PHS 111 - 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

Use the figure below to answer the following questions. Photograph shows rock layers with some rounded folds and a line that offsets some of the folds. Letter A is in a fold shaped like a "U", letter "B" in flat lying strata, letter "C" is along the line of offset, and letter "D" is on the upturned limb of a fold. Which letter in the figure above corresponds to a "syncline"?

A

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.

Farmer Brown lives in a semi-arid part of the United States with numerous small lakes associated with glacial deposits of sand and gravel. He decides he needs to irrigate part of his land and drills a shallow well 100m from his property line with Farmer Smith who has a small lake just across the property line, and he depends on this lake to water his cattle. By late summer, Farmer Smith goes out to his lake and discovers it is dry. What happened?

Farmer Browns well has dropped the water table in the well's cone of depression, and the well has led to the lake drying up.

________ is the basic force that moves or accelerates soil and regolith down a slope.

Gravity

Note the picture below from a desert setting: Image shows a large tuft grass sitting atop a sandy hill several feet high. The hill sits about two feet above a sandy plateau and is dominated by the grasses. A man stands next to the tuft of grass for scale, indicating it is about five or six feet high. What is illustrated in the photograph?

How effective vegetation is at anchoring sediment.

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.

Below is an image of two tombstones that were both emplaced in 1863. Two images of tombstones are pictured. The left image shows almost no weathering while the right image is well weathered and some of the lettering is becoming difficult to read. Why would the left tombstone be so much better preserved that the right tombstone?

It is possible that they are both in different climates and are made of different rock types.

Consider the below diagram of normal faulting. Diagram shows a downdropped block of rocks in between two upthrown blocks. Normal faults are to either side of the downthrown block. The diagram is labeled "Normal faulting". Which of the following statements is most likely true, based on the diagram?

It is the product of extensional forces.

How does deforestation by fire or human activity contribute to mass wasting?

It kills tree roots that help hold the slopes in place, allowing mass movement.

The Rocky Mountains of western North America were produced in an orogeny called the ________.

Laurenmide orogeny

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

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

Precambrian

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

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.

The picture below is a view of earth from the North Pole (above) and one from the South Pole (below). It shows ice sheets covering Greenland and Antarctica. Why are ice sheets primarily found in these regions? This is two map images of earth, the top image from the North Pole and the bottom image from the South Pole. The top image highlights Greenlands's ice sheet and the bottom image highlights Antarctica's ice sheets.

They are the coldest regions of the globe.

The 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.

Assume that water filling a crack in a rock undergoes cycles of freezing and melting. Which of the following statement is true?

Water expands as it freezes, causing the crack walls to be pushed apart.

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: sinkholes, soluble rock, caverns

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

What is the most abundant, naturally produced, weak acid involved in chemical weathering and soil formation?

carbonic

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

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

deposition of sediments shed from the eroding Rocky Mountains

Features like rock ledges in badlands or rock fins standing above adjacent valleys are all examples of ________.

differential weathering

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

Earth's primitive atmosphere evolved from gases ________.

expelled from within the earth

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

All of the following are factors affecting mass wasting except for ________.

geologic age

At the start of the Paleozoic, North America ________.

had no plants or animals

The below diagram is an example of what plate tectonic setting? Shows a subducting oceanic slab that is melting at depth and creating magma that rises to the surface to form volcanos that rise above the surface of the ocean. The oceanic lithosphere is subducting beneath more oceanic lithosphere. There is a trench right where the subduction is occurring. Asthenosphere is pictured below the oceanic lithosphere, beginning around 80 km down.

island-arc

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

Most stream valleys have a V shaped cross section because ________.

mass wasting of weathered rocks on the slope maintain an angle of repose slope

What kind of weathering involves only a reduction in the sizes of bedrock, regolith, and mineral particles?

mechanical

One important relationship between chemical and mechanical weathering is ________.

mechanical weathering can produce smaller pieces of rock that have more surface area for chemical weathering to work on

Orogenesis refers to the formation of ________.

mountains

Which of the following features characterize meandering streams and valleys?

natural levees; broad floodplains

Sediment deposition occurs primarily in what part of a river system?

near the outlet

Subduction occurs when ________ rocks are forced beneath ________ rocks.

oceanic; continental or oceanic

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

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

Which of the following is most resistant to both chemical and physical weathering?

quartz

A rancher overgrazes his land in an area underlain by heavy clay soils and regolith developed from weathering of claystone. After a series of heavy rains small creeks develop deep gullies along their length. A light steady rain develops and continues for several days. What should the rancher be concerned about on his overgrazed lands?

slumps along the creeks

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

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

the Mesozoic

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

the early rain was very acidic

Sediment production occurs primarily in ________ part of a river system.

the head waters

Which one of the following statements best describes erosion?

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

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

Mass wasting, a process that often occurs between weathering and erosion, involves ________.

the transport of material due to gravity

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

What two factors speed up rates of chemical reaction and weathering in rocks and soils?

warm temperatures; very moist

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

water is a major cause of erosion on land

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