Oil from Troubled Waters? (GM-28)
Not all that is black and slippery is crude oil. Many people have become startled and excited at finding what they think is a petroleum seep in a marshy area, in a spring, or perhaps oozing from an accumulation of dead leaves on some remote corner of a farm. Decaying vegetation produces a variety of compounds called humic and fulvic acids, which at first may look and feel like crude oil. These organic acids are the first stage of the long process in the formation of hydrocarbons. Not only do humic acids look like oil, but very fine clay particles and water in a mixture called a colloidal suspension can produce a variety of dark slippery fluids that look remarkably like Jed Clampet's "bubbling crude."

Petroleum seeps occur in Indiana, but none are considered to indicate recoverable oil at depth.

Our Hoosier State Beneath Us: Geomorphology