Tuesday, March 11, 1997
You're not flooded? Thank glaciers
Ice put Tristate on higher ground

The Cincinnati Enquirer

While the deluge of '97 has pummeled a lot of the Tristate's low-lying homes and businesses, many more buildings have remained high and dry, thanks, simply and profoundly, to topography.

Unlike many river cities in the Midwest that grew in natural flood plains, most of Cincinnati and Northern Kentucky rest on high ground.

David Nash, professor of geology at the University of Cincinnati and an expert on floods and their effects on topography, said that the Ohio River simply can't get to where most of us live.

''It's too elevated, a river could never reach it,'' he said.

But why? For the answer, you have to go back to the Pleistocene epoch and the glaciers, those continent-sized ice flows that rumbled south from the Arctic, churning up our landscape. Their work eons ago made most of our area a pretty flood-proof place - at least until the next ice age.

In his summation of Cincinnati topography, ''A Recycled Landscape,'' the late Richard Durrell, a UC geology professor, described how three glaciers, the Kansan, the Illinoian and the Wisconsinan, reached the edge of what is today Cincinnati before melting and transforming the land.

About 2 million years ago, our area was an almost flat plateau, with a meandering river flowing north. The Kansan glacier stopped in Northern Kentucky, blocking that river and creating a giant lake in the area. After the glacier retreated, an ancestor of the Ohio River was born. It began to flow west, looping through what is today Norwood and on north to the Mill Creek and back south down a channel that is today the Great Miami River.

The river and water runoff cut deep ruts in the area's landscape, transforming the flat land into a series of plateaus. These plateaus, eventually through erosion many feet above the flowing waters, became the ''hills of Cincinnati.''

Today, most of the Tristate lives in these areas. In Kentucky, Fort Thomas, Fort Wright, Villa Hills, Erlanger and other communities rest on this high foundation. In Ohio, most west side neighborhoods plus Clifton, Walnut Hills, Mount Lookout, Hyde Park and other city communities and suburbs are high above any flood danger.

The next glacier, the Illinoian, which came about 400,000 or 500,000 years ago, created lakes in Norwood and downtown Cincinnati, making much of the soil in those areas thick with clay.

The most recent glacier, the Wisconsinan, about 50,000 to 80,000 years ago, created our modern landscape. The glacier backed up the lakes and forced water through the Anderson Ferry gap, which until then had been dry. The Wisconsinan glacier also deposited tons of sand and gravel on the former lakebed of what was to become downtown Cincinnati, the Mill Creek and Covington-Newport area.

Over the centuries, that sand and gravel washed away from much of the Mill Creek Basin and the Northern Kentucky lowlands. But this ''Wisconsinan Terrace,'' as it is called, remained in the downtown Cincinnati area, adding about 70 feet to the elevation of the area. The flood plain in this area is about 490 feet above sea level, according to Professor Nash, and the Wisconsinan Terrace that is downtown is about 560 feet above sea level.

''All that Wisconsinan Terrace, that's why it's such a great location,'' Mr. Nash said.