Episode 129: Glaciers, Ice, and Groundwater

Moraines

Moraines are significant glacial formations that provide insights into the movement and history of glaciers. James Fodor explains that moraines can form along the edges, middle, or end of a glacier, known as lateral, medial, and terminal moraines, respectively. These formations consist of rock and sediment deposited by the glacier, and their locations can indicate past glacier extents 1. Additionally, ground moraines spread over large areas, offering clues about the glacier's path and behavior 2.

Moraines are important because they kind of tell you about the shape and structure and trajectory, if you like, of the glacier.

--- James Fodor

Understanding moraines helps reconstruct historical glacial movements and predict future changes in glacial landscapes.

   

Drumlins and Eskers

Drumlins and eskers are unique glacial landforms that reveal the dynamics of past glacial activity. Drumlins are asymmetrical, canoe-shaped hills formed by the movement of continental glaciers over underlying rock or sediment, often found at the base of valleys 3. Eskers, on the other hand, are long, winding ridges of stratified sand and gravel, formed from sediment deposits in ice-walled tunnels of streams that flowed within or beneath glaciers 4.

Eskers are formed mostly from ice-walled tunnels of streams that used to flow either within or underneath the glacier.

--- James Fodor

These landforms provide valuable information about the sediment transport and depositional processes of glaciers.

   

Cirques and Arêtes

Cirques and arêtes are prominent erosional features in glacial landscapes. Cirques are bowl-shaped depressions found at the head of glacial valleys, marking the origin of glaciers and characterized by their steep sides and flat bottoms 5. Arêtes are narrow ridges of rock that separate parallel u-shaped valleys formed by glacial erosion 6.

An arête is a narrow ridge of rock that separates two valleys.

--- James Fodor

These features highlight the powerful erosive capabilities of glaciers and their role in shaping mountainous terrains.

   

Fjords

Fjords are dramatic coastal landforms created by the action of glaciers. They are u-shaped valleys carved by glaciers that have been filled with ocean water, forming deep, narrow inlets 5. James Fodor notes that fjords are particularly common in regions like Norway, which were heavily glaciated during the last glacial maximum.

Fjords are basically the leftover, scraped out, gouged out, u-shaped valley from a past glacier.

--- James Fodor

These stunning landscapes serve as a testament to the immense power of glacial erosion and the lasting impact of glaciers on the Earth's surface.