The Mysterious Mound in Split Rock (Pennsylvania)

The mysterious grassy mound at Split Rock. The rock formation is behind it, hidden by trees.

Hidden behind a veil of tall trees in deep Pennsylvania lies Split Rock, a gargantuan rock with a cleft in its middle.

We stayed at the nearby Split Rock Resort and Lake Harmony last month and took one day to visit this strange rock formation, which was created 300 million ago when glaciers swept across the land and also created Lake Harmony.

Drone view of Split Rock with the cleft near middle

The rock itself was fascinating, and you can access the top by climbing up a wooden platform. But another thing that caught my eye as we walked from the parking lot was an equally strange small hill or mound that lay to the side of the formation. It was almost dead center in a clearing, surrounded by trees.

It was also covered in grass, but not turf grass. Instead, I noticed Panicum virgatum (switchgrass) and another species that I at first thought was Schizachyrium scoparium (Little Bluestem).

P. virgatum spikelets

The P. virgatum had beautiful purplish spikelets, with purple fuzzy stigmas and orange anthers.

P. virgatum spikelet showing purple stigmas and orange anthers

The other notable species I found was something that I at first thought was S. scoparium. It had fluffy flowerheads and a similar habit to that species.

A.virginicus seedheads

But when I used macro on the spikelets, the first thing that was noticeable was the very long and straight awns. S. scoparium has awns, but they are noticeably bent, and I decided that what I was seeing was Andropogon virginicus, which is a robust species that is even common in disturbed areas.

For more on the spiketlets of the beautiful S. scoparium, click here.

A. virginicus spikelet. (A) Sessile fertile floret with long awn. (B) Sterile floret on a stalk. (C)  Disconnected raceme connection to the other spikelets.

I have no idea how this mound was formed, or even whether it is a natural formation or one that was man-made. When I was there and it was getting into dusk, the entire place felt dark and otherworldly, and I could not help but wonder whether some eerie rituals were held atop this grassy knoll. The somber lighting, dark forested location, and weird clearing would be perfect for some Hollywood horror film. 

If you ever visit this area in Pennsylvania, then take some time to get a glimpse of this mysterious mound with its trove of native grasses, and the riven rock behind it. Just don't do it in the dark!