20 Questions
What is the term used to describe the Earth's orbit changing from being perfectly round to slightly elliptical and then back to round?
Eccentricity
How often do major glaciation events occur according to the text?
Every 100,000 years
What is the cycle of the angle of tilt of the Earth's axis changing?
41,000 years
What is the term used to describe the direction of tilt of the Earth's axis changing?
Precession
What is the result of the combination of the three cycles?
A big swing in temperature
What is the prediction of scientists who study ice ages?
Another ice age will occur from now to 10,000 years from now
What happened to sea levels during the last ice age?
They dropped
How much did sea level drop during the Wisconsinan glacial maximum?
442 feet
What is one positive effect of ice ages on the Earth's surface?
The creation of lakes
What is the industry that is important along the Great Lakes?
Shipping
What is the primary reason why the earth's orbit changes from being perfectly round to slightly elliptical and then back to round?
The earth's orbit changes due to eccentricity
How do the glacial and interglacial cycles over the past 450,000 years relate to the frequency of major glaciation events?
They show a pattern of glacial cycles with a frequency of about 100,000 years
What is the effect of the three cycles combining in a positive or negative way?
It could lead to a major glaciation or a major heating period
What is the estimated time frame for the introduction of the next ice age?
It will happen between now and 10,000 years from now
What happened to the sea levels during the last ice age?
They dropped
What is the significance of the Great Lakes?
They are important for shipping and connect the East Coast with the iron ore deposits of the Mesabi Iron Range
What is the impact of an ice age on the earth's population?
It will displace millions of people
What is the significance of the temperature data over the past 20 years?
It shows a slight decrease in temperature
What is the significance of the caves near Gibraltar?
They show evidence of man inhabiting them during the last ice age
What is the result of the earth's surface being depressed by ice sheets?
It results in the formation of lakes
Study Notes
Glaciation Definition and Types
- Glaciation refers to the buildup and movement of ice on the earth's surface and the resulting formations and scars left on the ground and in mountain ranges.
- There are two types of glaciation: ice sheets and mountain glaciers.
Ice Sheets
- Ice sheets are massive bodies of compacted snow that can cover continents.
- The nuclei of ice sheets are the North and South poles.
- During periods of glaciation, the earth is colder, and ice sheets extend farther from the poles.
- Ice sheets can reach far into the temperate zones during extreme cold conditions.
Mountain Glaciers
- Mountain glaciers are formed in high mountain terrains and areas closest to the poles.
- They are formed due to elevation and proximity to the poles, inducing extreme snowfall.
- Glaciers can be found further away from the poles than ice sheets.
Effects of Glaciation
- Glaciation leads to a buildup of snow in cold regions that turns to ice due to compaction.
- The colder the earth gets, the larger and more extensive the glaciation becomes.
- Glaciation has a significant impact on the earth's surface, creating formations such as drumlin fields, moraines, kettle lakes, eskers, karnes, and erratics.
Examples of Glaciation
- The Great Lakes of North America were scoured out and deepened by the Arctic ice sheet.
- Features such as horns, cirques, aretes, truncated spurs, and medial moraines are carved into mountains by glaciers.
- U-shaped valleys, hanging valleys, and truncated spurs are examples of glaciation features.
Causes of Glaciation
- The amount and intensity of the sun's radiation heating the earth is the most significant contributor to glaciation.
- The position of the continents and the flow of ocean currents also play a role in glaciation.
- The Milankovitch theory attempts to explain why ice ages occur, citing three Earth variables: eccentricity, obliquity, and precession.
Effects of Glaciation on the Earth
- When glaciation occurs, sea levels drop as seawater evaporates and turns to snow, trapping it on continents.
- The effects of an ice age on the earth would be devastating, displacing millions of people.
- However, the depression created by ice sheets can lead to the formation of lakes, such as the Great Lakes, which are important for shipping and industry.
Learn about the formation and movement of ice on the Earth's surface, including glaciers and ice sheets. Test your knowledge of these natural wonders and their impact on the environment.
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