Forty plus folks file out of an iconic yellow school bus, a steel body made ambulant through the combustion of fossilized plants and animals (oil and gas) that lived and died between 10 and 180 million years ago. We step onto ground that was located just south of the equator 300 million years ago, during the geologic epoch referred to as the Carboniferous. Presently, this ground is a preserved forest ecosystem, called Ferne Clyffe State Park, at the southern tip of the state of Illinois. Our guides, Scott Elrick and Jeremy Breeden, two geologists with the Illinois State Geological Survey, unfold a massive paleogeographic map, spanning 500 million years, and attach it to the side of the bus with magnets. As we gather around, clutching the circulating handouts and wrapping up in scarves, the early fall winds rustle the leaves in the trees.

This is the second of several events to unfold over the weekend of October 11–13, 2019, as part of Field Station 4: Confluence Ecologies in the Confluence region of the Mississippi River. Field Station 4 is one of six Field Stations presented by different groups of artists, activists, and scholars along the Mississippi River Basin, developed for the ambitious multisite project Mississippi: An Anthropocene River, envisioned by Haus der Kulturen der Welt  of Berlin. The five members of Deep Time Chicago who organized this particular walk—Amber Ginsburg, Claire Pentecost, Kayla Anderson, Sara Black, and Sarah Lewison—did so with the intention of creating a provocative and exploratory juxtaposition to their sound and sculptural installation Inheritance (2019), presented to the public for the first time the night prior at the University Museum at Southern Illinois, as part of the Confluence Ecologies exhibition. The fossil forest system that is the subject of Inheritance straddled an ancient river basin near Galatia, Illinois, at its center a river that meandered across these lands 300 million years ago. The swampy peat soils from which the now fossilized forest once grew became the coal seams that have fueled the coal industry of Southern Illinois and neighboring states for generations. The fossil forest, a rare picture of a complex ecosystem, was rather rapidly covered over by fluvial sediments during a warming period that was not fully dissimilar to the one we are experiencing now—albeit this one is fueled by anthropogenic intervention.

We stay for a time huddled around the massive map poster, getting a grand timescale glimpse of the landscape, and then move on to the trail, making intermittent stops under and amid rocks that demonstrate events of the latter part of the Carboniferous period, the Pennsylvanian. Elrick offers the group a lesson about climate cycles to help us imagine the humid climate conditions that cloaked this fossil forest those 300 million years ago. Using his rare capacity for making incomprehensible timescales somehow comprehensible, he goes on to tell a story of one of Earth’s heartbeats—what, in climate science terminology, is referred to as glacial-interglacial cycles. Elrick explains that the temperature and atmospheric CO2 traces of glacial-interglacial cycles over time appear much like an electrocardiogram, with regular and predictable spikes and falls. That is, until, the geologic recent. On the far right side of this undulating line, we see a sharp, almost vertical curve, first documented by Charles Keeling starting in 1958 and continuously monitored since. This rapid upturn is called the Keeling curve, extending upward from 1958 as the carbon concentration in the atmosphere soars past the Earth’s average high point—250ppm—and further onward to 409 ppm as of November 2019. This spike is a result of the anthropogenic combustion of extracted ancient fossil forest systems (coal), natural gas, and petroleum. Finally, Elrick offers us the seeming paradox that, though global warming does lead to more liquid water on Earth, as ice caps melt and as sea levels rise—sometimes very rapidly—it can also lead to less water for some portions of the Earth. For example, climate systems at low latitudes can dry up, causing lush plant growth to diminish and the land to become less capable of holding water and sediment, and thus more susceptible to erosion. This story is locked into the very rocks surrounding us.

Inside of Hawk’s Cave, we gather in a vast negative space cut by erosion over millions of years. We are dwarfed under sedimentary layers that make an impressive cantilevered ceiling above us. Breeden demonstrates by voice and gesture that these layers are not a simple story of accumulation, one layer on top of another, static for infinitude. Rather, the layers were deposited, covered for millions of years, and over time eventually exposed, eroding into the shapes seen today. With his training as a deep-time thinker, he reads to us this geological story. Before departing Hawk’s Cave, our guides shift our attention toward a tube-shaped opening at the top of a sandstone boulder, perhaps five inches in diameter and sixteen inches long. In that spot, a tree branch was buried in sandy sediment that, over time, hardened to sandstone rock. The branch itself dematerialized, rotting away, to leave this tubular space. A trace of life that was. So, too, the Illinois Basin, a huge bowl-shaped depression filled with millions of years of intercalated layers of lithified sand, silt, clay, limestone … but also layers of compressed plant material—former peat soil that was covered, preserved, pressed, and heated, not decaying into open spaces but transforming into coal. Carbon. Accessible for human extraction.

The coal layers are accumulations of generations of plant species that flourished in the high-oxygen atmospheres of the Carboniferous. The high oxygen levels enabled life forms to grow to comic-book size. Millipedes five feet long, dragonflies with two-foot wingspans, and cephalopods, squid-like creatures, the length of a baby whale. At the end of each glacial episode during the Carboniferous period, when climates changed from wetter to drier at the equator and soils became more prone to erosion from declining vegetation, a series of flood events prompted by rising sea levels encapsulated and preserved the swampy forest along the ancient river channel near Galatia, Illinois. The flooding river brought sediment out of the river channel and deposited it into the adjacent swamps, covering the standing vegetation and creating the anaerobic conditions that allowed certain sections of the standing forest, including the peat soils now coal, to be captured in time and preserved. The last generation of this flourishing swamp ecosystem was preserved as a moment in time. Only a handful of geologists and coal miners have physically touched the fossil specimens at the site of preservation, but entire generations of us have consumed this site’s energy through the combustion of its molecular carbon. As we gaze at this contemporary forest growing from the ancient strata, standing adjacent to the Mississippi River channel and living during the sixth mass extinction, I wonder: Are we witness to this ecosystem’s final flourishing?