When is brown not brown?
Today's educational post has to do with colors. One duty of an archaeologist is to describe the soils they're digging in. I used to think there was "dirt" and "sand", but boy was I wrong. Fortunately, there's soil surveys done by qualified government folks to make our job a bit easier. There's also a booklet you can get that has decriptions of all the aspects of soil that you could ever want to, or need to, know. And someone at work made an even easier cheat sheet for us.
Our main tool, however, the Munsell Soil Color Chart, based off of the work of Albert Henry Munsell. In a nutshell, the Munsell Chart tries to put some uniformity into soil colors, because we don't see things the same way. So, when you say "brown", you are assigning a number to it. Actual "brown" in the Munsell Color Chart is 10 YR 4/4. You might think something is brown, then when you hold the dirt to the chart, it's actually 10 YR 4/1, which is a greyish brown (I don't remember them all). As soils get more red, you try a different page in the book (like, say 5 YR or even 5 R). Not too difficult.
Of course, there's still a bunch of subjectivity. Sometimes, a dirt can be sort of in between 2, or even 4 different color numbers. Dirt will change colors as it dries out, and the ambient light can make a difference as well. And then there's mottles...but this is now getting dry. If you have clicked on the links, then you can see that a Munsell "book" as we call it costs a lot of money. I want one, but not at that price. We could have used one today, but we forget to bring one of the office copies, so we relied on the semi-complete 10 YR page that someone let me borrow and tried to make up what the reddish colors we had might be.
Our main tool, however, the Munsell Soil Color Chart, based off of the work of Albert Henry Munsell. In a nutshell, the Munsell Chart tries to put some uniformity into soil colors, because we don't see things the same way. So, when you say "brown", you are assigning a number to it. Actual "brown" in the Munsell Color Chart is 10 YR 4/4. You might think something is brown, then when you hold the dirt to the chart, it's actually 10 YR 4/1, which is a greyish brown (I don't remember them all). As soils get more red, you try a different page in the book (like, say 5 YR or even 5 R). Not too difficult.
Of course, there's still a bunch of subjectivity. Sometimes, a dirt can be sort of in between 2, or even 4 different color numbers. Dirt will change colors as it dries out, and the ambient light can make a difference as well. And then there's mottles...but this is now getting dry. If you have clicked on the links, then you can see that a Munsell "book" as we call it costs a lot of money. I want one, but not at that price. We could have used one today, but we forget to bring one of the office copies, so we relied on the semi-complete 10 YR page that someone let me borrow and tried to make up what the reddish colors we had might be.
posted by jlowe | 5:18 PM
2 Comments:
If nothing else, I learned about dirt today. Thanks, jlowe!
i thought you were going to get it tattooed next to your poison oak/ivy tattoos...?
-chew
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