The unique geology and microclimate of Hocking Hills State Park

Ohio’s tourist hotspot is also a natural wonder

By Alicia Szczesniak

Deep in the heart of Southeast Ohio lies Hocking Hills State Park. The park spans over 2,000 acres, and is home to a variety of different flora, fauna and formations. 

But, much of this is unique to the region. 

Among Hocking Hills unique aspects is its Black Hand Sandstone. Black Hand Sandstone is a type of sedimentary rock that is best known for its red, gray and brown stripes and swirls in different shades. Like other types of sandstone, it is formed through the deposition and compaction of sand grains, often from marine environments like seas and rivers. 

Now, what makes Black Hand Sandstone so unique is the fact that it is only found in Ohio, in a long strip reaching up from Southeast Ohio to the Mansfield area. The stone forms the towering cliffs and rocky outcrops that are so commonplace in Hocking Hills, as well as other areas such as Blackhand Gorge State Nature Preserve in Licking County. 

Black Hand Sandstone in Conkle’s Hollow

They, like many other rock formations, were formed through a steady process of uplift and erosion. Uplift, or the pushing upward of landforms through tectonic movement, was occurring heavily in the Appalachian area, where Hocking Hills is located. This created the hills and mountains of the range. As this was occurring, water flowed through the area, slowly eroding awa

y at the sediment. This would only increase as the glaciers pushed southward, stopping just a few miles from Hocking Hills. However, the glaciers would block anywhere for the groundwater or meltwater to go, inundating the small stream valleys with more water, allowing for greater erosion rates, carving deep hollows and gorges. 

Once the glaciers receded, though, stream erosion and weathering have continued to slowly strip away sediment, continuing to shape the landforms into the structures we see today. 

But it is not just the geology of the region that is fascinating. The gorges and hollows of Hocking Hills have created tiny microclimates more akin to climates located further north. 

As the glaciers moved through, they picked up plants and seeds and transported them to the region, which would eventually be pushed by meltwater into the streams and deposited along the way. 

One such example of this is the Eastern Hemlock (Tsuga Cadensis), which is typically found at more northern latitudes and higher altitudes. However, a pocket of them exists within the hollows and gorges of Hocking Hills. 

Upper Falls at Hocking Hills, carved by millions of years of erosion

But the odd thing about the Eastern Hemlock is that it thrives best in temperatures between 50°F and 70°F, as well as cooler climates. So, why do they thrive so well in summers with average temperatures reaching well above 80°F? 

The gorges are a major reason for this. Gorges, oftentimes, may be cooler than the surrounding landscape. This is for a few reasons. One, the amount of sunlight that is able to reach the bottom of the gorge is limited. This is because the trees and vegetation along the sides of the gorge create shade, disallowing as much sunlight from reaching the bottom. 

Additionally, daylight has a much narrower window of time to reach the gorge as compared to the surrounding area, as sunlight is unable to light up and heat up the bottom of the gorge unless it is shining nearly directly above it, leaving it in a state of perpetual shade for most of the day. 

Alongside this, cold air is typically denser than warm air, meaning that it sinks as warm air rises through a phenomenon called a convection current. Because gorges are lower than the surrounding landscape, cooler air will naturally gravitate towards it, creating a colder environment. Finally, the water from the streams flowing through gorges and the sandstone that makes up the cliffs and outcrops are notoriously poor conductors of heat. This means that when they are cold, they stay cold, helping keep cooler air within the gorge. 

Frozen waterfalls at Conkle’s Hollow on February 2, 2025. Despite temperatures reaching the low 50s, the cold air in the gorge kept the waterfalls frozen

As a result of these factors, gorges are able to create a perfectly cool environment for species that are generally found further north, such as the Eastern Hemlock. 

But it is not just the Eastern Hemlock that is found a little further south than its normal habitat. Another example is Sullivant’s Coolwort (Sullivantia Sullivantii). Sullivant’s Coolwort is a small plant with white flowers that is typically found in Wisconsin, Minnesota and Northern Iowa. However, the cool environment of the gorges of Hocking Hills created a perfect habitat for it despite its more southern latitude.

And organisms other than plants thrive in the miniature boreal forest of the Hocking Hills gorges as well. One example is the Blue-Headed Vireo, a small bird marked by a blueish head and a green back. They are commonly found in mixed forests, or forests where both conifers and deciduous trees grow together. However, the mixed forests it lives in are typically scattered across Canada and the Northeastern United States. But, they have been seen in gorges and other cold microclimates, such as the higher peaks of the Appalachian Mountains and the gorges of Hocking Hills. 

In fact, many birds, such as Winter Wrens and different types of Northern-dwelling warblers are seen (and heard) throughout the gorges, namely Conkle’s Hollow. 

Despite looking like the rest of Appalachian Ohio at a glance, the Hocking Hills region’s unique combination of native sandstone and non-native plant and animal life has fostered a microclimate more akin to the cool, humid boreal forests of the Pacific Northwest and Canada.

Wanna chat? Email Alicia at as589820@ohio.edu, or follow her on instagram @alicia_szcz.