Ch 14 Geo 105

9. How does a fiord form?

A fiord was a glacier filled valley when sea level was much lower. When glaciers melted and sea level rose the valley was flooded.

10. Briefly explain how a hanging valley forms.

A hanging valley forms from the eroded valley of a tributary valley glacier which met the trunk valley glacier at an elevation high above the valley floor of the latter.

A glacier begins to flow when the ice reaches what critical thickness? a. 100 meters b. 40 meters c. 20 meters d. 10 meters e. 5 meters

B

In a cross-section of a glacier, where do the greatest flow velocities occur? a. at the surface b. in the few tens of meters below the surface c. in the few tens of meters above the base d. at the base e. in the center of the flow

B

Straight scratches on rock surfaces created by glacial abrasion are known as what? a. rock flour b. glacial striations c. glacial till d. varves e. moraines

B

When did the Pleistocene Ice Age end? a. 1.8 million years ago b. 10,000 years ago c. 1,300 years ago d. 200 years ago e. It still hasn't ended.

B

If glacial ice were a rock it would be a(n) _______ rock. a. igneous b. sedimentary c. metamorphic d. glacial ice cannot be a rock

C

In the process of sublimation a. ice melts to become liquid water, which then evaporates. b. fresh snow becomes firn and then glacial ice. c. ice changes directly into water vapor. d. white ice becomes denser so that blue wavelengths are transmitted and scattered and the ice appears blue.

C

What is a lake formed within a cirque called? a. arête b. esker c. tarn d. fjord e. drumlin

C

6. Why do continental glaciers generally flow more slowly than valley glaciers?

Continental glaciers are relatively slow because there is little basal meltwater in the high latitudes where they occur, and thus, basal slip is limited.

A glacier that is unconfined by topography and has tributaries is a a. ice cap. b. tributary glacier. c. continental glacier. d. valley glacier.

D

Glacial till is ____. a. any sediment deposited as a result of glacial activity b. boulders transported long distances and deposited by glaciers c. an elongated spoon-shaped hill that has been shaped by an overriding glacier d. unstratified sediment deposited directly by a glacier e. a lake within an outwash plain.

D

Ice Ages a. have been common through Earth history. b. have glacial episodes separated by very short interglacial stages. c. are caused primarily by plate tectonics. d. are the result of variations in the amount of solar heat received.

D

13. What are dropstones, and what do they indicate?

Dropstones are gravel- to boulder-sized rocks found in otherwise fine-grained glacial lake deposits. They indicate transport of the rocks into the lake by icebergs that eventually melted, releasing the coarser sediment.

14. Briefly explain the origin of drumlins.

Drumlins form beneath moving ice that molded glacial drift into a characteristic streamlined shape.

A glacial landform that forms at the head of glacial valleys or troughs is called a(n) ____. a. roche moutonnée b. esker c. kame d. arête e. cirque

E

Where is the largest existing glacier located? a. Greenland b. Alaska c. The Alps d. Patagonia e. Antarctica

E

Which is the only continent that does not presently have glaciers? a. South America b. North America c. Africa d. Europe e. Australia

E

12. What are eskers and how do they form?

Eskers are long, sinuous ridges of stratified drift. They form in tunnels beneath stagnant ice and in meltwater channels on the surface of glaciers.

T/F A conical hill of stratified drift is an esker

F

T/F A strong correlation has been established between periods of intense volcanism and short-term glacial cooling

F

T/F There is good evidence that variation in solar energy, as evinced by sunspot activity cycles, is responsible for short-term climatic variations

F

T/F Valleys carved by glaciers are distinctive because they are V-shaped in cross-section

F

2. Under what conditions can glaciers exist in the equatorial latitudes?

Glaciers can occur even at equatorial latitudes, at high enough elevations.

The climatic event that began with cooling in about AD 1300 and lasted until the middle 1800s is known as the Little ____________________.

Ice Age

8. What are some of the characteristics of large ice-scoured plains, such as those of the Canadian Shield region?

Ice-scoured plains have deranged drainage, little or no soil, extensive bedrock exposures, low relief, and numerous lakes and swamps.

11. Explain how medial moraines develop.

Medial moraines develop by the coalescence of two lateral moraines when two glaciers merge.

The present glacial landscapes mainly formed during the ____________________ Epoch, which lasted from ____________________ years to ____________________ years ago.

Pleistocene, 1.8 million, 10,000

T/F A steep-walled, pyramidal peak formed by headward erosion of cirques

T

T/F Basal slip becomes a more important means of glacier movement in warmer months when more meltwater collects at a glacier's base

T

T/F Earth's orbit varies from nearly circular to more elliptical in a roughly 100,000-year cycle

T

T/F End moraines continue to grow as long as the ice front remains stationary

T

T/F Glaciers are geologically important because they erode, transport, and deposit so much material

T

T/F The Little Ice Age ended in the mid to late 1800s

T

T/F The decade from 2000 to 2009 was the hottest on record so far.

T

5. How can the boundary between the zones of accumulation and wastage on a glacier be located during the spring and summer?

The boundary can be found by locating the firn limit; that is, the elevation to which snow recedes during a wastage season.

7. Name some erosional landforms that might help you recognize that a valley had previously been occupied by a valley glacier.

U-shaped valley trough, truncated spurs, fiords, hanging valleys, cirques, tarns, arêtes, horns

4. Is ice a mineral? Explain.

Yes, ice is a mineral. It is a naturally-occurring, inorganic substance with a distinct chemical composition and physical structure.

In general, rates of glacial flow are greatest in the zone of ____________________.

accumulation

The zone of ____________________ is the portion of a glacier where additions exceed losses.

accumulation

3. How does the water bound in glaciers eventually re-enter the hydrologic cycle?

by calving and melt water runoff

The two major types of glaciers are ____________________ and ____________________.

continental, valley

The presence of ____________________ in the upper 40 m or so of a glacier indicates that this portion behaves not as a plastic, but as a(n) ____________________ solid.

crevasses, brittle

Any sediment deposited as a result of glacial activity is known as glacial ____________________.

drift

The Matterhorn in Switzerland is a glacial ____________________ landform known as a(n) ____________________.

erosional, horn

When snow thaws and refreezes, which results in a loss of air and pore spaces, the result is ____________________.

firn

An ice mass of compacted and recrystallized snow that flows under its own weight on land is called a(n) ____________________.

glacier

The zone of wastage is the portion of a glacier where ____________________ exceed ____________________.

losses, accumulation

Glaciers move primarily by ____________________ flow.

plastic

15. What is a possible explanation for long-term variations in Earth's climate?

plate tectonic movement of continents

The fine, clay- and silt-sized particles that result from glacial pulverization of rock is known as ____________________.

rock flour

1. From the human perspective, what climatic effect of the Little Ice Age had the greatest impact?

shorter, cooler, and wetter summers

The three stages involved in the formation of a glacier are the precipitation of ____________________; the formation of ____________________ by partial thawing, refreezing, and crystallization; and compaction and recrystallization to produce ____________________.

snow, firn, glacial ice

A glacier that is now longer flowing is called a(n) ____________________ glacier.

stagnant

The distal end or edge of the glacier is called its ____________________.

terminus

Finely laminated, alternating light and dark layers of sediment deposited in a glacial lake are known as glacial ____________________.

varves

A glacial landform produced primarily by plucking rocks on the downstream side and smoothing by the glacier on the upstream side is called a(n) ____. a. roche moutonnée b. esker c. kame d. terminal moraine e. cirque

A

A glaciers budget is balanced when a. additions to the zone of accumulation equal losses in the zone of wastage. b. losses in the zone of accumulation equal additions to the zone of wastage. c. the zone of accumulation receives more input than the zone of wastage. d. the zone of wastage does not lose material.

A