Chapter 36 - Glacial Erosion

Erosion be means of a glacier can often take place through plucking (quarrying). The glacier pulls blocks or fragments of bedrock from the bed up into the bottom of the glacier as it moves forward. These blocks or fragments of bedrock scrap across the bedrock in the bed below, a process known as abrasion. Ice in itself is not a very hard substance, on the Mohs scale it is a 1.5; ice is only an effective agent of erosion through the abrasion. When the rock fragments that the glacier carries are very hard the abrasion process will leave striations in the bedrock below. These striations are scratches are often metres in length and centimetres (often millimetres) deep. This video shows striations left behind from glacial abrasion at the Columbia ice-field.