Geology+Botany =Geobotany

The geology of Ohio can be loosely divided into two parts. The western part of Ohio is dominated by limestone with pockets also containing dolomite which is a magnesium variety of limestone. Most of Ohio that is covered in limestone is flat because limestone is a soft rock and can be worn down relatively easy (Forsyth). Comparatively, the eastern half of Ohio is made up of sandstone with shale making up the layer beneath that. Sandstone is a much more resistant rock than than limestone, making the topography of eastern Ohio have steep sided hills with carved out valleys in rare areas that erosion has succeeded (Forsyth). 

The reason behind the difference in the western and eastern halves of Ohio is not complex. The original rock layer in Ohio was made up of a thick layers of limestone frosted by with shales and eventually topped with sandstones. The strata was then tilted to form a low arch (Forsyth). The arch was ultimately created as a product of all the pressure that built up. This arch created the original Appalachian mountains. Erosion has exposed the limestones where the peak used to be in western Ohio. The sandstone hills created by the arch still stand today in the Cleveland region. The erosion of this arch was mainly done by a preglacial stream called the Teays pronounced ‘Taze’. The erosion of the streams were only stopped by glaciers in the Ice Age (Forsyth).

Pleistocene glaciers invaded OH a few hundred thousand years ago or less. The steep-sided sandstone hills of eastern Ohio slowed down these glaciers, and made it so the glacial boundary does not extend further south than Canton (Forsyth).

A relatively rough sketch of the glacial boundary that extends across Ohio

A mixture of sand, silt, clay, and boulders was deposited by the glacier and is referred to as till. Till covers most of glaciated Ohio. Till also comes in the form of sand and gravel deposits, but this occurs only in special areas of Ohio. In western Ohio till is mostly composed of lime and clay. In contrast, eastern Ohio contains barely any lime and clay (Forsyth). 

Western Ohio plains contain limey substrate and clayey till. This makes the soil almost impermeable, very high in lime, poorly drained and has little to no aeration within the soil (Forsyth). However, in areas where the soil is not too thin, the soil is very high in plant nutrients. In eastern Ohio soils are composed of very acidic low nutrient substrate, that tends to be very dry on the tops of the sandstone hills (Forsyth). 

Five species of trees and shrubs that tend to be limited to areas with limestone or in limey areas are: Redbud (Cercis canadensis), Hackberry (Celtis Occidentalis), Blue Ash (Fraxinus quadrangulata), Chinquapin Oak (Quercus muehlenbergii), and Hop Hornbeam (Ostrya virginiana).

The above image is a  Blue Ash, Fraxinus quadrangulata, growing within limey substrate in Batelle Darby Creek Metropark.

A young Chinquapin Oak, Quercus muehlenbergii, found in Battele Darby Creek Metropark


Hop hornbeam, Ostrya virginiana, also discovered in Batelle Darby Creek Metropark


Some species of trees that are great representatives of high lime, clay rich substrates are as follows: sugar maple (Acer sacchurum), beech (Fagus grandifolia), red oak (Quercus rubra), shagbark hickory (Carya ovata), and white oak (Quercus alba).

On the opposite end of the spectrum some species of trees/shrubs that have a distribution generally limited to sandstone hill of eastern OH include: chestnut oak (Quercus Montana), sourwood (Oxydendron arboreum), scrub pine (Pinus virginiana), pitch pine (Pinus rigida), and hemlock (Tsuga canadensis). 

The major determinant for the distribution of sweet buckeye is that it does not occur anywhere within the glacial boundary. Additionally, the sweet buckeye does not grow anywhere as far north that the glacial boundary extends into(Forsyth). Contrastingly, the hemlock exists in unglaciated eastern Ohio and does grow far not past the glacial boundary. Interestingly, the Rhodendron (Rhodendron maximum) migrated down from the Appalachian highlands into the Teays River and came down south of the glacial boundary (Forsyth).

Cedar Bog that isn’t a Bog

Cedar Bog isn’t a bog it is a fen! On can think of a bog like a clogged bathtub where water flows in stays and doesn’t leave. However, a fen is more like a flushed system with water constantly flowing in and sometimes out (Cedar Bog Visitor Center). Cedar Bog is a norther arbor vitae bog where most of the plants that are found here are only native to bogs in northern Michigan (Frederick). Cedar Bog has a microclimate similar to that of one found in northern Michigan. Even during droughts there is a constant water flow in the fen. Water reaches the fen through surface runoff, but additionally and almost daily through groundwater hidden from the surface through glacial deposits (Cedar Bog Visitor Center). Water is able to flow through the sand and gravel hills that formed through the glacial deposits. 

On our way to the Fen!



At Cedar Bog we identified two different types of bright purple thistle, field thistle (Cirsium discolor) and swamp thistle (Cirsium muticum). These thistles belong to  the family Asteraceae.

Field thistle occurs in drier areas than its swampy relative. Field thistles can flower anywhere from June to October, this particular field thistle was seen flowering in early September. Field thistle leaves are white on their undersides  and have deeply lobed leaves (U.S. Forest Service). Young field thistle leaves and stems can be boiled and eaten (Illinois Wildflower Info).

Swamp thistle occurs in moist soil and tends to have not have leaves surrounding the flower head. Leaves of this thistle also have white fuzzy undersides similar to the field thistle (Field Biology in Southeastern Ohio). The marsh thistle can be eaten in a similar fashions the field thistle, but  additionally the seed fluff of this plant can be used as a tinder if you’re in a crunch (Natural Medicine Herbs). 

Swamp thistle hanging out with a bumble bee


Works Cited

 1974 Ohio Journal of Science article by Clara May Frederick

 Jane Forsyth, 1971 article “Geobotany”