Exam 7: Volcanoes and Other Igneous Activity

The Year Without A Summer (1816)was triggered by ________.

Which one of the following shows the correct order (from left to right)of decreasing magma viscosity? (remember that viscosity is resistance to flow, so you should pick the answer that has the most viscous lava type on the left, and the least viscous (most runny)on the right.

Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface?

You are a field geologist, dropped off in a new area. You examine the rocks of this area and find rhyolite, welded tuff, and scattered pumice. All are very young. You begin mapping the area, and soon have a rough sense of the distribution of rock units, as shown here: Note that the welded tuff varies systematically in its thickness, and that a lake is present near the center of your mapping area. How do you interpret this pattern?

Ash and lapilli are different sized pyroclastic particles.

In magma, dissolved gases make up less than 10% of its weight.

Magma generation almost always involves partial melting, not complete melting of the source rock.

The recent volcanic activity in Yellowstone National Park is caused by ________.

Which of the following best describes Shiprock, a famous volcanic feature in New Mexico?

Magma tends to rise toward Earth's surface principally because ________.

Water vapor is the most abundant gaseous component dissolved in most magmas.

When mantle peridotite partially melts beneath an oceanic ridge, ________ magma is produced.

________ tend to increase the explosive potential of a magma body beneath a volcano by the greatest amount.

What kind of volcano is pictured here?

________ are pyroclastic materials that are larger than ash, but smaller than blocks or bombs.

Mauna Loa, a volcano in Hawaii, is an excellent example of a ________.

A long-lived magma source located in the mantle is called a ________.

A high viscosity means that a lava is very fluid or runny.

Volcanoes are generally not preserved in the geologic rock record as they are eroded away. However, the various materials erupted from volcanoes are often found preserved in the rock record. How could you infer what type of volcano erupted in a given area based on the type of volcanic deposits now found as layers of rock? Give specific examples and briefly discuss if some materials may be linked to different types of volcanoes.