There are over 3,000 glaciers in the Southern Alps of New Zealand, but some are easier to study than others.
Snow and rock avalanche hazards or difficult accessibility to a glacier may endanger equipment or people’s lives. This is why glaciologists tend to look for glaciers more like Brewster Glacier (pictured above) rather than Cameron Glacier (pictured below).
A crevasse is a break in the glacier surface, caused when a glacier flows over a steep cliff. I picture an accordion that is all pressed together then spreads apart. I have seen Snickers bar analogies as well. Then I made up my own analogy:
Don’t try this at home: Imagine 7-10 kids all holding onto a rope while they are spaced a few feet apart. Now imagine they are at the top of a slide and the first one goes down, that force will pull the rope and the next kid gets a jolt and part of the rope slips through. The glacier is one solid mass and the pulling force between the part of the glacier that wants to go down the slide and the part that is still just standing at the top of the slide causes the ice to crack and a crevasse forms.
New Zealand straddles the tectonic boundary between the Pacific and Indo-Australian plates. Mountain uplift gave rise to the Southern Alps, but what goes up must come down. The mountains in the central Southern Alps (the highest part) are crumbling apart from freezing and thawing, from glacial erosion, and from earthquakes and rock avalanches. This means the glacier has plenty of material with which to build large moraines.