Glaciers and Ice Ages

The Science of Glaciers and Ice Ages

Glaciers are massive, slow-moving bodies of dense ice that powerfully shape Earth’s geology.

• Formation: Glaciers form when snow accumulates over centuries and the sheer weight compacts it into dense, interconnected ice (firn). 
• Movement: Their immense weight and gravity cause a slight melting at the base, creating a slick layer of water. This allows the giant ice mass to slide and creep slowly downhill.
• Ice Age: An Ice Age is a long period characterized by a global temperature drop, leading to the significant growth of continental ice sheets and mountain glaciers.

Glacial Power: Erosion and Evidence

Glaciers are the most powerful agents of erosion on Earth.

• Glacial Power (Erosion): Glaciers act like giant bulldozers. They pluck (pick up) and abrade (grind) underlying rock, scraping the landscape as they flow.
• Landform Carving: This immense scraping action carves distinctive, deep U-shaped valleys and Fjords (U-shaped valleys flooded by the ocean).
• Geological Evidence: When glaciers melt, they leave behind evidence of their past existence, such as glacial till (unsorted sediment) and Erratic Boulders (rocks dropped far from their origin).

Fun Facts

Here are some interesting facts about glaciers and ice ages:

• During the last Ice Age, ice sheets were often 2 to 3 kilometers thick—taller than any building on Earth!
• If all the world’s glaciers and ice sheets melted, sea levels would rise by about 230 feet.
• Scientists can compare past CO2 levels with current levels by studying the air bubbles in ice cores to understand global warming.
• The blue color in glacier ice comes from dense ice absorbing red light and scattering blue light.

Review

Let’s quickly recap what we learned about glaciers and ice ages:

• What is the dense, compacted ice that makes up a glacier called? Firn
• What is the process by which a glacier scrapes and grinds bedrock? Abrasion
• What is the shape of a valley that a glacier has carved out? U-Shaped
• What records of ancient atmosphere are trapped inside glacial ice? Air Bubbles