Sinkholes are a geological phenomenon that have captivated the curiosity of many, including Lauren Bacchus, a member of the Asheville Sinkhole Group. This group, consisting of over 3,400 individuals in and around Asheville, North Carolina, shares a fascination with the mysterious chasms that appear sporadically in their city. Bacchus, who even owns a T-shirt dedicated to sinkholes, acknowledges the oddity of her passion but finds beauty in the impermanence of human-made structures that sinkholes symbolize.
The recent appearance of a sinkhole near a storm-damaged area on the outskirts of Asheville reignited interest in the group. With the region experiencing increased flooding and damage from extreme weather events like Hurricane Helene, sinkholes have become a pressing issue. These voids in the ground can range from small pits to massive craters, posing a threat to infrastructure and public safety.
Sinkholes can form rapidly or develop over time, either naturally or as a result of human activities that disrupt the underground water flow. Climate change-induced heavy rainfall exacerbates the formation of sinkholes, as seen in the uptick of sinkhole occurrences in Asheville. Road crews in the region have been kept busy dealing with the aftermath of these geological anomalies.
While some sinkholes, like the infamous Golly Hole in Alabama, make headlines for their size and impact, many go unreported, resulting in significant financial losses for affected areas. States like Tennessee, Kentucky, Florida, and Pennsylvania are hotspots for sinkhole occurrences due to their soft, porous bedrock.
Florida, in particular, has earned the title of the “sinkhole capital” due to the proliferation of sinkholes following major storms. Sinkholes are not only costly to repair but also pose challenges for homeowners, as many insurance policies do not cover sinkhole damage. Efforts to update disclosure laws and regulations regarding sinkholes have been ongoing in states like Florida and Tennessee.
Despite the challenges and dangers posed by sinkholes, residents of Asheville continue to show a fondness for these geological features. The sinkhole group in the city has grown in popularity, with members sharing stories and experiences related to sinkholes. From monstrous sinkholes swallowing parking lots to the closure of a beloved Waffle House due to sinkhole damage, Asheville’s residents have a unique appreciation for the quirks of their karst landscape.
As sinkholes continue to be a fascinating yet costly geological phenomenon in Asheville and beyond, the need for proactive measures to mitigate their impact remains crucial. With climate change exacerbating the conditions that lead to sinkhole formation, communities must be prepared to address these challenges to ensure the safety and stability of their infrastructure.
In Western North Carolina, and other areas with notably no limestone, sinkholes are mainly the result of human intervention – construction fill, bad plumbing, and choices made by developers and builders that result in water going places it shouldn’t. However they arise, sinkholes have an insatiable quality to them, often expanding in ways that make them difficult and sometimes impossible to repair. But they also create a sense of wonder and fascination – the feeling of peering into another time. By opening a window into a subterranean world of water, fossils, and caves, they offer a glimpse of what came before.
And, experts say, we might see more of them as a warming world makes big storms more common. Ernst Kastning, a retired geology professor who taught at Radford University in Virginia, said sinkholes are often a natural reaction to a sudden change, like torrential rain. They can form as all that precipitation flows downhill, such as via an underground cave system. “​​The water has to come out somewhere,” Kastning said.
After an intense downpour or sudden inundation, the land attempts to restore equilibrium, which often means water and soil move into inconvenient places. Geologists colloquially call this the earth’s “plumbing system” — the complex network of underground drainage pathways that are a part of the water cycle. Human-caused sinkholes can force a similar reaction through artificially creating what scientists call “void space” in the ground. This affects how much water the soil can hold and can cause it to collapse.
“If you come in there and dig something or put in something or build something or modify the water flow … you’re likely to have nature react to that,” Kastning said. In particular, pumping water out of aquifers and pouring concrete or asphalt, for foundations or roads, for example, causes depressions and allows sinkholes to form.
While these depressions can be caused by a variety of factors, the main culprit is rain. Warm temperatures can also make the ground and the rock within it softer. Sinkholes after a storm like Helene, Kastning said, are part of nature’s way of righting itself. But if big storms happen more often, so will sinkholes. “The frequency of these things is increasing,” he said.
But so too are the unique opportunities they present.
On a sunny April afternoon, three scientists walked across an ancient sinkhole, long since filled in and covered in grass, on the Gray Fossil Site in Gray, Tennessee. Active archaeological digs are currently covered with black plastic and protected by fences.
The 4.5-acre, 144-foot deep pit and surrounding forest once provided water to prehistoric animals and, when they died, served as their grave. As museum collections manager Matthew Inabinett put it, “When a place is a good place to live, it’s also a good place to die!”
Gray Fossil allows scientists to peer 4.5 million years into the past. Of course, they’ve only (literally) scraped the surface. “We’ve estimated a few tens of thousands of years at current rates to excavate to the bottom,” said fossil site Americorps member Shay Maden. “So we’ve got job security on that front for sure.”
They’ve found fossils of exciting species like giant flying squirrels and mastodons, but also have seen more familiar faces, including rhinos (one of which the team named Papaw, since he died at an advanced age) and tropical reptiles. The site, Inabinett said, has become a scrying glass to understand climate conditions of the past. It can also suggest what things might look like in a world a few degrees warmer than today.
Many of the fossils found so far are from the Pliocene epoch, which ended about 2.6 million years ago and was about 3 degrees Celsius warmer than now. That’s also about how much warmer Earth is projected to grow by 2100. Oceans were about 25 feet higher back then, and alligators lived in Appalachia. The region’s biodiversity, once among the greatest in the world, survived multiple periods of extreme heat and cold. Later, the humid climate of the Pliocene quickly succumbed to the Ice Age.
Because silt flows toward the ocean, the Appalachian region has few easily accessible fossils, making Gray Fossil a primary window into the ancient past. “The Southern Appalachians are one of the most biodiverse regions in North America,” Inabinett said. The early Pliocene time period is a crucial era for understanding the origins of diversity in our planet’s history. Researchers and scientists have found that studying this time period provides valuable insights into how different species evolved and adapted to their environments.
One fascinating aspect of studying the early Pliocene is the discovery of sinkholes. While not every sinkhole opens a portal to the prehistoric past, each one taps into something primal and mysterious. For individuals like Bacchus, who regularly explore sinkholes to understand their formation and growth, these natural phenomena represent more than just geological features – they symbolize the vast unknown that lies beneath the surface of the Earth.
Bacchus explains, “I am attracted to sinkholes because of the humbling feeling they evoke. They remind me that I am just a small part of this planet, and there is so much more happening beneath our feet than we can imagine.” Sinkholes serve as a reminder of the complexity and interconnectedness of the natural world, prompting people to reflect on the bigger picture and their place within it.
By delving into the early Pliocene era and examining the geological formations like sinkholes, researchers gain a deeper understanding of the Earth’s history and the processes that have shaped the planet over millions of years. These studies help us trace the origins of biodiversity and uncover the evolutionary pathways that have led to the incredible diversity of life we see today.
In conclusion, the early Pliocene period offers a wealth of knowledge and insights into the origins of diversity on Earth. Studying this era, along with natural phenomena like sinkholes, allows us to unravel the mysteries of our planet’s past and gain a greater appreciation for the intricate web of life that surrounds us.
