CHAMPAIGN, Ill. – I’m standing in the shadow of a woolly mammoth outside the Natural History Building on the north end of the Quad, listening to two of my colleagues talk about mammoths and mastodons. Our tour of the geology of the buildings and monuments that edge the Quad has not yet begun, but my education has. The mammoth is a life-sized resin sculpture of a beast that once roamed this part of the world.
News Bureau physical sciences editor Lois Yoksoulian, our tour guide today, tells arts and humanities editor Jodi Heckel that the primary distinctions between mammoths and mastodons involves their tusks and teeth. Like elephants, mammoths had ridged teeth that could pulverize grasses and other soft plants. Mastodons had rounded “breastlike” teeth (their name derives from the Greek for “breast” and “tooth”) that allowed them to grind up twigs and other woody vegetation. Mammoth tusks also curved more dramatically, sometimes even crossing in front of them.
“I love mammoths,” Heckel says, by way of conclusion.
This is the first lesson for me on a special tour of the ancient history of the Quad. A crowd of curious colleagues, 20 people from the campus office of Strategic Communications and Marketing, has assembled here in the bright summer sun to learn about the geology we tend to overlook. This is part of a StratCom effort to learn more about the campus we represent.
Yoksoulian makes a perfect guide. She got her academic start in geology, earning a Ph.D. in earth and environmental sciences from the University of Kentucky and working for five years as a postdoctoral researcher at the Illinois State Geological Survey. In the process, she discovered a passion for science communication. She went back for a master’s in journalism at the U. of I. and joined the News Bureau team in 2017.
While the resin mammoth isn’t a geological feature, it does fit with the theme of the tour. The beast stands among plants that were likely familiar to it in its day: grasses, sedges and junipers, among others. The designers of this landscape, including earth science and environmental change professor emeritus Stephen Marshak, call it a Pleistocene garden, with plants that would have grown here tens of thousands of years ago, Yoksoulian says.
There also are boulders — glacial erratics, she says, dragged from lord-knows-where when the glaciers advanced across the landscape and dumped here when the last of them retreated roughly 13,000 years ago. The same large-scale climate shifts that erased the glaciers from this landscape also doomed the mammoths. These boulders are metamorphic rocks, classified as gneiss and schist.
It’s hot outside, and for a moment we step inside the NHB’s cool back stairway to ponder its lovely stone cladding. This is stylolitic limestone, Yoksoulian says.
“Stylolites are serrated, interlocking seams or zigzag lines commonly found in carbonate rocks like limestone, which are believed to be an intermediate between limestone and marble,” she says.
These rocks were subjected to just enough heat and pressure to dissolve some of the minerals away, “leaving behind jagged surfaces and concentrated insoluble materials like clay or organic matter,” she says. The color of the seams varies depending on the minerals involved. Iron-rich seams are red, for example.
Our next rock stop is Harker Hall. Our guide directs us to look up at the slate roof, and we all learn something I’ll bet none of us knew before: slate comes in colors beyond just the standard bluish gray. The roof tiles are laid in a geometric pattern of blue, teal and red. These are the stones’ natural colors. They have not been treated or dyed.
“The 500-million-year-old red is rare,” Yoksoulian says.
Over the course of the tour, we stop at Noyes Hall to look at its granite stairs (the group murmurs when Yoksoulian mentions their age: 1.8 billion years), we ponder the Indiana limestone on the exteriors of several buildings, including Foellinger Auditorium (limestone is too easily weathered to be used on flat horizontal surfaces outside, Yoksoulian says), and we marvel over the gorgeous “Alabama white” marble lobby of Lincoln Hall. This marble is a metamorphosed limestone, brought here from Talladega County, Alabama.
“I’ve probably noticed more rocks in the last 10 minutes than in all my time on campus,” says StratCom’s director of executive communications and issues management Pat Wade as we walk from building to building.
“It feels wrong to step on them,” says videographer Andy Savage after pondering the ancient granite stairs outside Foellinger Auditorium.
We also peer closely at the fossil-rich limestone on the walls of the Henry Administration building’s south entrance, a place Yoksoulian says she often visited for inspiration during her pre-COVID-19 days, when she still had an office on campus. Group members peer at the rock for evidence of the tiny invertebrate creatures that were trapped in the sediment some 460 million years ago. These include brachiopods, bryozoans, corals, crinoids and others.
Another highlight of the tour is the terracotta brickwork on the façade of Davenport Hall.
“Both bricks and terracotta are made from mixtures of sand, clay or lime, plus water; the material is kneaded together, shaped or molded, then fired in a kiln to dry and harden it,” Yoksoulian says. Some of the clay is a nonswelling type called illite because it was first found in Illinois. Not swelling is a good attribute for a building material, she says.
The bricks and columns are a lovely tawny orange color. The façade fits in with the rest of the brick-rich Quad but also ornaments it in a unique way. Yoksoulian points out that the columns were made in ringed segments, each more than a foot tall, that were stacked together with mortar to form a perfect, tapering column.
Ralph Grim, a research professor of geology who taught at Illinois from 1948 to 1967 and was the first to discover and describe illite, is considered the “father of clay mineralogy,” a very challenging discipline, Yoksoulian says. Her academic “family tree” extends back to Grim, she says. (His protégé trained her Ph.D. supervisor.)
Having completed almost a full circle around the Quad, we end the tour with Altgeld Hall and the statue of Alma Mater “and her friends,” Yoksoulian says. Altgeld’s surface is clad in Hinkley Sandstone, which was “quarried in the appropriately named town of Sandstone, Minnesota,” she says. The rock is 500-600 million years old.
The porous sandstone has attributes that make it good for filtering and cleaning groundwater, but when exposed to the atmosphere it also soaks up airborne pollutants, gradually darkening over the years. An exterior cleaning of Altgeld that was completed in 2025 restored much of its original pale orange color.
Finally, we learn about Alma’s pink granite pavers and dark granite base. These pavers came from Stony Creek Quarry in Connecticut, Yoksoulian says. The same material was used on the Brooklyn Bridge, New York’s Grand Central Station and the base of the Statue of Liberty.
Alma’s enduring platform seems a fitting tribute to the university, which, like the rock out of which it was built, has weathered many seasons while supporting the mission of “learning and labor.”
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