Study Guide for Lecture Exam #3 (cont’d.)
STUDY GUIDE FOR LECTURE EXAM #3
EXAM IS NOT A CUMULATIVE FINAL
EXAM WILL COVER CH. 9, 10, 12, 13, 14, & 15
Peter N. Nassar, Ph.D. George Washington University 1 November
2023
Email: GEOL 1005 Environmental Geology
You will receive two hours (120 minutes) to take Lecture Exam #3, as opposed to the usual 60
minutes, due to the exam occurring during finals week. Lecture exam #3, however, will be about
the same length (and about the same number of questions) as lecture exams #1 and #2. DSS
students will receive their usual accommodations (i.e., 1.5x [180 minutes] or 2x [240 minutes]).
Lecture Exam #3 is not a cumulative final exam.
The exam is closed-notes, closed book. No study aids. There will be approximately 50
questions, and the format will be multiple-choice, true-false, and possibly some short-answer
questions.
The study guide below is meant to serve as an overview for what to study. As before, the
majority of the exam questions will come from the topics listed below, but I reserve the right to
ask questions on topics not directly related to or mentioned on the study guide (i.e., I may ask
questions directly from the required textbook readings). You should be familiar with the entirety
of the chapters listed below unless told otherwise. Please also note the study guide is meant to be
comprehensive, i.e., not everything listed on the study guide will be featured on the exam.
Your lecture handouts, along with your textbook, contain much of the information found below.
The page numbers listed after each question refer to where the information can be found in your
textbook.
Ch. 9: Ice, Glaciers, Wind, Deserts (pp. 213 – 235)
1. What is a glacier? What conditions are needed for one to form? (p. 214-215)
Glaciers: masses of ice that move under their own weight, under the force of gravity.
For glaciers to form, the following conditions must be met (in addition to cold temperatures):
a. Precipitation: glaciers are, after all, reservoirs of frozen water.
b. A higher rate of snowfall than melt each year. This allows the glacier to grow over
time.
c. Mountains (i.e., higher elevations → colder temperatures): most glaciers begin in the
mountains as snow
d. patches that survive the summer. This is favored on north-facing slopes, which
receive less direct sunlight.
e. Gentle slope: if the slope is > 30°, avalanches may form, clearing the glacier away
2. What is the relationship between snow, firn, and ice? (p. 215)
Snow changes to firn, a texture that is in between that of ice and snow. It recrystallizes into
2
, Study Guide for Lecture Exam #3 (cont’d.)
denser glacial ice as a result of the surrounding ice packing the firn tighter and thicker over
time.
3. What is the difference between an alpine and continental glacier? Which are more numerous
today? Where are continental glaciers found today? (p. 215)
Alpine glaciers are smaller glaciers that originate at high altitudes and occupy valleys in hilly
terrain as a result of low temperatures. Larger glaciers that extent huge tracts of land and are
found close to the poles are called continental glaciers, sometimes referred to as ice caps or ice
sheets. These days, alpine glaciers are more widespread. Greenland and Antarctica both have
continental glaciers.
4. What is the difference between the rigid zone and the plastic zone of a glacier? At what
depth is the boundarybetween the two zones? (see lecture notes, pp. 1-2; textbook Fig. 9.5, p.
216)
A glacier's rigid zone is where crevasses form and the highest point of most fast movement
occurs. The intermediate area of the glacier where the ice layers slide over one another is
known as the "plastic zone." Normally, the depth of the border between the two zones is
about 50 meters.
5. How does a glacier form? What is the difference between the zone of ablation and the zone
of accumulation? (pp. 216-217)
Glaciers are formed when snow builds up and turns into ice. In the zone of accumulation,
snow builds up and the glacier expands; in the zone of ablation, ice melts or evaporates and
the glacier retreats.
6. By what process do glaciers move / slide? (p. 216)
There are three processes of glacial movement that glaciers move through: base sliding, plastic
zone, and rigid zone. When a glacier melts at its base, a layer of water is created that causes the
glacier to slide as a whole. This process is known as basal sliding.
7. What is the difference between how a U-shaped vs a V-shaped valley formed? (p. 217)
The erosion of a glacier, which scoops out the valley and forms steep sides, results in a valley
with a U shape. The narrower, V-shaped profile of a valley generated by stream or river erosion
is called a V-shaped valley.
8. Be able to define the following terms: cirque, arête, horn, glacial striations, glacial
till, lateral moraine, middle (or medial) moraine, terminal moraine (pp. 218-219)
Cirque: a depression at the head of a glacial valley that resembles a bowl.
Arête: a slender, acute ridge dividing two glacier valleys or cirques.
Horn: a sharp peak created by the glaciers' multiple-sided erosion.
Glacial striations: parallel ridges carved into a rock's surface by glacier action.
Glacial till: sediment left behind by a glacier that is made up of a variety of particle sizes.
Lateral moraine: a till ridge that runs alongside a glacier.
Middle (or medial) moraine: When two glaciers combine and their lateral moraines
unite, a till ridge is created.
Terminal moraine: a till ridge designating a glacier's furthest progress.
9. Where are some geographic areas within North America whose landscapes have been
influenced by glacial activity? (p. 219)
3
STUDY GUIDE FOR LECTURE EXAM #3
EXAM IS NOT A CUMULATIVE FINAL
EXAM WILL COVER CH. 9, 10, 12, 13, 14, & 15
Peter N. Nassar, Ph.D. George Washington University 1 November
2023
Email: GEOL 1005 Environmental Geology
You will receive two hours (120 minutes) to take Lecture Exam #3, as opposed to the usual 60
minutes, due to the exam occurring during finals week. Lecture exam #3, however, will be about
the same length (and about the same number of questions) as lecture exams #1 and #2. DSS
students will receive their usual accommodations (i.e., 1.5x [180 minutes] or 2x [240 minutes]).
Lecture Exam #3 is not a cumulative final exam.
The exam is closed-notes, closed book. No study aids. There will be approximately 50
questions, and the format will be multiple-choice, true-false, and possibly some short-answer
questions.
The study guide below is meant to serve as an overview for what to study. As before, the
majority of the exam questions will come from the topics listed below, but I reserve the right to
ask questions on topics not directly related to or mentioned on the study guide (i.e., I may ask
questions directly from the required textbook readings). You should be familiar with the entirety
of the chapters listed below unless told otherwise. Please also note the study guide is meant to be
comprehensive, i.e., not everything listed on the study guide will be featured on the exam.
Your lecture handouts, along with your textbook, contain much of the information found below.
The page numbers listed after each question refer to where the information can be found in your
textbook.
Ch. 9: Ice, Glaciers, Wind, Deserts (pp. 213 – 235)
1. What is a glacier? What conditions are needed for one to form? (p. 214-215)
Glaciers: masses of ice that move under their own weight, under the force of gravity.
For glaciers to form, the following conditions must be met (in addition to cold temperatures):
a. Precipitation: glaciers are, after all, reservoirs of frozen water.
b. A higher rate of snowfall than melt each year. This allows the glacier to grow over
time.
c. Mountains (i.e., higher elevations → colder temperatures): most glaciers begin in the
mountains as snow
d. patches that survive the summer. This is favored on north-facing slopes, which
receive less direct sunlight.
e. Gentle slope: if the slope is > 30°, avalanches may form, clearing the glacier away
2. What is the relationship between snow, firn, and ice? (p. 215)
Snow changes to firn, a texture that is in between that of ice and snow. It recrystallizes into
2
, Study Guide for Lecture Exam #3 (cont’d.)
denser glacial ice as a result of the surrounding ice packing the firn tighter and thicker over
time.
3. What is the difference between an alpine and continental glacier? Which are more numerous
today? Where are continental glaciers found today? (p. 215)
Alpine glaciers are smaller glaciers that originate at high altitudes and occupy valleys in hilly
terrain as a result of low temperatures. Larger glaciers that extent huge tracts of land and are
found close to the poles are called continental glaciers, sometimes referred to as ice caps or ice
sheets. These days, alpine glaciers are more widespread. Greenland and Antarctica both have
continental glaciers.
4. What is the difference between the rigid zone and the plastic zone of a glacier? At what
depth is the boundarybetween the two zones? (see lecture notes, pp. 1-2; textbook Fig. 9.5, p.
216)
A glacier's rigid zone is where crevasses form and the highest point of most fast movement
occurs. The intermediate area of the glacier where the ice layers slide over one another is
known as the "plastic zone." Normally, the depth of the border between the two zones is
about 50 meters.
5. How does a glacier form? What is the difference between the zone of ablation and the zone
of accumulation? (pp. 216-217)
Glaciers are formed when snow builds up and turns into ice. In the zone of accumulation,
snow builds up and the glacier expands; in the zone of ablation, ice melts or evaporates and
the glacier retreats.
6. By what process do glaciers move / slide? (p. 216)
There are three processes of glacial movement that glaciers move through: base sliding, plastic
zone, and rigid zone. When a glacier melts at its base, a layer of water is created that causes the
glacier to slide as a whole. This process is known as basal sliding.
7. What is the difference between how a U-shaped vs a V-shaped valley formed? (p. 217)
The erosion of a glacier, which scoops out the valley and forms steep sides, results in a valley
with a U shape. The narrower, V-shaped profile of a valley generated by stream or river erosion
is called a V-shaped valley.
8. Be able to define the following terms: cirque, arête, horn, glacial striations, glacial
till, lateral moraine, middle (or medial) moraine, terminal moraine (pp. 218-219)
Cirque: a depression at the head of a glacial valley that resembles a bowl.
Arête: a slender, acute ridge dividing two glacier valleys or cirques.
Horn: a sharp peak created by the glaciers' multiple-sided erosion.
Glacial striations: parallel ridges carved into a rock's surface by glacier action.
Glacial till: sediment left behind by a glacier that is made up of a variety of particle sizes.
Lateral moraine: a till ridge that runs alongside a glacier.
Middle (or medial) moraine: When two glaciers combine and their lateral moraines
unite, a till ridge is created.
Terminal moraine: a till ridge designating a glacier's furthest progress.
9. Where are some geographic areas within North America whose landscapes have been
influenced by glacial activity? (p. 219)
3
