My fictional Myers Ridge has sinkholes. Oh my.
Since childhood, I have been fascinated with sinkholes, the idea of bottomless pits, and traveling in time. My stories touch on these fascinations, along with lightning strikes, the wonders of electricity, the mysteries of crystal rocks, and the uncharted powers of the human mind.
My stories take place in northwestern Pennsylvania, based on the topography of Erie, Crawford and Warren counties. I live in Erie County (shaded blue on the attached Pennsylvania map above), lived in Crawford County as a child, and travel throughout Warren County often, so I know the topography of these areas well.
Although PA is a high-risk state for sinkholes (also called swallow holes), none of the aforementioned counties has any that compare to the ones in the riskiest areas in PA: the limestone valleys through central PA—around State College and from the Maryland line up through Harrisburg and east to Allentown and Lancaster.
Still, sinkholes happen in the northwest part of the state when empty oil beds and coalmines collapse, and when acidic rainwater and groundwater dissolves the carbonate rocks beneath us. And that is the threat I give to my fictional Myers Ridge.
The land there us based on land composition not far from my backyard and is karst topography, albeit small in area. As you can see in the two photos above, karst topography can have many sinkhole depressions sculpted in the landscape. Since the bedrock in karst areas is typically soluble limestone or dolostone, chemical weathering has already occurred over thousands of years to produce large voids, known as cavities or caves. From these large voids come subsidence sinkholes and collapsing sinkholes.
With subsidence sinkholes, the fractures in the bedrock grow with time from the rainwater’s chemical reaction with the rocks. As the voids grow, groundwater flow increases, dissolving continues, and land slowly drops as the bedrock dissolves away.
Collapsing sinkholes happen when void spaces become well developed, the arch becomes too large to support the overlying soils, and an abrupt collapse occurs. Factors usually include the water table dropping which results in soils becoming very saturated and dense. Eventually the cavern’s roof cannot support the weight of the overlying material and the cavity collapses instantaneously. Yes, instantaneously. The formation and release of collapsing sinkholes can happen in a matter of seconds. They can destroy entire houses and swallow portions of roads or anything else that sits above the unstable ceiling.
Despite the dangers of sinkholes swallowing people, places, and things, my stories wouldn’t be mine if it didn’t include some science fiction and fantasy elements. Time travel is a major theme because it is so fun to imagine and write about. Of course, time travel comes with repercussions, which adds greatly to the stories.
So, enough about sinkholes. It’s time to get back to work. The climax and denouement of falling in a sinkhole await my characters.