How were Millennium Park lakes formed?
The Millennium Park is rich in minerals used in construction, including gravel, sand and gypsum. As a result, considerable mining has occurred in the area. Over the years, much of the sand and gravel has been dug out from the surface, creating holes known as quarries. The quarries have since filled with groundwater. These watery areas were enlarged and combined to form lakes for boating, fishing and swimming.
