying glass or microscope is needed to see individual mineral grains. What type of texture does this rock have?

Aphanitic

Broad sheets of what kind of lava flow travel long distances and give shield volcanoes their distinctive shape?

Basaltic lava

What is a magma chamber called after the conduit has solidified and been exposed by erosion?

Batholith

Has a rough surface composed of smooth-sided fragments. It is formed by viscous lava cooling quickly. What type of lava?

Block lava

What kind of volcano is very steep-sided and built primarily from ejected lava fragments?

Cinder cone

What type of volcano has a crater at the summit and steep flanks?

Cinder cone

What type of volcano is Paricutin in Mexico?

Cinder cone

What type of volcano is San Francisco Peaks in Arizona?

Cinder cone

What type of volcano is known for reddish-brown lapilli?

Cinder cone

What kind of volcano has broad and moderately steep flanks and a steep summit, results from the eruption of a mixture of both lava flows and pyroclastic deposits that contain less fluid materials and travel shorter distances?

Composite

What type of volcano has a steep summit and broad, moderately steep flanks?

Composite

What type of volcano is Cotopaxi in Ecuador?

Composite

What type of volcano is Fujiyama in Japan?

Composite

What type of volcano is Mt. St. Helens in Washington?

Composite

What type of volcano is known for erupting lava and pyroclastic material?

Composite

What are some intrusive igneous rocks?

Diorite Granite

Match the following rocks to their equivalent aphanitic or phaneritic igneous rocks... Andesite --> Rhyolite --> Gabbro -->

Diorite Granite Basalt

Magma cools and consolidates without growth of mineral grains. What type of texture does this rock have?

Glassy

Name a characteristic of Andesitic composition

Intermediate lava flow

Why does magma have a tendency to rise after its formation?

It is less dense than the surrounding rock

Name three characteristics of Basaltic composition

Lava flows in sheets Fast lava flow 90% of lava on Earth

What results from a relatively fluid cooling and forming an outer shell. The lava continues to flow inside the outer shell.

Lava tube

What lies underneath volcanic features at Earth's surface?

Magma chambers and volcanic conduits

Has a smooth, billowy surface. It is caused by slowly moving basalt that is still hot. What type of lava flow is this?

Pahoehoe Flow

Mineral grains are of roughly equal size and coarse enough to be seen without a magnifying glass or microscope. What type of texture does this rock have?

Phaneritic

What kind of lava is composed of solid, bubble-like masses and is caused by extremely quick lava quenching?

Pillow lava

Rock has two or more distinctly different-sized populations of mineral grains. What type of texture does this rock have?

Porphyritic

What are some porphyritic igneous rocks?

Porphyritic andesite

Explosive eruptions of what create steep-sided cinder cone volcanoes?

Pyroclastic materials

What are some extrusive igneous rocks?

Rhyolite

What kind of volcano is wide that produces mainly basaltic lava flows?

Shield

What type of volcano has very broad slopes and a caldera?

Shield

What type of volcano is Mauna Loa in Hawaii?

Shield

What type of volcano is known for long lava flows and lava tubes?

Shield

Name three characteristics of Rhyolitic composition

Silica-rich lava Slow lava flow 1% of lava on Earth

Lava flows are typically finer grained than intrusive igneous rocks. Why?

The extrusive magma cools quickly so the mineral grains do not have time to grow.

Most igneous rocks never reach the surface. However, igneous rocks other than those formed in volcanoes are found exposed on many parts of Earth. How do you account for this phenomenon?

They formed at depth and have been exposed by uplift and erosion.

Why are volcanic rocks often exposed at Earth's surface as hills, ridges, and mountains surrounded by areas of lower elevation?

Volcanic rocks are often more resistant to erosion than surrounding rock

Moderately viscous and gas-rich ________ lavas can erupt as lava flows or pyroclastic materials, leading to the steepening slope of composite volcanoes.

andesitic

Pyroclastic debris from a volcanic eruption can include what 2 things?

ash and cinders

When lava erupts at Earth's surface, what type of rock is produced?

extrusive

As a result of partial metaling, where does magma originate in?

the mantle and crust

What is a volcanic conduit called after the conduit has solidified and been exposed by erosion?

volcanic neck