1) If the geology of Ohio is not monitored t0o closely then it can be divided into two different parts. Theres Western Ohio and Eastern Ohio. In Western Ohio you have erodible limestone and dolomite due to 200 million years of erosion on flat level landscape. As well as, a rock type that is nonresistant in the humid climate. In Eastern Ohio you have erodible shale capped by erosion resistant sandstone. Due to this there is deep valleys with steep sandstone hills.
2) The oldest rocks were limestone, then sandstone then shale. Most of the erosion that occurred was in result to a preglacial stream named Teays river. This river was present in Ohio for 200 million years and therefore, curtailed the advance of the glaciers of the Ice Age less than a million years ago.
3) When the Pleistocene glaciers invaded OH the steep-sided sandstone hills and flat limestone landscapes helped to slow down the glaciers.
4) Glacial till is an unsorted mixture of sand, silt, clay and boulders which was accumulated by the melting ice and the sand and gravel material from the glacial meltwater. In Western Ohio, the glacial till is rich in lime and clay. While in Eastern Ohio, the till has very small amounts of lime and clay.
5) In Western Ohio the most common substrate is lime and clayey till that provides impermeable soil, high in lime but low in drainage and not aerated properly. Therefore, water will not soak into the soil fast and will create low oxygen availability during wet periods and bad droughts during dry spells. The soil on the limestone is typically very shallow, high in lime and rich where the soil is not too thin, but will stay dry because of too much drainage of natural solution.
In Eastern Ohio however, there is permeable sandstone bedrock that produces a high amount of acid with low-nutrient substrate that is dry on top of hills. The acid in this region provides a supply of moisture that is continuously available because the water comes from springs that is deep in the valleys and have not been sun warmed. The shale below the sandstone also produces acid low-nutrient substrate, but it is impermeable causing water to run off rather than soak in.
6) Redbud, Red Cedar, Blue Ash, Hawthorn and Fragrant Sumac, are 5 species of trees that are usually limited to limestone or limey substrates.
7) Sugar Maple, Beech, Shagbark Hickory, White Ash and Pin Oak are 5 species of trees that are usually limited to high-lime and clay-rich substrates that are developed in the thick glacial tills of western Ohio.
8) Chestnut Oak, Sourwood, Scrub Pine, Pitch Pine and Hemlock are 5 species of trees that are usually limited to sandstone hill of eastern Ohio.
9) The major determinant of the sweet buckeye is climate and the Hachured line between limey and sandstone and having issues with repopulation. Looking at Hemlock on the other hand that is also present in un-glaciated eastern Ohio is more abundant. It is more widely distributed because of cool, moist environments that are found in deep valleys cut into sandstone or even in cool, moist north facing valleys. Lastly, the major determinant of rhododendron when looking at the map of the valleys in the ancient Teays system, you will notice that the Rhododendron lived and still lives in the Appalachian highlands and migrated down through the preglacial Teays River system.