Geology And Geophysics

A Guide to Backyard Geology



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One of the first things a geologist needs to learn is how to identify rocks right?

Not really.

Geologists have to train their eyes to visually filter their surroundings, and digs to find specimens. This way, geologists don't waste time digging or searching through rubble in an area where they won't find anything.

Anyone can learn to visually filter. All you need is an idea of the landscape and a magic eye.

Let's start with the geological landscape:

1)Know where you stand.

What's beneath your feet will tell you a lot about the materials you'll find in any given area. Ask yourself is the ground low and boggy, or high and dry. Are there large stray rocks dotting the landscape, or are large areas of flat rock exposed from erosion?

2)Think about how the area may have developed into what it is today.

The laws of physics will help you out here. Say your standing between two hills and the ground is wet and boggy, chances are years of sediment along with plant and animal matter has washed into the low lying area. Screening and sifting dirt and mud from such a place will yield all kinds of cool things.

3)Let Mother Nature do all the really hard work.

The scenario in number two is a good start, but why not let nature do some of that sifting for you. Water always seeks its lowest point carrying sediment along with it. Both wet and dry stream beds are hot spots for finding rock specimens that are just waiting to be picked up.

Okay, now that you know about the lay of the land, let's learn how to acquire a magic eye.

If you've ever actually seen the image in a Magic Eye (ME) print or found Waldo you have some idea about how you can find a single image among a billion similar images. If not, I'll provide a web page at the end of this article where you can view ME. There are also Where's Waldo pages, but since some may cause a heart attack, you're on your own there.

Geologists use their magic eye to filter out ordinary rocks from specimen rocks. The process works on three principals:

1)Patterns

My favorite finds are fossils. In a fossil bed of Devonian Sea creatures I would expect to find trilobites, so I would looking for the distinctive beetle shape and ribbed patterns of trilobites. Unfortunately, by using such specific tunnel vision I might miss out on a perfectly defined brachiopod which looks like a nice fat clam.

To break away from tunnel vision when fossil hunting you have to train your eyes to look for patterns only found in living organisms. Symmetrical patterns are the identical on both sides of the organism; fold a picture of a human face in half eye to eye (this called the median line). It should line up fairly close on both sides of the page.

In asymmetrical patterns of plants alternate the height of branches extending from the median line. Think of a stack of letter Zs to imagine this pattern.

2)Color

Looking for color variations in the soil or rock will tell you about the geology and timetable of the area you're looking at. The Grand Canyon is the finest example of color variations, but if you're not in Nevada you can still understand this principal. Just make yourself a sandwich layered with mayo, meat, cheese, lettuce and tomato, cut it in half and there you go...layered color variation.

If you're digging in an area for perhaps, amber (the hardened sap of ancient trees), you would be looking for darker soil which indicates the dense organic material that would be found on an ancient forest floor. This kind of color variation would tell you this is spot to find amber.

3)Texture

While crystals generally have a smooth surface they're often overlooked because they are dirty, or have fused with other rock materials. When looking for texture generally scan to see what stands out as unusual. In a brook full of round pebbles a black lumpy piece of iron ore would stick out like a sore thumb, as would sharp shards of broken glass, so be careful where you step.

Now, the best way to work on magic eye development is to find things because like in the real Magic Eye once you've seen the hidden picture it will only take seconds to see it again and again.

Here are a few fun exercises to help you along:

1)Spread out a small bag of barley or grits and find the pebbles and or, darker colored grains.

2)Spread out a bag of stones on a tray and toss in a few small specimens, mix it up, and start searching.

3)Dissect owl pellets. They contain the teeny tiny bones of creatures owls eat. They can be ordered online.

But I do have to warn you... once you open the magic eye, you can never close it again. You'll always be on the look out, and you'll always find cool things.

Good luck

Magic Eye page: http://www.magiceye.com/faq_example.htm

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