Geological History and Climate Change Concepts

Major ice ages in Earth's history: 5 or 6 notable ice ages from the Cambrian period to present.
Duration of ice ages spans millions of years.
Certainty varies for some ice ages; while five are well-established, the existence of one remains debated.

The Snowball Earth Theory proposes that the polar regions were covered with ice.
Historical context and details about this theory were omitted due to time constraints.

Current geological period is the Quaternary, marking the last 2.6 million years.
The Quaternary period includes several ice ages characterized by fluctuating temperatures.

Definition of glacials (colder periods) separated by interglacials (warmer periods).
The Quaternary has experienced at least four significant continental ice advances.
Pleistocene: time of multiple glacials; Holocene: current warm period after the last glacial.

Wisconsin Glaciation: the last major glacial period with significant evidence of glacial structures still present today.
Most recent evidence of glacial erosion found in structures like striations made during this period.

North America was heavily covered by ice during the last glaciation, affecting geography and sea levels.
Sea levels dropped tens of meters due to the accumulation of ice on land, revealing land bridges for migration (e.g., Bering Land Bridge between Siberia and Alaska).

Great Lakes and other water bodies formed post-glaciation as ice retreated and landscapes adjusted.
Modern rivers such as the St. Lawrence River emerged as the ice melted.

Proglacial lakes formed due to meltwater collecting in depressions after ice retreat, leading to sediment deposition.
Isostatic rebound occurred as the ice melted, causing the land to gradually rise back up over thousands of years.

Moraines (accumulated glacial debris) provide information on the extent and retreat of glaciers.
Sediments in proglacial lakes allow researchers to trace ice retreat timelines and changes in the environment.

Climate has always fluctuated; changes can be due to several complex factors, notably orbital parameters affecting solar insolation:
- Eccentricity: the shape of Earth's orbit changes from circular to elliptical over periods of 100,000 years.
- Obliquity: the tilt of Earth's axis varies every 41,000 years, affecting seasonal temperatures.
- Precession: the wobble of Earth's axis occurs approximately every 26,000 years, influencing the Earth's climate.

Ongoing debate about the role of greenhouse gases (like CO2) in current climate change.
Current anthropogenic influences on climate may delay natural cycles, which typically suggest the onset of a new glacial period.

Current interglacial period (Holocene) has lasted approximately 12,000 years; projections indicate potential returns to colder periods based on historical cycles.
Importance of ongoing study into climate drivers and complex climate models to understand future changes in Earth's climate.

Exam format: 40 multiple choice questions, short answers, and 10 marks for a critical thinking question.
Study guide includes all discussed topics; emphasis on equal distribution across course content related to glaciation and Earth's structure.