I really enjoy stopping along roadsides to look at rocks. I don't know much about geology but love to collect cool-looking rocks. I've been learning some things reading your blog and want to get a bit more serious about geology. What tools and books do you recommend?
Fred Armens,
Chicago
Fred,
Good idea to have the basic tools in your vehicle- you never know when you'll want them. These would include a rock hammer (not a carpenter's hammer!) and a hand lens. You'll want eye protection when you use the hammer. A geology guide book to the areas you visit is also a good idea. A geologic map is always a good idea to have handy. If you are in an area where there are surface deposits like ash layers or lake beds, a gardening hoe is useful to scrape at exposures so you can see the layers better.
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| Chisel style |
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| pick style |
Rock hammers- These are made for bashing rocks. The idea is to break a hand sample off of an outcrop, or to break open a stone so you can better examine the fresh rock inside. Rock hammers come in two basic styles. Some have a chisel-shaped end, and others have a pointed pick end. The pointed end is nice for sticking into a small crack to help pry a rock loose. The chisel end is better for splitting fractures in rocks. Both work fine; it is the hammer head that you will use 90% of the time anyway. Get a rock hammer that is heavy enough to smack a rock. You might find a mason's hammer in a hardware store, but these usually have short handles that don't give you much leverage when you swing it. There is a good description of rock hammers on this wikipedia page: http://en.wikipedia.org/wiki/Geologist%27s_hammer. Pay attention to the discussion of hammer weight. Don't forget the safety glasses! Sharp chips or dust is no fun in your eye. If someone else is swinging that hammer, keep your distance and don't watch them!
Hammers are often placed in outcrop photos to give a sense of scale. So, here's an old geology joke: How do you know a person is a geologist? They have more photos of their rock hammer than the spouse and kids!
Hand lens- By this I mean a jeweler's loupe, not the magnifying glass Sherlock Holme;s uses to read fine print and look for clues. Use your lens to look closely at a rock to see the mineral grains or fine details in the rock. Or pick a sticker out of your hand. These lenses are held right up against your eye, with the rock you are examining very near the lens. You want a 10 power (10x) lens fro most usage. People who want more detail will find a 14x lens useful.
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How to use your hand lens. First, look at the rock without the lens. See something tiny and interesting? Then mark it with your thumb, place the lens over the flashing mineral crystal or whatever you saw, and bring rock and lens to your eye. You will want plenty of light, so this method works best outside in natural light, and with the sun shining over your shoulder- turn your back to the sun.
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| First, spot what you want to more closely examine... |
Guide books- In an earlier post I mentioned some of these. Especially useful to the layperson are the Geology Underfoot and Roadside Geology Series by Mountain Press Publishing Company. There are many other geology field guides written for a popular audience. Search the web to find something in the area you are interested in. Good idea to include 'geology field guide' in your search terms.
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| Then bring lens and rock up to your eye. |
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| Geologic maps remind me the crazy quilts my wife makes. |
Road map- get a good one. Your field guide may send you off on minor dirt roads that aren't shown on state-wide maps. There are topographic gazeteers to many states. Check the offerings by DeLorme.
'Small scale' vs. 'large scale' maps- The larger the scale, the more detail. I know this confuses people, it did me once upon a time. Map scales are given in fractions: 1:24,000 means 1 inch on the map = 24,000 inches on the ground, or 2,000 feet. 1:150,000 means there are 150,000 inches on the ground to one on the map ( that's 2.37 miles per inch). So, to remember which is 'small scale' and which is 'large', think of the fraction. Would you rather have 1:2 of pie, or 1:5? I don't know about you, but I'd rather have 1/2 a pie than only a fifth!
