The world today would look very different were it not for glaciers, the icy bulldozers that—over many thousands of years—carved out landforms such as fjords and America's Great Lakes. As it turns out, those impressive claims to fame are just the tip of the iceberg. Here are a few more fascinating facts about the massive bodies of ice and snow.

1. There's a size requirement.

Proper glaciers must be a minimum of .1 square kilometers—that's almost 25 acres, or nearly 19 football fields!

2. The Largest Glacier on Earth is 60 Miles Wide and Around 270 Miles Long.

That would be Antarctica’s Lambert glacier, named after former Australian director of national mapping Bruce P. Lambert, who helped chart out the area during the late 1950s.

3. They Behave Like Really, Really, REALLY Slow-Moving Rivers.

Like the mighty Mississippi, glacial ice—which is driven by gravity—flows from high to low elevations. In the process, it often removes and transports chunks of rock (called “glacial erratics”), sometimes across a few hundred miles.

4. They’re Formed by Snowflakes and Time.

The most vital ingredient for glacier-making is a location where snow stays put year-round. When new layers arrive each winter, they start to crush existing blankets. All that weight distorts the snow crystals that make up the older layers, turning them into sugar-like grains. As time passes, these grains get bigger and denser until, eventually, genuine glacial ice is produced.

5. Glaciers Contain an Estimated 69 Percent of the World’s Fresh Water Supply.

By comparison, lakes, rivers, swamps, and similar bodies can only claim a combined 0.3 percent.

6. There are around 100,000 in Alaska.

These cover some 28,000 square miles of the 49th state. Provided they have the right permit, Alaskans are legally allowed to harvest glacial ice.

7. If Every Glacier and Ice Sheet on Earth Suddenly Melted, Global Sea Levels Would Rise by Over 260 Feet.

Hasta la vista, LA and London! Also, parts of southern Missouri might become great locations for beachside condos.

8. Glaciers Can Move At a Rate of Over 50 Feet Per Day.

In the summer of 2012, the Jakobshavn Glacier in Greenland set a new world record by traveling an impressive—by glacial standards, at least—150 feet per day.   

9. There Are Two Main Types.

Alpine glaciers flow downwards from mountaintops and slide through valleys. Continental glaciers, on the other hand, are large, horizontal expanses that aren’t seriously affected by the hills or mountains they cover. They generally dwarf their alpine counterparts.

10. During the peak of the Last Ice Age, Glaciers Covered About a Third of Earth's Land.

Over the past two billion years, our little blue planet has withstood at least five main ice ages. The latest one has spanned from 2.6 million years ago to the present day (yup: according to some experts, we're currently living through another).

11. Contrary to Popular Belief, You Won’t See Frozen Mammoths Suspended in Glaciers.

The mummified bodies of these great, extinct mammals are usually only found covered under frozen sediment and not—as many assume—floating inside glaciers.

12. Not All Glaciers Dwell Near the Poles.

Glaciers can be found on every continent but Australia (although New Zealand has some) and many “live” closer to the equator than one might expect—Mexico’s elevated areas are home to 24 [PDF] while the Ecuadorian Andes also have a few.

13. We Can Thank Glaciers for Something Called “Rock Flour.”

Fairsing, Wikimedia Commons // Public Domain

This stuff generally looks like earthy sawdust. As glaciers grate along the earth’s surface, they’ll grind bedrock into a fine, powdery substance. When this rock flour enters a lake, something magical takes place. Since it’s too fine to sink, the material may get suspended and turn the water turquoise blue.

14. Some Glaciers Look Blue Because That’s the Only Color Glacial Ice Can’t Absorb.

Unlike red and yellow lightwaves, blue light can penetrate snow and ice, thus creating that cool shade of winter wonderland azure.

15. Ancient Glaciers May Have Once Dotted Mars.

The red planet’s surface is rife with canyons, but did long-gone glaciers have anything to do with their creation? Some scientists think so. Last year, their theory got a major boost when a mineral called jarosite was identified along the walls of an enormous canyon known as Ius Chasma. On Mars, jarosite is created by reactions with water, usually through evaporation. But there was no way that a puddle was evaporating 3 miles up a cliff face. It’s believed that a glacier picked up some sulfur, and then as the sun melted the ice along the edges, the water reacted with the sulfur to produce jarosite.

16. Glaciers Occasionally Form Over Active Volcanoes.

In 1996, the Grímsvötn volcano of Iceland violently erupted despite the fact that it had been buried by roughly 2000 feet of glacial ice. Upon melting through this, a flood of epic proportions was triggered—one that caused $50 million in damages.

All images courtesy of iStock unless otherwise noted.