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
