Glaciation II

Cryosphere

Any part of the Earth where water is
frozen

Glaciers

• large, slow-moving mass of ice that forms from compacted snow over time

• found in areas of high latitude or high altitude

• Cover 10% of Earth’s surface

Greenhouse cycle

Period when Earth is warm, with no permanent ice sheets

More stable and more common

Icehouse cycle

Period when Earth is colder, with ice at the poles.

Shorter and fluctuant

Ice-Albedo Effect

• Formation of Earth ice sheets in icehouse regimes following snowball effect

• Ice forms on Earth’s surface, it reflects sunlight

• Absorbs less solar energy, Earth cools and ice grows

• More ice, more reflection, less absorption . . .

Snowball Earth

• Ice Albedo Effect

• Continents come together = lots of mountain building, little volcanism

• Ends when continents break apart, triggering volcanism, warming the planet and shifting toward a greenhouse period.

Glacials

• Cold and dry

• Ice extending to lower latitudes and altitudes

Interglacials

• Cool and damp

• glaciers shrink due to warmer temperatures. Ice melts, sea levels rise

Causes of Glaciation (Ice Growth) (M.I.P.V)

• Milankovitch Cycle - Changes in Earth’s orbit and tilt reduce sunlight, cooling planet

• Ice Albedo-Effect - More ice reflects sunlight, reinforcing cooling

• Plate tectonics - Continents shifting to high latitudes allow ice sheets to form

• Reduced Volcanism - Less CO2, from volcanoes means less warming

Ends of Glaciation (Ice Melting) (M.I.P.V)

• Milankovitch Cycles – More sunlight warms the planet.

• Increased CO₂ – Volcanic activity or ocean release of CO₂ traps heat.

• Melting ice - exposes land/water, absorbing heat.

• Tectonic Changes – Continents move, altering ocean currents and warming climate.

Milankovitch Cycles (Egg, Obliques, Poles)

• Eccentricity - Earth’s orbit changes from circular to oval, affecting how much sunlight we get.

• Obliquity - Earth’s tilt changes, affecting seasons.

• Precession - pole pointing toward different direction (“wobbling”)

Laurentide Ice Sheet

massive glacier that covered Canada and parts of the northern U.S. during the last Ice Age. It shaped landscapes, created the Great Lakes, and melted about 10,000 years ago, raising sea levels.

Pluvial Lakes

• During the Ice Age, more glaciers meant more moisture in the air

• increased rainfall.

• rain filled low areas, creating large lakes in dry regions like the western U.S.

• After the Ice Age, rainfall decreased, and the lakes dried up.

Glacial Melting

Retreat of glaciers during an interglacial, releasing water that raises sea levels and reshapes landscapes

Isostacy

• Earth's land rises or sinks due to the weight of ice.

• When glaciers melt, the land that was pressed down rises back up.

• can change rivers, coastlines, and create raised beaches.

Discuss the effects recent glaciation has had on North America

• rising of land after glaciers melted (isostatic rebound),

• the formation of lakes, altered rivers

• The weight of the glaciers also caused some areas, like the Outer Banks, to sink.

Human-Induced Climate Change

adding CO2 to the atmosphere, which raises temperatures. This warming causes glaciers to melt faster, delaying the natural process of glaciation and making it recede at an unusually fast rate.

How glaciers form and move

Forms:

1. Snow falls and builds up over time in cold regions.

2. The layers of snow compress

3. Snow turns into dense ice (glacial ice).

   Moves:

4. Gravity – pulling the ice mass downward.

5. Internal flow – ice inside the glacier bends and flows

6. Basal sliding – the bottom of the glacier may slide over meltwater, helping it move.

Glacial Budget

the balance between how much ice a glacier gains (accumulation) and how much it loses (ablation).

Glacial Erosion

Glaciers erode land by plucking and scraping, shaping it into U-shaped valleys and other features.