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Soil Science Education
Every Soil Has A Story
The soil forming factors work together to form a soil profile. Like the profile of your face, a soil profile has features or layers. The layers in a profile are called horizons. Let's take a look at this profile. Can you see the different horizons here? This soil profile is from a creek bed in College Park, MD in the Chesapeake Bay watershed. When the soil scientists were studying this profile, they noticed deposits in the middle of this profile. Right in the middle of the profile, there was a black layer. When the scientists looked at this layer with a hand lens they could see that the black color was due to many tiny bits of charcoal. And they figured out that this charcoal was deposited in the middle of the profile about 300 - 350 years ago.
Why do you think there was charcoal in this soil horizon?
Where would charcoal have come from about 300-350 years ago? What was going on in the Chesapeake Bay region at about that time? Settlers were burning the forests to make room for farms. The residue from those forest fires flowed down into the rivers and creeks and eventually some of it was deposited right in this creek bed and became part of this soil profile. Let's take a look at the horizon below the charcoal layer. When the soil scientists were studying this horizon, they noticed these hard rounded objects. They figured that this horizon was deposited here about 400 - 450 years ago.
What do you think these rounded objects might be?
They are clam and oyster shells (as well as some pebbles rounded by washing down the river during flood events). What do you think was going on in the Chesapeake Bay about 400 - 450 years ago? The indigenous people would come to the Bay for their holiday feasts and they would party and eat lots of clams and oysters and this is essentially what was left over after the parties. These shells eventually flowed down into this creek bed and became part of the soil profile.
The last part of the story takes us to the beginning. The lowest two horizons in this profile are of an earlier soil that was buried under the river sediments of the newer soil. The buried soil shows structure, colors and other features that indicate it is many thousands of years old and was in a swampy area before the river changed its course a bit and began to bury it.
This is an example of how a soil can be a record of the history of the area around it and thus have its own story.
If you have a soil story that you wish to have published on this web site, please send the story, along with any photos or images to:
For more soil stories, head over to "Once Upon A Sandy Loam."
Soil Profile Image: Courtesy Ray Weil, PhD., University of Maryland
Every Soil Has A Story
- NASA Official: Eric Brown de Colstoun
- Webmaster: Brent Stees
- Curator: Izolda Trakhtenberg
- Page Last Updated: April 28, 2011