PHS Unit 2

Today, glaciers cover approximately ________ percent of the earth's surface.

10

Desert and steppe lands cover about what percentage of Earth's land area?

30%

Earth formed approximately ________ years ago.

4,600,000,000

What is the major difference between a subduction zone and a collisional mountain chain?

A subduction zone has active volcanism.

Why is wind less effective than moving water at picking up and moving materials?

Air is less dense than water.

Visualize five horizontal undeformed sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, with 1 representing the lowest of the five beds and 5 representing the highest of the 5 beds. Which of the following statements concerning the strata is true?

Beds l and 3 are older than bed 4.

The era known as the "age of mammals" is the ________ era.

Cenozoic

Much of the city of New Orleans is below sea level, yet it was not an ocean when the city was first settled. How did it get below sea level?

Drainage canals and groundwater withdrawal produced subsidence that dropped the land below sea level.

Earth's primitive atmosphere evolved from gases ________.

Expelled from within

Why is the molten metallic outer core and the magnetic field important to life on Earth?

If we did not have the molten core and the magnetic field, we would be bombarded by cosmic rays that would strip away our atmosphere.

Many reptile groups became extinct at the close of the ________.

Mesozoic

Which era is sometimes called the "age of dinosaurs"?

Mesozoic

What condition is most necessary to build a glacier?

More snow must fall in the winter than melts in the summer.

Which American state is entirely made up of Basin and Range desert?

Nevada

The largest mass extinction in the Phanerozoic occurred in the ________.

Permian

Which one of the following represents the greatest expanse of geological time?

Precambrian

________ are the earliest life forms identified on Earth and they date back to nearly 3.5 billion years ago.

Prokaryotes

How do glaciers acquire their load of sediment?

Sediments and rocks are plucked off the ground surface at the base and sides of the glacier.

________ would have the largest capacity to naturally remove sewage pollutants.

Slightly clayey sand

The water table is ________.

a boundary between saturated rock below and unsaturated rock above

An alluvial fan ________.

a fan-shaped mass of sediment deposited at the base of a mountain front due to an abrupt change in stream gradient

Which one of the following applies to a valley glacier that lengthens (extends the position of its terminus downslope over a period of many years?

accumulation exceeds wastage

Which of the following is associated with areas of karst topography?

all of these

Paleontology is the study of ________.

ancient life

Permeable rock strata or sediment that transmit groundwater freely are called ________.

aquifers

Glaciation has been recorded ________.

at multiple times throughout Earth's history

The slight eastward slope of the Great Plains was created during the Cenozoic by ________.

deposition of sediments shed from the eroding Rocky Mountains

Most active faults pose a risk to society because they can potentially produce ________.

earthquakes

The subdivision of the geologic time scale that represents the longest time span is called a(n) ________.

eon

Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time beginning with the longest time interval and ending with the shortest?

eon, era, period, epoch

The main process that links water in the atmosphere with water on Earth's surface is ________.

evaporation

The Sierra Nevada Mountains of California, and the Teton Mountains of Wyoming, ranges are examples of ________.

fault blocks uplifted by late Tertiary to Quaternary normal faulting

At the start of the Paleozoic, North America ________.

had no plants or animals

The principle of lateral continuity proposes that sedimentary rock layers continue in all directions until they grade into a different rock type or thin out on the edge of a basin is important because ________.

it allowed geologists to correlate sedimentary rock units over large distances

The principle of cross-cutting relationships which states that a geologic feature that cuts across another feature must be younger than the feature it cuts is important because ________.

it provided a tool for sorting out the relative timing of various geologic events

The principle of horizontality which states that sediments are usually deposited in relatively flat layers is important because ________.

it provided a way to recognize if rocks had been deformed

The principle of superposition which states that in undeformed rocks, the younger rocks will be on top of older rocks, is particularly important because ________.

it provided an order for assembling the relative ages of various rock layers

The Cenozoic era is often called the "age of ________."

mammals

The dominant life forms during the Cenozoic Era were ________.

mammals and angiosperms

Orogenesis refers to the formation of ________.

mountains

Which of the following features characterize meandering streams and valleys?

natural levees; broad floodplains

The Goldilocks scenario suggests that ________.

we are very fortunate to be in the right place in the universe and to have had the right condition to develop and sustain life

Glacial sediments or tills are characterized by ________.

wide variations in sizes of clasts

People learned by trial and error years ago how to paddle a canoe upstream in meandering rivers, knowing where the strongest currents were located. Assuming you don't want to go backwards, what is the best paddling route to maximize your speed upstream?

Stay on the inside bend of meanders, crossing over whenever the meander turns so you can stay on the inside bend.

In the canyonlands of Utah and Arizona, canyon walls often support "hanging gardens" in which plants cling to sandstone cliffs and these hanging gardens are typically along shale beds in the sandstone. Why is this happening in a desert setting?

The shales trap groundwater along the shale horizons that helps aid plant growth.

he Appalachian Mountains may have once been as lofty as the Himalayan-Tibetan Mountain belt is today. Why are they not this high now?

They formed long ago, and erosion has beveled them to their present low elevation.

A major difference between Catastrophism and Uniformitarianism is ________.

catastrophism supports rapid changes on the earth and a young age of Earth while Uniformitarianism requires long times for changes to be significant and thus a very old earth

The Appalachians were formed by three phases of ________ orogeny.

collisional

In the late 1800's various principles (original horizontality, inclusions, cross cutting relations, etc. arête) were established and used to ________.

organize the order in which events occurred on Earth

The waste gas released by plants as they synthesize food sugars from carbon dioxide and water is ________.

oxygen

What is the modern theory for orogenesis (mountain building)?

plate tectonics theory

About 88 percent of geologic time is represented by the time span called the ________ era.

precambrian

Climatologists define a "dry climate" as a climate in which ________.

precipitation is less than expected evaporation

The ________ is the idea or concept that ancient life forms succeeded each other in a definite, evolutionary pattern and that the contained assemblage of fossils can determine geologic ages of strata.

principle of fossil succession

The San Andreas Fault in California and the Alpine Fault in New Zealand are examples of ________.

strike-slip faults

Island arcs and Andean type mountains are both examples of mountains formed by ________.

subduction

Which of the following did not exist prior to the Quaternary Ice ages?

the Great Lakes

In the early history of Earth, the solid surface of the earth weathered more rapidly than now because ________.

the early rain was very acidic

The Colorado River still has water after it leaves the desert southwest region and enters the Gulf of California because ________.

the river began outside the desert, which is normally the only way streams that leave the desert will still have water in them

Unconformities that represent a break in the geologic record of deposition are geologically significant ________.

they represent a period of erosion in the region

Mountain building uplifts rocks against the force of gravity raising their potential energy, which requires work by the earth system. Based on the relative motion of fault blocks, what type of fault would you expect to require more energy than the others?

thrust

One of the primary goals of geology is to ________.

understand the history of Earth

Milankovitch cycles refer to ________.

variations in the earth's orbit about the sun and precession of the earth's axis

As stream discharge increases ________.

velocity, width, and depth increase

Water plays an important role in sculpting the landscape of continents because ________.

water is a major cause of erosion on land