GMU Geology 101 Exam 2

What statement best describes erosion?

the process by which weathered rock and mineral particles are removed from one area and transported elsewhere

In correct order from the center outward, Earth includes which layers?

inner core, outer core, mantle, crust

Which kind of volcanism is typical of mid-oceanic ridge systems?

submarine; basaltic lava flows

What statement concerning earthquake foci and epicenters is correct?

The epicenter is at the surface directly above the focus where the earthquake initiates

A stream begins at an elevation of 3 km and flows a distance of 100 kilometers to the ocean. What is the average gradient?

0.03

What two chemical constituents CANNOT form by chemical weathering of the feldspar minerals?

iron oxides and magnesium bicarbonates

Which combination would result in a magma with the highest viscosity

high silica, cool temperature, less dissolved gasses

What best describes volcanism in the Cascade Range, northwestern United States?

related to plate subduction

What can S and P waves travel through?

S waves travel through solids and P waves travel through liquids and solids

Dense forms of ________ are probably major components of the inner core

liquid iron-nickel-sulfur alloy

Which mass wasting events is most likely to triggered by an earthquake?

Slump

The top of the asthenosphere is closest to Earth's surface________

Along a mid-ocean ridge

The ________ describes the movement of water through Earth's hydrosphere

Hydrologic Cycle

________ are caused by displacement of ocean water by motion along an underwater plate boundary

Tsunami

________ are associated with a mid-ocean ridge

submarine basaltic lava eruptions, very thin ocean floor sediment layer, shallower depths than abyssal plains

What is the ultimate base level for all streams?

Sea Level

A transform fault is ________

a strike-slip fault that forms the boundary between tectonic plates or portions of plates

What is true of deep ocean trenches?

Sites where plates plunge back into the mantle, geologically stable, they are sediment traps

From the land surface downward to the unweathered bedrock, which of the following is the correct order of the different soil horizons?

O, A, E, B, C, bedrock

Where is erosion concentrated along a meandering stream?

On the outerparts of the meander loops or bends

What is true for anticlines but not for synclines?

The deeper strata are buckled upward along the fold axis

The ________ is a direct measure of the distance from a seismic receiving station to the focus of a distant earthquake

time interval betwen the first P and S- wave arrivals

A(n)________ is a thick accumulation of sediments and small, tectonic blocks formed of material scraped off a descending, lithospheric plate

Accretionary- wedge complex

All of the following are layers that comprise oceanic crust (an ophiolite complex)

Deep sea sediment, basaltic lava pillows, sheeted dike complex, gabbro, peridotite

What is not true about soils?

All soils include all of the named soil horizons

Brittle deformation would be favored over plastic deformation in which of the following conditions?

cooler temperatures

What is the drop in water surface elevation divided by the distance the water flows?

Hydraulic Gradient

_______ is the process by which rocks break down into smaller pieces or become chemically altered at or near the earth's surface

Weathering

What are the three components of magma?

solid, liquid, gas

_______ refers to the "bouncing" mode of sand transport in a windstorm or stream

Saltation

New oceanic crust is forming at the _______

Oceanic ridges

The gently sloping submerged surface extending from the shoreline toward the deep ocean is termed the ________.

Continental Shelf

Seamounts

are sumberged volcanoes that form on the ocean floor

What is the angle of repose?

the slope at which unconsolidated particles assume a stable slope

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

Pahoehoe

Natural levees form when...

streams flood and drop sediment just outside their normal channel

What causes the most damage during earthquakes?

S Waves

A ________ volcano is a large, gently sloping mound composed of basaltic lava flows

Shield

Which kind of eruptive activity is most likely to be highly explosive?

Eruptions of big, continental margin, composite cones.

Under similar warm, moist climatic conditions, why would basalt and gabbro generally have higher chemical weathering rates than rhyolite and granite?

The iron and magnesium rich minerals in the gabbro and basalt are subject to chemical breakdown at earth's surface conditions

Deep-focus earthquakes, those between 300 and 700 kilometers below the surface, occur only in association with _______

Subduction zones

What is a Lahar?

A mass wasting event composed of volcanic ash and water

Oceanic ridges are elevated compared to the surrounding ocean floor because ________

newly formed lithosphere is hotter and therefore less dense than the surrounding rocks