The Smithsonian National Museum of Natural History is currently featuring a new exhibit called Dig It! The Secrets of Soil.
What is Soil? Here's a handy definition I learned in graduate school -- Dirt is dead. Soil is alive. Soils are dynamic ecosystems filled with living things like insects, worms, bacteria, and fungi.
How do soils form? Check out this handy chart to learn more about the five soil formation factors: Climate (Is the surrounding area rainy or dry? Salty or devoid of minerals?) , Biota (Which plants and animals live and use the soil?), Slope (Did the soil form on a mountainside or in a valley?), Bedrock (What kind of rock has contributed to the soil?) and Time.
How many different types of soil are there? "Scientists recognize about 70,000 soil types in the United States alone ..." according to Paul Reich of the Natural Resources Conservation Service of the USDA, as quoted in this exhibit. His Global Soil Regions Map is shown on the NRCS Soils Website.
Check out the Educators Activity Page for fun ways to learn about soils both at the museum and at home. Learn More about soils by visiting these websites recommended in the exhibit.
(My thanks to Soils Professor Dan Richter for letting me know about this exhibit!)