What is meant by glacial mass balance? What are the basic inputs and outputs contributing to that balance? What is meant by a glacier surge? What do scientists think produces surging episodes?...

What is meant by glacial mass balance? What are the basic inputs and outputs contributing to that balance? What is meant by a glacier surge? What do scientists think produces surging episodes?

Describe the transformation of a V-shaped stream valley into a U-shaped glaciated valley. What features are visible after the glacier retreats?