Watford City in McKenzie County, North Dakota — The American Midwest (Upper Plains)

“Cannon Ball” Concretions

Photographed by Bill Coughlin, July 21, 2015

1. “Cannon Ball” Concretions Marker

Inscription.
The large spherical boulders in front of you are called concretions. They may have any shape, but most are round. Concretions are formed within rocks (shale, clay, sandstone, etc.) by the deposition of mineral around a core. More concretions will be exposed here as erosion continues.

Erected by National Park Service, U.S. Department of the Interior.

Topics. This historical marker is listed in this topic list: Natural Features.

Location. Marker has been reported permanently removed. It was located near 47° 35.783′ N, 103° 19.933′ W. Marker was in Watford City, North Dakota, in McKenzie County. It was on Scenic Drive, on the right when traveling north. Marker is located at the Slump Block Pullout in the North Unit of Theodore Roosevelt National Park. Touch for map. Marker was in this post office area: Watford City ND 58854, United States of America.

We have been informed that this marker is no longer there and will not be replaced. This page is an archival view of what was.

Regionally, this marker was in North Dakota’s Bakken Oil Patch.

It was also in the American Lewis & Clark Corridor,

on the prairies,

and on the Northern Plains.

Globally, it was in North America,

the Western Hemisphere,

the Western World,

and the Anglosphere.

Historically, it found itself in what was once Rupert’s Land

and also the Louisiana Purchase.

Other nearby markers. At least 8 other markers are within 4 miles of this location, measured as the crow flies: Cannonball Mystery (a few steps from this marker); North Dakota Badlands (approx. one mile away); The Long X Trail: A Dusty Trail to Greener Pastures

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(approx. 1.4 miles away); Tilted (approx. 1.4 miles away); Layers in Time / Portraits in Stone (approx. 1.9 miles away); The View that Launched a Park (approx. 2.3 miles away); Bentonitic Clay (approx. 2.9 miles away); Theodore Roosevelt National Park (approx. 3.4 miles away). Touch for a list and map of all markers in Watford City.

Other markers no longer nearby. Long X Cattle Trail (was approx. 0.8 miles away but has been permanently removed); Slump Formation (was approx. 1.4 miles away but has been permanently removed); Longhorns (was approx. 2 miles away but has been permanently removed); Building From Hard Times (was approx. 2.3 miles away but has been replaced with another marker now near it).

Photographed by Bill Coughlin, July 21, 2015

2. “Cannon Ball” Concretions Marker

Marker in Theodore Roosevelt National Park image. Click for full size.

Photographed by Bill Coughlin, July 21, 2015

3. Marker in Theodore Roosevelt National Park

“Cannon Ball” Concretions image. Click for full size.

Photographed by Bill Coughlin, July 21, 2015

4. “Cannon Ball” Concretions

Credits. This page was last revised on October 13, 2025. It was originally submitted on September 14, 2015, by Bill Coughlin of Woodland Park, New Jersey. This page has been viewed 793 times since then and 31 times this year. Last updated on August 19, 2025, by Susan Van Den Bosch of Almond, Wisconsin. Photos: 1, 2, 3, 4. submitted on September 14, 2015, by Bill Coughlin of Woodland Park, New Jersey. • Devry Becker Jones was the editor who published this page.