Life and Earth's Crust

Rheology is best described as the study of _______. a. the flow of matter b. the Earth's crust c. magma d. the Earth's core

A.

The continental crust covers _______ of the Earth's surface. a. 40% b. 50% c. 60% d. 70%

A.

The Earth's crust is principally composed of _______. a. granitic and sedimentary minerals b. granitic and basaltic minerals c. basaltic and sedimentary minerals d. none of the above

B.

Explain how biogeochemical cycles and the rock cycle are important for life on Earth.

Biogeochemical cycles and the rock cycle allow nutrients to be recycled through the abiotic and biotic zones of Earth. They are responsible for the cycling of oxygen, carbon dioxide, phosphorus and nitrogen between the biosphere and the rest of Earth

The core of the Earth is mostly composed of _______. a. magnesium and silicon b. aluminum and silicon c. nickel and iron d. aluminum and iron

C.

Which of the following best describes the compositional layers of the earth? a. All layers of the Earth below the crust are liquid. b. The only liquid layer of the earth is the mantle. c. The crust floats on top of the outer core. d. Some layers of the earth are liquid, and some are solid.

D.

Explain what differentiates the Earth's crust and lithosphere.

Earth's crust is distinguished from the lithosphere because the crust refers to a compositional later and the lithosphere is a mechanical layer, the solid layer near the surface of the Earth. The crust is mostly composed of alumino-silicate minerals while the lithosphere includes some of the solid regions of the upper mantle which is mostly ferro-magnesium silicates.

Explain how fossil fuels found in the Earth's crust are ultimately the result of biological processes.

Fossil fuels are formed when organic matter such as the remains of animals and plants are buried and sequestered deep underground. The energy stored in these once-living things, as well as the process of being buried, causes the organic material to undergo a series of chemical transformations.

Explain how oceanic crust is continuously created at mid-ocean ridges.

Mid-ocean ridges are geologically active, and as magma emerges on the ocean floor at these points it crystallizes to form basalt. As the deposits of basalt build up, the continental plates separate and this slab pull moves this new basaltic crust away from the mid-ocean ridge.

Explain how ocean ridges and trenches are formed.

The upwelling of magma from the asthenosphere pushes on thin regions of oceanic crust, causing them to thicken and move upward, forming ridges. Gravity and slab pull in the Earth's tectonic plates then pull down on the ridge and the material in the ridge spreads out across the ocean floor. When slab pull drags one edge of a tectonic plate under another it creates an oceanic trench.