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Palmisano Park, Chicago. Original quarry high wall in background.

I recently participated in a workshop on America’s Geoheritage. What is geoheritage? One definition is that this an area with geologic features with “significant scientific, educational, cultural, and/or aesthetic value.[i]” One form of geoheritage sites is: “places where geologic features or landscapes played a role in cultural or historical events”. Although there is an unofficial list of geoheritage sites maintained by the National Park Service[ii], the naming of such sites is still in its infancy (thus the workshop). Many locations in Chicago and the surrounding region are prime candidates for eventual designation as culturally and historically significant geoheritage sites. …


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My Great grandmothers brass candlesticks

At the beginning of the Jewish New Year last week I lit candles to mark the day. The candlesticks I used were my maternal great grandmothers, brought with her to America in 1910. These were passed to my grandmother, then to my mother, and finally to me and my family. Staring at the candles connected me to an ancestor I had never met; I only know of her from a single photograph and the stories my grandmother and mother told. Of my other great grandparents, I know even less, just names and photos. But I am connected to them also. …


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Earth’s climate has gradually cooled for the last 50 million years, culminating in Northern Hemisphere ice ages where ice sheets periodically advance and retreat. The ice last began to rapidly retreat about 18,000 years ago. Based on current greenhouse gas emissions, global temperatures over the next century and beyond will reach levels not reached for millions of years. CREDIT Thomas Westerhold. Ref: Westerhold, T., et al. 2020. An astronomically dated record of Earth’s climate and its predictability over the last 66 million years. Science 369(6509):1383–1387.

It’ll start getting cooler. You just watch,” — President Trump

“I wish science agreed with you,” — California official.

“I don’t think science knows, actually,”- President Trump.

It’s nice to know that President Trump understands Milankovitch cycles. In 1976 it was conclusively demonstrated that the multiple advances and retreats of the Northern Hemisphere ice sheets over the last 2.5 million years are controlled by small periodic changes in the Earth’s orbit[i], a hypothesis put forth decades earlier by Milutin Milanković. Over roughly the last one million years, the ice has grown and retreated on a cycle of about 100,000 years, with the growth of the ice being gradual and the decline relatively sudden, producing a distinctive “saw-tooth[ii]” The last deglaciation occurred between 20,000 and 10,000 years ago, with global warmth peaking about 6,000 years before present. So, indeed, the world should “start getting cooler” and in fact already has a bit. But this is a very slow cooling and will not be noticeable for millennia. That is, if natural processes are allowed to run their course. …


In 1986, Paul Simon sang of the “Boy in the Bubble.” The real boy in the bubble, David Vetter, suffered from severe combined immunodeficiency (SCID) and lacked immunity to infection. He lived in sterile enclosures until he died in 1984 at the age of twelve, following an unsuccessful attempt to cure him.

We all live in different bubbles, designed to keep harm out. Some of these, like family, we are consciously aware of. Others are hidden from us until outside incidents or individuals make us aware of them. In some cases, we may even reject the idea that they exist. The walls of the bubbles can block our view of what is outside them. …


“Is there anybody out there?” — Pink Floyd

Sometimes technology takes a long time to develop. One of my childhood memories is seeing the AT&T Picturephone at the 1964 World’s Fair in New York. The technology was also featured in the 1968 film 2001, where a video call was made from a space station. This early promise was never delivered on; almost no one in the late twentieth century had a Picturephone. Now a half-a-century later, being able to see who we are talking to has become a given. Whether it is Zoom, Skype, Facetime, or Google Hangouts, and no matter which of our myriad devices it is on, the ability to synchronously transmit voice and video is now easy for much of humanity. …


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Spectators at the Gondwana vs. Laurentia soccer game at the 2012 quadrennial international ICHNIA meeting in Newfoundland. Such events help build relationships among researchers from diverse backgrounds.

As most of us shelter in place, many voices have suggested that this is an excellent to time to reflect on and perhaps reform some basic aspects of society, such as the pay of “essential workers” or universal health care. The scientific enterprise is no exception; in particular, the pandemic has hastened an already ongoing movement to rethink a cornerstone of the enterprise, the scientific conference. As I wrote last time, the recent International Association for Landscape Ecology — North America chapter meeting I attended was transformed in an astonishing five weeks from a traditional in-person meeting to fully online. But the movement in this direction had already started; Janet Silbernagel, then President of IALENA wrote to membership in April: “ In becoming IALE-North America last year, we had an immediate goal to encourage more participation from Mexico and other parts of North America, while also recognizing that meetings outside of the US might pose travel barriers for US government employees. So, we were planning to pilot some virtual conference options at Toronto that could become models for future meetings. …


I have been attending scientific conferences of various kinds over my entire career. Some things have changed over the decades; most notably (and thankfully) PowerPoint has replaced 35 mm slides. But the overall structure has not changed. There are short talks, generally fifteen minutes long, presented consecutively from a podium and illustrated by slides. Often there are competing sessions organized around specific themes. There are sometimes plenary talks, where a distinguished member of the profession speaks at length on a topic of general interest. Accompanying the oral presentations are poster sessions, where anxious presenters, often students, will stand in front of their posters and try to attract the interest of meeting participants strolling past. …


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A forest fire model generated using NetLogo https://ccl.northwestern.edu/netlogo/

A number of years ago, my explorations into fractals led me to the amazing concepts of percolation theory and how they could be used as a heuristic tool to explore a whole range of phenomena. The basic concept of percolation theory is easy to explain, using the “forest fire” model. Imagine a square grid, some 100 cells on each side. Now randomly plant a tree somewhere in the grid. Plant another and another until about 10% of the grid cells have a tree on them. Next, send down a lighting bolt down onto the grid. If it hits a tree, the tree catches fire. The burning tree can ignite any tree in an adjoining cell (north, south, east, or west) and those trees can in turn ignite their neighbors. When only 10% of the cells are planted, most trees are isolated or are in small groups. Any fire quickly dies out. Let’s plant more trees. At 20% of the cells occupied, the fires are bigger but still isolated. The same is true at 30%, 40%, and 50%. The trees are in bigger, but still isolated groups. Fires, still started by a single lightning bolt, only burn a part of the grid. It is when the percentage of occupied cells starts to reach 60% that something remarkable happens. At about 59.28% of cells occupied by trees, there is about a 50% chance that the fire will spread from one side of the grid to other; it “percolates.” If one looks at the size of the largest connected cluster of trees on the maps, it jumps non-linearly upward at that value. Although we have not changed the local rule: “if you catch fire you burn your immediate neighbor,” the behavior of the entire system has changed. What was a small local fire becomes a system-wide conflagration beyond this critical value. …


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A caddisfly case from the Oligocene of Montana. The case is made of tiny ostracode shells.

In a Peanuts comic that had a place of honor on my dorm door, Peppermint Patty is taking an exam and is asked to: “Explain World War II.” Patty incredulously responds: “Explain World War II !?” The last panel, further explains: “Use both sides of the paper, if necessary.” I recently had a similar reaction, when science reporters, interviewing me about my most recent paper, asked me to explain in a few words, “when do bones and teeth become fossils?” Although they are orders of magnitude fewer in number than those written about World War II, nevertheless there are many books and many hundreds of academic papers written about the formation of fossils, the science of taphonomy. Not so simple to answer in a couple of sentences. …


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In some Chicago neighborhoods, you can still see where the sidewalks were raised.

About 20,000 years ago, where I am sitting in Chicago was covered by about a kilometer of ice. This was the height of the most recent advance of ice sheets in the Northern Hemisphere, which had begun some 80,000 years earlier. About 15,000 years ago the ice sheets began to retreat and within the next 5000 years they had totally disappeared. These great ice sheets left an indelible mark on the landscape, the most notable being Lake Michigan and the other Great Lakes, carved by the glaciers in the underlying bedrock. Paralleling the current shore of Lake Michigan to the south and west are linear hills, moraines, up to a hundred feet high, deposited by the glacier as it temporarily slowed in its retreat. And as the ice melted it produced an ancestor to Lake Michigan, Lake Chicago, whose northeastern shore was the retreating glacier and whose southwestern shores were the morainal hills. …

About

Roy Plotnick

Paleontologist, geologist, ecologist, educator. Professor at the University of Illinois at Chicago. Website:https://sites.google.com/uic.edu/plotnick/

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