Ancient Wood: Finding Natural History in Carver, MN

Ancient specimens can shed light on Minnesota's landscape of eras past

Published04/29/2021 , by Emily Dzieweczynski

Two people in bright yellow construction gear standing in a 18ft deep hole

Sometimes curiosity, wonder, and a keen eye are all it takes to make fascinating discoveries. That’s what happened on an old plot of farm land in Carver, Minnesota. With a bit of knowledge about the history of the landscape and a lot of curiosity, a couple of brothers encountered a unique find. It turns out that this discovery—a 14,000 year old piece of wood—has a lot to teach us about Minnesota’s landscape in eras past.

The story began at a construction site in Carver, Minnesota, where Joel Kassen was digging utility lines. Then, 18ft below the surface of the Earth, he noticed something strange—a lone piece of wood. Joel and his brother Gary Kassen did a double-take—it certainly seemed unusual for a piece of wood to be buried that far beneath the surface! Almost immediately it occurred to them this wasn’t an ordinary piece of wood and very likely had a story to tell about Minnesota’s landscape.

In fact, as the brothers would soon learn, this was the first time that the piece of water-logged wood saw the light of day in thousands of years. Gary Kassen shared that his two hobbies are woodworking and history, so he took an immediate interest in the finding. By having previous knowledge and experience working with wood, Kassen could tell by the grain of the wood that this wasn’t a familiar tree. This caused his fascination to grow even more, as this unfamiliar wood was found on familiar land—the plot of land where it was discovered lies just next to the one that his family farmed on for over 100 years.

Kassen contacted the University of Minnesota and was put in touch with the Bell Museum’s Herbarium Collection Manager Timothy Whitfeld. Sharing in Kassen’s curiosity, Whitfeld set out to have the wood radiocarbon dated. Soon, the lone piece of wood found beneath the Earth in Carver was on its way to the Lawrence Livermore National Laboratory in California.

In February, the results came back. While they are still unsure of what kind of tree the wood came from—a spruce is Whitfeld’s guess—it was determined that the wood is between 14,033-14,433 years old. This confirmed Kassen and Whitfeld’s suspicions that the wood is of Pleistocene origin. Around 10,000-12,000 years ago, Carver was covered by glaciers—specifically, the Des Moines Lobe ice advance—and this glacier is the reason why the wood was buried so far beneath the surface. When glaciers move over a landscape, they pick up everything from trees to pebbles, rocks, and boulders. When they melt, however, they leave behind everything they’ve picked up on their way. That’s how this piece of wood came to rest 18ft below the surface of the Earth, explained Whitfeld.

A piece of ancient wood

What is carbon dating?

Radiocarbon dating is a method of determining the age of an object that contains organic material—which includes any organism that is living or once lived. It uses the properties of radiocarbon—a carbon isotope—which is a form of carbon that differs from other forms in its relative atomic mass.

Radiocarbon is created in the atmosphere through the interaction of cosmic rays with atmospheric nitrogen. It combines with atmospheric oxygen to form carbon dioxide. This is incorporated into plants through photosynthesis and animals acquire radiocarbon by eating plants. When the animal or plant dies, it stops taking up carbon from its environment, and the amount of radiocarbon it contained before dying begins to decrease as the radiocarbon decays. The amount of radiocarbon measured from a dead plant or animal provides information that can be used to calculate when the animal or plant died. For example, older samples contain less radiocarbon.

Kassen decided to donate a portion of the wood to the Bell and the rest will go to a museum in Carver—Kassen hopes for the Carver County Historical Society and Museum. He explained that this museum feels important because of its locality to the place where the wood was discovered and that this could be a valuable learning tool for school groups in the area. It might be hard to imagine the glaciers that once rested on Minnesota’s landscape, but natural history can become much more tangible when there’s something to look at.

“A lot of people are visual learners and seeing something physical makes things more real. This wood could be an education tool because having something physical can help students relate to the glacier period,” shared Kassen.

A child looking with amazement at a piece of wood In regards to the wood’s place in the Bell’s collection, Whitfeld hopes that it can be on display somewhere in the MN Biodiversity exhibit or that it could stay in the herbarium to be used for programs or temporary exhibits.

From Whitfeld’s perspective, this wood is a unique specimen and is not like the other specimens that the Bell has in the herbarium collection. Typically, herbarium specimens are collected while they are still living, to document that a particular species was growing at a certain location at a certain time. The ancient wood specimen, however, tells us something about the things that were living—it tells a story about a specific place in the past. By uncovering this ancient wood, we time-traveled back to a period where glaciers covered the sprawling Minnesota landscape and learned more about the events that took place thousands of years ago.