Climate And Ice Ages Flashcards
What are ice sheets?
Ice sheets are large masses of glacial ice that cover extensive areas of land.
How widespread were ice sheets 25,000 years ago?
During this time, the Earth was much colder, and significant parts of the world, especially in the northern hemisphere, were covered by ice sheets.
What does the map of ice sheets show?
It highlights regions of the world that were under ice sheets 25,000 years ago, including:
- North America
- Northern Europe
- Northern Asia
Why was the Earth colder 25,000 years ago?
This period was part of the last Ice Age, where global temperatures were much lower than today.
What is a glacial period?
A very cold period when much of the Earth is frozen. Ice spreads further from the poles toward the equator.
What is an interglacial period?
A warmer period between glacial periods. Permanent ice is restricted to the North and South Poles.
What period is the Earth currently in?
The Earth is currently in an interglacial period.
How has Earth’s climate changed over the last 450,000 years?
The Earth’s climate has cycled between glacial and interglacial periods.
What are ice ages?
Long periods of extreme cold, including cycles of glacial and interglacial periods.
Scientists think the second major ice age, around 850 million years ago, was the coldest, and the Earth might have resembled a giant snowball.
How do scientists study ice ages?
By analyzing temperature changes over millions of years, shown in graphs with patterns of cooling (glacial periods) and warming (interglacial periods).
How many ice ages have there been on Earth?
Scientists think there have been five major ice ages in Earth’s history.
Is the Earth in an ice age now?
Yes, the Earth is in an ice age because there is still permanent ice at the poles.
We are currently in an interglacial period within this ice age.
What is the difference between a glacial period and an ice age?
Ice Age: A long-term period of cold climate with cycles of glacial and interglacial periods.
Glacial Period: A colder phase within an ice age where ice spreads further from the poles.
How do scientists know the Earth was colder in the past?
By observing boulders (large rocks) left behind by glaciers.
Glaciers, which are rivers of ice, carry rocks as they move. When glaciers melt, these rocks are deposited.
Evidence:
Scratches on rock surfaces caused by moving glaciers.
Fossils of animals and plants adapted to cold climates found in areas that are warm today.
How do glaciers affect the landscape?
Glaciers erode rocks, forming deep valleys like the Grand Canyon.
They leave behind marks and rocks, reshaping the landscape as they move and melt.
How can scientists use pollen to study past climates?
Scientists analyze pollen from peat bogs to identify plants that lived in the past. Different plants indicate specific climates because each type thrives in certain conditions.
What is a peat bog?
A peat bog is an accumulation of partially decayed plant material in wet, oxygen-poor, and slightly acidic conditions. Decay is very slow in peat bogs, preserving layers of organic material.
How do peat bog layers help scientists?
The layers represent different periods of history. Deeper layers are older, allowing scientists to study changes over time.
What tool is used to extract samples from a peat bog?
An auger is used to remove a core sample from the peat bog.
What did scientists discover from the deepest soil layer in the core?
The deepest soil layer in the core was formed 237,000 years ago. By identifying the plants from the pollen, scientists reconstructed the climate from that time to the present.
Why is pollen analysis important?
Pollen reveals the types of plants that grew in different periods, which helps scientists determine past climates during glacial and interglacial periods.
