Over two million years ago, Lake Agassiz was a vast glacial lake that sprawled across North Dakota and into Canada. It was larger than the area of all the Great Lakes combined. The lake was named after Louis Agassiz, a geologist who conducted extensive studies on the movement of glaciers. Today, Agassiz lives on in the names of North Dakota schools, libraries, businesses, and nonprofits.
What is less well known is that about 60 million years ago, western North Dakota was densely forested. Today it is hard to imagine a subtropical forest with trees up to 12 feet in diameter and over 100 feet tall. In fact, on this date in 1910, geology professor D.E. Willard punctured what he considered were tall tales of massive trees. He assured the readership of the Devils Lake Inter-Ocean that there were no petrified trees in North Dakota. Willard said he examined cylindrical masses that resembled petrified trunks of trees that were found along the Cannon Ball River. He said these formations were merely sediment from the long-gone Lake Agassiz. He completely discounted the theory that a vast Dakota forest had left behind evidence in the form of petrified tree trunks.
But it turns out that North Dakota is indeed home to one of the largest petrified forests in the United States. The Petrified Forest Loop is a 10-mile trail in Theodore Roosevelt National Park, classified as a moderate to strenuous hike. At first glance, a visitor might think the landscape is strewn with boulders. A closer look at the rocky ground reveals that the boulders are not boulders at all. They are the petrified remains of a forest.
Most of the remains are stumps that were covered with sediment and mineralized over millions of years. Over time, erosion revealed the petrified wood. These massive stumps and smaller rock-like pieces are the remnants of a vast forest. The trail is located in the remote northwest corner of the South Unit. In addition to the petrified trees, a hiker might also spot bison and wild horses.
Dakota Datebook by Carole Butcher
Sources:
Devils Lake Inter-Ocean. “No Petrified Trees in Dakota.” Devils Lake ND. 3/25/1910. Page 9.
ScienceDirect. “Glacial Lake Agassiz.” https://www.sciencedirect.com/topics/earth-and-planetary-sciences/glacial-lake-agassiz Accessed 2/21/22.
National Park Service. “Theodore Roosevelt National Park.” https://www.nps.gov/thro/planyourvisit/hiking-and-trail-information.htmAccessed 2/21/22.
Only in Your State. “Hike to This Ancient Forest.” https://www.onlyinyourstate.com/north-dakota/ancient-forest-hike-nd/ Accessed 2/21/22.
