Ch 12 The Dynamic Planet

Earth's magnetic field A) Is variable, and it has phased to zero some nine times during the past 4 million years B) is constant in its intensity C) remain a mystery as to its cause D) is principally generated in the inner core

A) Is variable, and it has phased to zero some nine times during the past 4 million years

The oceanic crust thickness is about ___ km, and the average continental crust thickness is ___ km.

5; 30

At which of the following locations does subduction occur? A) Along collision zones between two continents B) At sea floor spreading zones C) Above mantle hot spots D) along collision zones between continental and oceanic plates

A) Along collision zones between two continents

Which of the following gives the correct sequence of layers in the mantle, from bottom to top? A) Mantle, upper mantle, asthenosphere B) Asthenosphere, mantle, upper mantle C) upper mantle, asthenosphere, mantle D) mantle, asthenosphere, upper mantle

A) Mantle, upper mantle, asthenosphere

Which of the following are located along the mid-ocean ridge? A) Volcanoes B) Outcrops of granite C) Old oceanic sediments D) None of the above

A) Volcanoes

Which of the following is an exogenic process? A) Weathering B) Volcanism C) flows of heat and materials in the mantle D) Earthquake

A) Weathering

There are two types of time, which are ____ and ____.

Absolute and relative

Which of the following lists the correct sequence of divisions in the geologic time scale, from largest to smallest? A) Era, eon, epoch, period B) eon, era, period, epoch C) epoch, era, eon, period D) period, eon, era, epoch

B) Eon, era, period, epoch

Which of the following plays a role in the shaping of the Earth's surface? A) gravity B) the action of wind, water and ice C) The radioactive decay of atoms D) all of the above E) B & C only

D) All of the above

TRUE OR FALSE: Radioactivity dating only can be used to measure relative time.

False

TRUE OR FALSE: Since the core's mass is about one third of Earth's entire mass, the volume of the core is also of one third of the Earth's entire volume

False

TRUE OR FALSE: The Moho mirrors the surface topography, i.e, high places of the surface of the Earth overlies areas in which the Moho descends to greater depth, and vice versa.

False

TRUE OR FALSE: The density of material below the Moho is less than that above it

False

TRUE OR FALSE: The oceanic crust is less dense than the continental crust.

False

The decay rate is expressed as _____, the time required for one half of the unstable atoms sample to decay into daughter isotopes.

Half life

The youngest epoch in the geologic time scale is _____.

Holocene

The geologic cycle is composed of three subsystems:_____,_____ and ______.

Hydrologic rock tectonic

The transportation and deposition of materials by media powered by solar energy is the _____ cycle.

Hydrologic cycle

Three basic rock types are _____ (fire-formed, molten), _____ (from settling out) and ______ (transformed from any other rock through extreme heat or pressure).

Igneous Sedimentary Metamorphic

The Earth's dominant materials are ___ and ____.

Iron and Silica

The principle of buoyancy and balance, when applied to Earth's crust, helps us to explain fluctuations in Earth's outer crust, a property known as

Isostatic adjustment

Wegener used _____ to name a supercontinent approximately 225 million years ago.

Pangaea

Several large, linear lakes are formed in East Africa. This is evidence of what process?

Rifting

Divergent plate boundaries are characteristics of

Sea-floor spreading centers

Two most abundant chemical elements in earth's crust are _____ and _____.

Silicon and Oxygen

When geologists or archaeologists dig downward into a unit of rock or sediment, they are digging "back in time". The fact is based on the principle of ____.

Superposition.

Heat energy and new materials are brought to the surface from interior by the _____ cycle.

Tectonic

TRUE OR FALSE: Depth of earthquake focus increases with increasing distance from ocean trench.

True

TRUE OR FALSE: Earth was once in a molten state, during which materials became sorted based on density.

True

TRUE OR FALSE: Ocean floor subducts under continents because the ocean floor is denser than continental material.

True

TRUE OR FALSE: The Hawaiian Islands were formed as a result of a rising plume of magma from the mantle.

True

TRUE OR FALSE: The age of the sea floor increases with increasing distance from a mid-ocean ridge.

True

TRUE OR FALSE: The fluid outer core generates 90% of Earth's magnetic field.

True

TRUE OR FALSE: The magnetic stripes found around mid-Atlantic ridge were due to the magnetic reversal

True

TRUE OR FALSE: Uniformitarianism assumes that the same physical processes we see today are a key to understand the processes that have been operating throughout the geologic time.

True

List 3 types of plate boundaries

divergent, convergent, transform

Knowledge of Earth's interior is derived from

indirect evidence involving the analysis of seismic waves

Which of the following statements about earth's core is not true? A) It is composed primarily of iron B) the inner core is believed to be liquid and the outer core solid C) Temperature in the core reaches several thousand degrees D) Temperatures and pressures are higher in the inner core than in the outer core

B) the inner core is believed to be liquid and the outer core solid

Which of the following is incorrectly matched? A) Endogenic-internal processes B) Exogenic-external processes C) Radioactive decay heat-exogenic energy source D) Weathering-exogenic breaking dissolving the crust

C) Radioactive decay heat-exogenic energy source

Which of the following is an endogenic process? A) Weathering B) Stream Disposition C) Volcanism D) glacial erosion

C) Volcanism

List four evidences Wegener used to prove his hypothesis

Coastal lines, fossils, rock types, and ancient climates.

Convergent plates boundaries are characteristics of

Collision zones between plates

In 1912, German geophysicist and meteorologist, Alfred Wegener first proposed the _______ hypothesis about the earth's land mass migration.

Continental drift

Which of the following gives the correct sequence of layers in the Earth, from the surface to the center? A) Crust, core, lower mantle, asthenosphere B) asthenosphere, lower mantle, crust, core C) crust, lower mantle, asthenosphere, core D) Crust, asthenosphere, lower mantle, core

D) Crust, asthenosphere, lower mantle, core

Which of the following is not an example of an age-relationship based on absolute dating? A) Oldest rocks on earth is about 4 billion yrs old B) Oldest fossil on earth is about 3.5 billion yrs old C) The dinosaurs became extinct 65 million yrs ago D) The Coconino formation in the grand canyon is older than the Kaibab formation

D) The Coconino formation in the grand canyon is older than the Kaibab formation

Which of the following is true of the asthenosphere? A) It contains pockets of increased heat B) it flows C) it carries the lithospheric plates D) all of the above E) none of the above

D) all of the above

Which layer of the planet forms 80% of earth's total volume, and has an average density of 4.5 g/cm3

mantle

The asthenosphere can be described as

plastic-like