Learn about geology on walk

What does geology have to do with the landscape and buildings of downtown Geneva and St. Charles?

It delineates whole histories embedded in ornamental stone, describes the formidable forces that architects and engineers must contend with when building roads, bridges, and habitable structures, and gives you a better sense of the links between art and science.

These themes will be addressed when Raymond Wiggers, director and founder of the Natural History Exploration Guild, will offer a "City of Stone and Clay" walking tour Sunday in St. Charles and Geneva.

This is part of a series of educational hikes and will take place from 1 to 3:30 p.m.

This event is open to the public by prior payment and registration. No prior experience in geology is necessary. For details on tour costs, visit the Guild Web site at www.nheg.org/Tours.html.

The hike features a close look at architecturally notable buildings and other aspects of the built environment, including ornamental terra cotta, brickwork, and both locally quarried and exotic decorative stone -- some of which is an astounding 3.6 billion years old.

Participants will also learn about the two great chapters of local geologic history -- the Silurian Period of 420 million years ago, when the region's bedrock was formed in a shallow tropical sea, and the Ice Age, which has powerfully remolded the landscape of the Fox Valley and the rest of northeastern Illinois.

Wiggers is the author of the field guide, "Geology Underfoot in Illinois" and three other natural-history books.

The Natural History Exploration Guild, founded in 2004, is a membership-based educational organization dedicated to enhancing the public appreciation of the biological and Earth sciences, and their links to human culture.

For more on the Guild, visit www.nheg.org.