Geobotany Essays based on this Article
- The geology of Ohio can be divided into two main parts: carbonate (mostly limestone and dolomite) and siliceous (mostly sandstone and shale) rocks, the western part being carbonates and the eastern siliceous. The carbonate rocks here formed when Ohio was a shallow tropical sea in the Paleozoic. The rocks are relatively susceptible to erosion, particularly via acid rain. Additionally, the majority of the glaciated parts of Ohio are carbonates. We are left with relatively flat, low-lying land. Our siliceous rocks, consisting of sandstones and shales, form deep valleys and mountains. The sandstone is much harder to erode, however the shale erodes easily and forms deep valleys in areas where it is not capped by sandstone.
- Originally we had carbonates overlain with shale overlain with sandstone. Due to uplift (Appalachian/Alleghenian orogeny at end Paleozoic) and erosion, the siliceous rocks are exposed in Appalachia and eastern parts of Ohio, and carbonates are exposed in the western glaciated parts of Ohio. This uplift formed an anticlinal “arch” of rock strata in Ohio with its apex in northwestern Ohio. Much of the erosion on the carbonates of western Ohio and the siliceous rocks of eastern Ohio was done by the Teays river, which flowed starting about 200 Ma and was stopped by Pleistocene glaciation a few hundred thousand years ago.
- The sandstone hills are very resistant to a lot of things, including glaciers. Their presence significantly slowed glacial encroachment and caused a pretty clear boundary across Ohio.
- Glacial till is varying sediments that are carried and deposited by glaciers. In glaciated Ohio, till occurs pretty much everywhere and consists of unconsolidated sediments that vary in composition based on the surrounding geology. Thus, the western part of Ohio has till mainly composed of clay and carbonate while the eastern area has very little. Although, along the boundary (sandstone hills) has the highest concentration of clay and carbonate sediments in Ohio.
- Based on the information I just gave, it is easy to determine basic information about the substrates available in these areas for plants to grow. That being said, in the western part of Ohio the substrate is very limey and clay-ey, with a less acidic pH. This creates a fairly impermeable soil, so water tends to sit on top of soil during wet times and the soil dries out a lot during dry times. The soil is very nutrient rich in these areas however. Additionally because of the limestone bedrock, there are cave and cavelet systems that much water drains into causing a drier soil. In eastern Ohio, the substrate is acidic due to the sandstone. Additionally it is very permeable, allowing for adequate water flow and drainage, however it is less nutrient rich. In the areas which have glacial gravels (which are very permeable) the oxygen content varies by elevation. In higher elevations it is drier and therefore has more oxygen, in lower elevations it is the opposite and can become very saturated with water.
- Five species that tend to live in high lime and clay areas are: redbud (Cercis canadensis), chinquapin oak (Quercus muehlenbergii), fragrant sumac (Rhus aromatica), hackberry (Celtis Occidentals), and blue ash (Fraxinus quadrangulata).
- Five species that live in very high lime areas like the boundary between glaciated limestone and sandstone are: red oak (Quercus borealis), sugar maple (Acer saccharum), beech (Fagus grandifolia), and shagbark hickory (Carya ovata).
- Five species that tend to live in acidic, sandstone areas are: chestnut oak (Quercus montana), blueberry (Vaccinium angustifolium), hemlock (Tsuga canadensis), sourwood (Oxydendrum arboreum), and mountain-laurel (Kalmia latifolia).
- Sweet buckeyes are only found south of the glacial boundary while eastern hemlocks are found both north and south of it. Rhododendrons are associated with the old Teays river system.
Cedar Bog (Not a Bog)!
- Despite its name, Cedar Bog is not a bog, it’s a fen. Fens have drainage/water flow while bogs don’t. Additionally, due to the surrounding bedrock being limestone and that some of the water flow comes from groundwater and nearby springs, the water becomes alkaline to neutral in pH allowing sedges to grow all over the place!
- Two plants with red fruits! Spicebush (Lindera benzoin) and Jack in the Pulpit (Arisaema triphyllum).