Explore the Cannonball Concretions
What to Expect
Safety Advisory
Bentonite clay becomes extraordinarily slippery when wet. A light drizzle can turn the gentle slope into a slide. If the ground looks dark and shiny, watch every step or wait it out.
There is zero shade at this stop. In summer, the exposed clay and rock radiate heat back at you. Even for a fifteen-minute visit, sun protection matters — the North Dakota sun at this latitude is no joke from June through August.
Trail Details
Pro Tips
Hit this stop on your way into the North Unit, not on the way out — afternoon light rakes across the concretions and deepens the shadows in the eroded clay, making the formations look even more dramatic than they do under flat midday sun.
Wear shoes with decent tread even for the short walk. The bentonite clay around the concretions turns into a slick, boot-sucking mess after any rain, and the hillside is steeper than it looks from the pullout.
Walk past the obvious first cluster of concretions. Most visitors photograph the roadside specimens and leave, but the larger and more photogenic formations — including several balanced on narrow pedestals — sit further up the slope where almost nobody ventures.
Photos
NPS Photo/J. Zylland
