45 Questions
Approximately how long ago was the last glacial maximum?
18,000 years ago
Why did the coastline of North America look different 18,000 years ago compared to now?
There was a huge trench
What is the continental shelf?
The flooded part of the continent
What is the significance of the continental shelf in relation to the supercontinent Pangea?
It is a better fit when Pangea is reconstructed
How did glaciers modify the landscape?
By creating terminal moraines
During which epoch did the last glacial maximum occur?
Pleistocene epoch
What is the age of the ice ages?
Pleistocene epoch
Approximately when did the Pleistocene epoch occur?
3 million years ago
What percentage of Earth's land area was covered in ice during the Pleistocene epoch?
30%
Which hemisphere had more ice coverage during the Pleistocene epoch?
Northern hemisphere
What is the reason for the extensive ice coverage in the northern hemisphere during the Pleistocene epoch?
Presence of more land in the northern hemisphere
How does sea ice form?
Seawater freezes, leaving behind salt
Why was Alaska partially unglaciated during the Pleistocene epoch?
Alaska had warm water currents
What is the average global temperature decrease during ice ages?
3 to 5 degrees Celsius
What are positive feedback effects during ice ages?
Increased reflectivity of ice
Which mathematical model proposed the idea of ice ages based on variations in the Earth's orbit?
Milenkovic
What is the principal control of climate?
Latitude
What causes the change in seasons?
Tilt of the Earth's axis
Which of the following is NOT one of the orbital effects that contribute to ice ages?
Axial tilt
What is the approximate duration of the cycle for eccentricity?
100,000 years
Which latitude is thought to be critical for the formation of ice sheets during ice ages?
5 degrees
Which region in California experiences some of the highest average annual precipitation?
Coast Range
What is the principal agent of erosion in deserts?
Water
How is a desert defined?
By the amount of precipitation it receives
During which time frame do we go through one cycle of the Milankovitch cycles?
100,000 years
What is the modern definition of a desert?
Any area with more water leaving than coming in
What percentage of Earth's land surfaces are deserts?
30%
What is the main cause of the distribution of deserts on Earth?
Global wind pattern
What is the effect of the Himalayas on the global wind pattern?
It changes the global wind pattern
Why is the Great Basin desert located at a higher latitude than expected?
The effect of mountain ranges
Which of the following features is an erosional feature in the basin and range region?
Insulbergs
What causes wind erosion in deserts?
Deflation
What is the term for a large hole in the desert caused by wind blowing away loose material?
Blowout
Which direction does the wind blow in the Sahara Desert?
South
What is the term for the sand that is carried by a stream in the bed load?
Saltation
What is the principal agent of erosion in deserts?
Wind
What is the term for the process of sand grains being blasted against rocks by the wind?
Abrasion
Which term describes the hard covering of sand in a desert environment that prevents deflation?
Desert pavement
What was the main cause of the dust bowl in the United States in the late 1920s and early 1930s?
Over farming
Which depositional feature is associated with sand dunes?
Cross beds
What do cross beds indicate in a sand dune environment?
Direction of sand movement
What is the purpose of determining wind direction and sand concentration in sand dunes?
To understand the formation of sand dunes
What is the term for wind-blown silts that caused the dust bowl in the United States?
Loess
What is the term for the areas where sand is sliding down in a sand dune?
Slip faces
What is the term for the patterns formed by sand dunes?
Sand dune patterns
Study Notes
Understanding Ice Ages and Climate Change
- The Pleistocene epoch occurred approximately 3 million years ago.
- The Pleistocene epoch is part of geologic time, specifically the division after which we are currently in, the Holocene.
- During the Pleistocene epoch, 30% of Earth's land area was covered in ice, with the northern hemisphere having twice as much ice as the southern hemisphere.
- The extensive ice coverage in the northern hemisphere is due to the presence of more land in that region, which is necessary for the formation of continental ice sheets.
- Sea ice forms when seawater freezes, leaving behind the salt, resulting in relatively fresh water on the surface.
- Alaska was partially unglaciated during the Pleistocene epoch due to the circulation of warm water currents that moderated the climate in that region.
- Ice ages occur due to a cycle of global cooling, which can bring average global temperatures down by 3 to 5 degrees Celsius.
- Ice ages are characterized by positive feedback effects, where the presence of ice leads to further cooling and expansion of ice coverage.
- Positive feedback effects during ice ages include increased reflectivity of ice, which reflects more sunlight and lowers temperatures further, and the depression of continents, which also contributes to cooling.
- The presence of ice sheets during ice ages significantly alters the Earth's albedo, or reflectivity, which affects the amount of solar radiation absorbed or reflected back into space.
- Ice ages are part of large-scale climatic cycles that have occurred throughout Earth's history, with periods of both colder and warmer climates.
- Plate tectonics, such as the separation of continents like South America and Antarctica, can influence ocean currents and contribute to climate patterns, further affecting ice ages.
Test your knowledge of ice ages and climate change with this quiz! Learn about the Pleistocene epoch, the formation of ice sheets, the feedback effects of ice ages, and the role of plate tectonics in influencing climate patterns. Discover how these large-scale climatic cycles have shaped Earth's history.
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