Geology

Because earth is a closed system, which of the following statements is NOT true? -Actually, all of the statements listed here are true -Earth freely gains energy from the sun and loses energy to space -All waste and pollutants generated on Earth stay on Earth -Gains and loses of matter are negligible -There is a finite supply of resources

-Actually, all of the statements listed here are true

Which statement about differences between continental and oceanic crust is NOT true? -Continental crust is older -Continental crust is higher in Na and K -Continental crust is lower in Fe and Mg -Continental crust is denser -Continental crust is thicker

-Continental crust is denser

Earth's interior is hot for all of the following reasons EXCEPT -Earth's interior is mostly magma -formation of the Earth by accretion generated huge amounts of heat, from which the Earth is still cooling off -actually, earth's interior is hot for all of the reasons listed here -radioactive decay of unstable elements in the earth is a process that releases heat

-Earth's interior is mostly magma

In terms of volume, most of the Earth consists of the -Mantle -Asthenosphere -Crust -Lithosphere -Core

-Mantle

The layer of the Earth that is thought to be a liquid is the: -Inner core -Outer core -Crust -Mesosphere -Mantle

-Outer core

Buoyant materials are added to the edge of continents by: -Seafloor spreading -Subduction of the surrounding oceanic crust -Continental rifting -Erosion and sedimentation

-Subduction of the surrounding oceanic crust

What is the relationship between the crust and lithosphere? -The lithosphere is synonymous with the crust -the crust is made of light silicates, while the lithosphere is made of heavy silicates -The lithosphere includes both the crust and the uppermost mantle -The lithosphere is rigid, while the crust is soft

-The lithosphere includes both the crust and the uppermost mantle

The process by which the planets, including Earth, were formed by gravitational attraction of matter is called -collision -accretion -coalescence -differentiation

-accretion

A hotspot is -a strongly magnetic section of sea floor -an area of unusually strong earthquakes -a place where sea floor is destroyed -an area of deep mantle upwelling that is independent of plate boundaries

-an area of deep mantle upwelling that is independent of plate boundaries

Differentiation of Earth's interior into different layers was caused by differences in -pressure -density -temperature -age

-density

Tectonic plates of rigid and brittle __________ move over a softer and ductile ___________ below. -asthenosphere, lithosphere -mantle, crust -crust, mantle -lithosphere, asthenosphere

-lithosphere, asthenosphere

Which choice best describes the age distribution of oceanic crust? -oceanic crust is older on one side of the ridge and younger on the other -oceanic crust is youngest at the ridge and gets older with increasing distance from the ridge -there is no orderly distribution to the age of oceanic crust -oceanic crust is oldest at the ridge and gets younger with increasing distance from the ridge

-oceanic crust is youngest at the ridge and gets older with increasing distance from the ridge

How did seafloor spreading revive Alfred Wegener's ideas about continental drift? -sea floor spreading relied on new fossil evidence documenting the former joining of the continents -sea floor spreading provided a viable mechanism for moving the continents -sea floor spreading provided an explanation for the consumption of oceanic crust at plate boundaries -the topography of the ocean floor demonstrated that mountain ranges on either side of the Atlantic Ocean were formerly joined -sea floor spreading provided proof of plate tectonics

-sea floor spreading provided a viable mechanism for moving the continents

Subduction zones were discovered when -when it was noticed that deep earthquakes are found only near ocean trenches, and that earthquakes increase in depth with distance from the trench -when no old oceanic crust could be found anywhere -deep trenches on the ocean floor were mapped -when it was noticed that magnetic reversals occur periodically

-when it was noticed that deep earthquakes are found only near ocean trenches, and that earthquakes increase in depth with distance from the trench

The division of Earth's interior into core, mantle, and crust is used to describe differences in -Composition -Physical state and behavior -Temperature -Age

Composition

How did the discovery of magnetic reversals confirm the sea floor spreading hypothesis?

Magnetic reversals are the periodic change in the orientation of earth's magnetic field. The magnetic field occasionally flips polarity. When rocks containing iron minerals crystallize from lava, the iron mineral crystals align themselves with the polarity of the ambient magnetic field at the time of crystallization. This orientation is locked in place and will not change. When the seafloor was mapped in detail, it was discovered that the oceanic exhibits "stripes" of normally and reversely magnetized rocks that are symmetric on either side of the mid-ocean ridge system. Rocks at the ridge axis today show normally polarity, and then as you move away from the ridge on either side you enter a belt of reversely magnetized rocks. This pattern indicates that rocks along the ridge today formed in today's interval of normal polarity. Rocks in reversely magnetized belt formed in the last period of reserved polarity, and then moved away from the ridge due to seafloor spreading.

Describe the Earth's structure in terms of both chemical composition and physical properties

The earth is divided into three layers, a crust, a mantle and a core, that differ in their chemical composition. The crust is the thin outer layer. It is then divided into continental and oceanic crust. The oceanic crust is thinner and denser.The continental crust is thicker and less dense. The mantle is made of magnesium, iron, and silicon. The core is almost all iron and nickel. The outer core is liquid iron and the inner core is solid iron. The mantle and crust are then divided into the lithosphere, asthenosphere, and mesosphere, depending on their physical properties.The lithosphere includes the crust and uppermost part of the mantle where rocks are way below their melting point. Further down in the mantle is the asthenosphere where rocks are weak.The deepest part of the mantle is the mesosphere.

Explain why geologists believe that the Earth's core is made mostly of iron

The magnetic field shows core must be metallic and at least part molten as well as the total mass and average density of earth known from the strength of its gravitational field. Also, meteorites which have leftover accretionary material show that there are common elements in the solar system. And, iron with a small amount of nickel are abundant in meteorites and provides needed density.

Identify the three types of plate boundaries and describe the major geologic and tectonic processes occurring at each.

The three types are convergent, divergent and transform. At convergent, two plates are colliding with each other. This causes subduction and destruction of old oceanic crust, volcanism as well as earthquakes. Divergent plate boundaries are when two plates are moving away from each other. This causes the magma from the mantle to rise and cause new oceanic crust. Lastly, at transform plate boundaries, two plates are sliding past one another in different directions. Earthquakes do/can occur during this.