Chapter 14

What are the four basic types of volcanoes and their characteristics?

1- Composite cone - consist of a mix of lava flows and pyroclastic materials 2- Shield volcano - composed of lavas and relatively little ash or cinders and gentle slopes 3- Plug domes - extrude extremely stiff acidic lava that fills the initial pyroclasitc cone and steep sided 4- Cinder cones - smallest type, produces litle lava and consists largely of pyroclastics

The Alaskan earthquake of 1964 was extraordinarily violent and has been assigned a moment magnitude of ________.

9.2

Presently, the North American and Eurasian plates are moving ________.

Away from each other

The ________ is an igneous intrusion which has a surface area of at least 100 square kilometers.

Batholith

The most massive form of igneous intrusion is a ________.

Bathroom

Crater Lake, Oregon, is an example of a volcanic ________.

Caldera

Radial walls extending outward from a volcano are ________.

Dikes

A(n) ________ is an abrupt movement of the Earth's crust usually associated with a fault zone.

Earthquake

A fault is any break in the Earth's surface or crust.

False

Prior to Mt. St. Helens in 1980 there had never been an active volcano in the United States.

False

Lava flows often create ________.

Flattish Plains

What is the difference between "folding" and "faulting?"

Folding is the wrinkling of the earth's surface from slow lateral compression.Faulting is the rupture or breaking of the earth's surface from faster process.

A crustal block which is downthrown with a steep fault scarp on either side is a ________.

Graben

Grabens are commonly found in association with ________.

Horsts

A volcanic mudflow is known as a(n) ________.

Lahar

Currently, the rate of sea-floor spreading in the Atlantic is thought to be

Less than 1 centimeter per year

A ________ is a one-sided fold connecting horizontal or gently inclined strate.

Monocline

Volcanic activity that takes place deep under the crust is termed ________.

Plutonic

The totality of materials ejected from a volcano, including liquid material, ashes and dust is termed ________.

Pyroclastic Material

A lengthy complex of grabens forms a ________ valley.

Rift

Water collected in small bodies along a recently active fault line forms ________.

Sag Ponds

Similar in nature to a batholith but much smaller in size is a ________.

Stock

Instead of the vertical displacement of other faults, a ________ fault has horizontal displacement .between the two sides

Strike-Slip

________ is an area of extensive flood basalts.

The Columbia Plateau or The Deccan Plateau

Relatively cooler magma in an erupting volcano is apparently the result of ________.

The relatively high amount of silica present

A ________ plate boundary is associated with lateral slippage, conservation of existing crust, and the San Andreas fault system?

Transform

A foreshock sometimes comes before a major earthquake.

True

A simple symmetrical upfold in topography is an anticline.

True

Deep fault zones apparently serve as conduits allowing water and heat to approach the surface.

True

In the Cascade Range, there are many peaks larger or taller than Mount Saint Helens which exploded.

True

The Andesite Line refers to the numerous volcanoes which dot the rim of the Pacific Ocean.

True

The Earth's crust is rigid as compared to the mantle directly underneath.

True

The largest recorded earthquake had a moment magnitude of 9.5 and occurred in Chile.

True

The southern portion of the "super continent" envisioned by Wegener is called Gondwanaland.

True

On the Modified Mercalli scale, the largest earthquakes would be assigned a value of ________.

XII

In earthquakes, P waves________.

are faster than S waves

Mt. St. Helen's is ________.

likely to vigorously erupt again