Glaciers Lecture

Recent questions

• What causes glaciers to melt?

  Glaciers melt primarily due to climate change, which leads to an increase in global temperatures. As temperatures rise, the balance between snowfall and melting shifts, resulting in more melting than accumulation. This phenomenon is particularly pronounced at the poles, where warmer air pushes down colder air, exacerbating the melting process. Additionally, factors such as changes in precipitation patterns and warmer ocean currents can further contribute to glacier retreat. The visual markers left behind by glaciers, such as moraines and historical positions, indicate significant shrinkage over time, highlighting the urgent need to address climate change to preserve these vital ice formations.

• How do glaciers shape the landscape?

  Glaciers significantly reshape landscapes through processes of erosion and deposition. As glaciers move, they carve out U-shaped valleys, which are distinct from the V-shaped valleys formed by rivers. The immense weight and movement of glaciers can create features such as horns, cirques, and hanging valleys, which are often filled with waterfalls. Additionally, as glaciers advance and retreat, they leave behind various landforms, including moraines, eskers, and drumlins, which are formed from the sediment they carry. The Great Lakes, for example, were shaped by multiple glaciation events, demonstrating the profound impact glaciers have on the Earth's topography.

• What are glacial erratics?

  Glacial erratics are large boulders that have been transported and deposited by glaciers, often found in areas where the surrounding rock is different from the rock type of the erratic itself. These rocks provide evidence of past glacial movement, as they can be carried over long distances from their original locations. The study of glacial erratics was notably advanced by Louis Agassiz, who linked their presence to the movement of glaciers during the last ice age, which peaked around 24,000 years ago. Their presence in fields and other landscapes serves as a reminder of the dynamic processes of glaciation and the significant geological changes that have occurred over millennia.

• What are fjords and how are they formed?

  Fjords are deep, U-shaped valleys that have been flooded by seawater, typically formed by the retreat of glaciers. As glaciers advance and carve out valleys, they create steep-sided inlets. When the glaciers melt, these valleys can fill with ocean water, resulting in the formation of fjords. Commonly found in regions like Norway, Alaska, and Maine, fjords are characterized by their dramatic landscapes and deep waters. The process of glacial retreat and subsequent flooding by seawater creates unique ecosystems and scenic vistas, making fjords significant both ecologically and aesthetically.

• What is isostatic rebound?

  Isostatic rebound is the process by which land rises after the melting of glaciers. When glaciers are present, their immense weight compresses the Earth's crust. As glaciers melt, this weight is removed, allowing the crust to slowly rise back to its original position. This phenomenon is particularly evident in regions that were once covered by thick ice sheets, such as Wisconsin and the Netherlands. The rebound can lead to changes in local geography, including the emergence of land that was previously submerged. Isostatic rebound is a crucial aspect of understanding the long-term effects of glaciation on the Earth's surface and its ongoing geological processes.