Geology

Geology is the study of the composition and physical properties of rocks, minerals, gems and other related earth materials, including diamonds and crystals. Scientists gain an understanding of the Earth's history by studying its composition.

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Diamonds are some of the most brilliant and expensive natural features Earth has to offer. This collection of images displays diamonds in all their uncut and polished shapes and sizes. Obligatory pictures of very large diamonds are included of course.

By HowStuffWorks.com Contributors

One grows from the ground and one from the ceiling, but sometime's it's hard to remember which is the stalactite and which is the stalagmite. How do they get there, anyway?

By John Fuller

Mountains might look like they're stoic and still, but research shows otherwise. Massive ones, like the Matterhorn, are moving all the time, gently swaying back and forth every few seconds.

By Richard J. Sima

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There are caves all over the world, but some are in places that are hard to explore — hidden by rocks, ruins or even under ice. We've found seven secret caves you probably never knew existed.

By Stephanie Parker

Waterfalls are mainly reliant on precipitation to keep flowing. Here are six famous waterfalls that slowed to a trickle when drought set in.

By Laurie L. Dove

Cinnabar's bright-red pigment has been used in jewelry, pottery and makeup for millennia. But cinnabar is also the primary ore for mercury, making it a dangerous mineral if the particles are inhaled.

By Allison Troutner

This ancient rock adorns King Tut's coffin and the Sistine Chapel. And at one time it was more precious than gold. What is it about this deep blue rock that has drawn us in for centuries?

By Carrie Whitney, Ph.D. & Austin Henderson

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Nutty Putty Cave, near Salt Lake City, Utah, was discovered in 1960 and sealed up forever in 2009. But why?

By Dave Roos & Austin Henderson

Carbon-14 dating is something that you hear about in the news all the time. Everything from mastodons to the Shroud of Turin has been dated using this technique! Learn about how carbon-14 dating works and why it is so accurate!

By Marshall Brain

When it comes to fossils, specimens like Sue the Tyrannosaurus rex grab much of the attention. And while Sue is a staggering 67 million years old, she's a new kid on the block, compared to some of the oldest fossils ever found. What's older than Sue?

By Jonathan Atteberry

Crack open any science textbook and the authors will tell you that such things don't happen. So how did a couple of paleontologists and an acid bath turn that widespread belief on its head?

By Robert Lamb

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Birds then dinosaurs or dinosaurs then birds? It's a lot like the chicken-and-egg question, only with paleontologists. Who's arguing what these days, and what are they citing as evidence?

By Robert Lamb

Sand dunes belch, moan and hum. They roll across the desert, seeking out new locales. You might even say they breed. It's no wonder people call these giant sand formations lifelike.

By Debra Ronca

Hollywood makes T. rex seem fast and agile, but some scientists think it was a scavenger, like a vulture. So which was it?

By Tracy V. Wilson

Researchers think the Chicxulub crater was caused by the massive asteroid that also killed off the dinosaurs 66 million years ago. What else do we know about this peak-ring crater?

By Mark Mancini

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Scientists believe that water pressure kept many dinosaurs from swimming. But does that mean that none of these massive animals took a prehistoric skinny-dip?

By Tracy V. Wilson

Ever since its discovery in 2000, a dinosaur fossil named Leonardo has held the interest of paleontologists the world over. A 3-D model of the animal even toured the world. So what's the big deal?

By Tracy V. Wilson

Dinosaur eggs and the embryos inside can teach us a lot about dinosaur reproduction and behavior. But how do scientists get the rocky embryos out from the equally rocky shells?

By Tracy V. Wilson

When they discover dinosaur remains, how do scientists know whether they found a male or a female? Would you believe it all comes down to one bone?

By Tracy V. Wilson

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Fossils tell a story, much like the clues at the scene of a crime. Researchers look for evidence and paleontologists study that evidence to answer questions about the past.

By Tracy V. Wilson

We all know the cartoons of prehistoric people running from dinosaurs aren't realistic. But many animals living today have ancestors from that time.

By Tracy V. Wilson

The end of Earth will likely come about because of the sun in our solar system. This much you might already know, but we actually have an approximate date.

By Robert Lamb

Diamonds are beautiful and popular - but not everyone can afford these gems. While man-made versions are less expensive, most lack the luster and brilliance of the real thing, except moissanite. See how it compares!

By Melissa Russell-Ausley

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Diamond engagement rings. Diamond anniversary bands. Diamond earrings and necklaces. And now, the right-hand diamond ring! The four Cs -- cut, clarity, carat and color. Find out what the fuss is all about.

By Kevin Bonsor

Countless movies and television shows depict quicksand as some kind of living creature that sucks its victims down into a bottomless pit, never to be heard from again. Well, you can't believe everything Hollywood tells you.

By Kevin Bonsor