The Tri-State has been blessed by Ice Age creation of the Ohio River.  It served as a major commercial artery in the early and mid-1800’s, transporting grain and livestock to the Mississippi River and down to the port of New Orleans.  In the 1830s, with the construction of the Miami & Erie Canal, Cincinnati became the primary center of processing and trade on the Ohio River.  Cincinnati’s population went from less than 10,000 residents in 1820 to over 115,000 residents by 1850.  This spurred the creation of other industries.  The local meatpacking industry gave rise to Procter & Gamble, which used the byproduct lard to make soap.  Machine tool operations located in the Mill Creek Valley and along the Miami & Erie Canal, where they used the flowing water to power their plant equipment.  The region’s clay soils fostered many brick-making establishments and the world-renowned Rookwood Pottery.  The region’s solid industrial base, burgeoning work force, and growing population has justified the construction of railroads, Ohio River locks and dams, state and interstate highways, and the August 1944 opening of what is now officially titled the Cincinnati/Northern Kentucky International Airport.  Better known as CVG, the airport is a prime example of regional collaboration because it is located in Boone County, owned by Kenton County, and attuned to the needs of more than a dozen counties in the Tri-State region.

North of the Ohio River, in areas underlain by deposits of Wisconsinan and Illinoian glacial drift, valleys are present near the major streams.  Areas of older or no drift sheets, the landscape is more deeply dissected by streams. The steepest slopes are located below Cincinnati along the Ohio River, where the river impinges and undercuts a valley wall.  This cut bank consists of soft Kope shales capped by more resistant limestones, which form bluffs with even greater slopes.  Some of the valley sides of the Licking River have comparable slopes for the same reasons.

In contrast to the deeply dissected topography described above are the poorly drained flat uplands of Clermont and southeastern Warren counties.  These areas are developed on the Illinoian till plain, which has had about 300,000 years for weathering to smooth and flatten its original glacial topography.  The much younger Wisconsinan drift sheet, no more than 19,000 years old, commonly has a gently rolling topography and much better drainage.  Both the younger and older drift sheets have modified the Tri-State’s terrain by filling its deep valleys with till and outwash.

Upland elevations across the region are uniform, ranging from about 825 to 900 feet above sea level.  The highest elevations occur in northern and southeastern Warren County on scattered outliers of Silurian carbonates, which stand 35 to 55 feet above Ordovician sedimentary rocks.  The local relief – the difference between the highest and lowest elevations in a county – is also restricted, averaging about 530 feet.  In the Tri-State area and across the Cincinnati Arch, these upland elevations define a regional erosion surface described as the Lexington Peneplain.

Geology and hydrology have molded the landscape and driven the growth of our geographically gifted region.  The OKI Regional Conservation Council is dedicated to preserving the benefits of our dynamic geological history.