Glaciers and Landscape: Background information when reading Grist Mill Road

Glaciers and Landscape

This article relates to Grist Mill Road

In Grist Mill Road, readers are treated to a mini lesson in how glaciers can shape landscape. Chatter marks, cobbles, and glacial erratics are all terms we come across in the story. What are they and how does a glacier alter the landscape over the ages?

When a large and heavy object moves very very slowly it has the potential to greatly impact its surroundings. Glaciers alter the landscape in two fundamental ways: they carve out valleys (think fjords) and transport significant volumes of debris including rocks.

Glaciated valleys are created when glaciers pass through large mountains. If you notice sheer mountain cliffsides with very narrow inlets, those are likely carved by glaciers. Fjords in Norway are trough-shaped with steep sides. As the inlets or valleys are carved, other bodies of water fill in the space. A cirque is a rounded shape on a mountainside, almost like an amphitheater, which is carved by glaciers too.

Have you ever hiked the woods and run into a huge boulder right in the middle of a path? You probably spotted a glacier erratic, large rocks that got transported and left behind by a glacier eons ago. A glacier erratic is moved from its original location and stays in place as the water melts underneath it. Sometimes rock faces will have what look like scratch marks all along the surface. These are known as glacial striations or chatter marks and are formed from sharp glacier edges making their way slowly along the rock wall.

Walking around the Swangum Mountains in Grist Mill Road, Matthew learns about the glacial formations that form a formidable part of the landscape.

Glacial Erratics, courtesy of nsidc.org
Fjords, courtesy of www.visitnorway.com
Chatter marks, courtesy of www.landforms.eu

Filed under Nature and the Environment

This "beyond the book article" relates to Grist Mill Road. It originally ran in January 2018 and has been updated for the December 2018 paperback edition. Go to magazine.