However, now we're finding that is not true. Much of Ohio was seen as a safe place for landfills because of the presence of glacial tills - the soil, rocks and other material left behind by glaciers that covered much of the state during the last ice age, Christy said. While scientists once thought these glacial tills were nearly impermeable to wastes, the discovery of fractures in these tills is giving researchers second thoughts. Scientists have begun a collective effort to locate and describe underground fractures beneath Ohio counties. While comprehensive studies of this type have not been done outside Ohio, the researchers believe that other states which experienced the same type of ancient glaciation may well be affected in the same way.
Fractures are particularly important to the movement of water.
They recharge the underground water table, which supplies 800,000 private wells and more than 40 percent of the public water supplies in Ohio. But water that passes through fractures isn't purified in the same way as it would be if it traveled through tightly compacted glacial till, according to Christy. In another study reported in the special issue, researchers examined soil profile descriptions that have been published in Ohio county soil survey reports since 1900. The researchers were looking in these reports for descriptions that suggest the presence of underground fractures. But in reality, water will travel through fractures and cracks in the ground, essentially bypassing the compacted sediment and foregoing any purification.