Exploring the Geologic Wonders of North-Central Montana
Into the bull’s eye.
As a teacher in north-central Montana, I find immense joy in exploring the unique geological landscape that surrounds me. My fascination lies in understanding why the land looks the way it does, and I use tools like Google Earth to get a bird’s eye view of the area’s landforms. A few years ago, while perusing Google Earth, I stumbled upon a curious circular feature on BLM land, about 10 miles south of Hays. The satellite view revealed an intriguing series of concentric circles—almost like a giant target spanning a few miles across. What’s fascinating is that this target-shaped landform is invisible from the ground; it can only be appreciated from above. A little research provided some insights into its formation, but it wasn’t until recently that I ventured down there to explore it more closely.
Got domes?
The mysterious feature is an “igneous dome,” formed when lava pushed up through sedimentary layers tens of millions of years ago. Instead of reaching the surface, the lava solidified beneath these layers, creating a dome-like formation. Over millions of years, this dome has eroded, leaving behind concentric circular ridges of rock. There are several such domes in the area, each unique, formed by ancient plumes of lava that pushed layers of rock upwards. The Little Rocky Mountains, located to the north of these isolated domes, were formed by lava intrusion around 50-55 million years ago. For more about that, see my article titled “Wall Walk in the Little Rockies.”
First Shot.
On August 25th, my friend Rick and I embarked on our first hiking adventure into the dome. Unfortunately, we didn’t have a great trail plan, and we didn’t carry enough water, so we didn’t get to explore much of the dome. I underestimated how challenging it would be to navigate up and down those concentric ridges. Our walk back took us below the striking sandstone cliffs on the southern edge of the dome. We took a well-deserved break there while I captured some drone photos and pondered a better route for my next visit.
Take 2.
Rick wasn’t available for a second trip on September 15th, but I was better prepared—having mapped out a more reasonable route, eaten a hearty breakfast, got an earlier start, and packed plenty of water. This time, I walked along Bull Creek for much of the way, deviating to complete a clockwise loop near the northern end of BLM land and again to explore the cliffs on the southern end before leaving the dome. Bull Creek meanders north to south right through the center of the dome. Hiking along the dry creek bed was straightforward but felt like I was missing out on views. There was some mud and a few cows along the way. On the way back, I hurried up a ridge to a beautiful grassy bench and then walked over to explore the sandstone cliffs—without a doubt, the best part of my day. The hike, which ended up being 12.3 miles, took 8 hours, mostly because I spent so much time exploring those stunning cliffs.
FYI—I’ve recently started an Instagram account. I plan to share something interesting at least once a week. Check it out: rodbenson406
Interactive Map: Featured Hikes in North-Central Montana
Below is an interactive map marking the hikes that have been featured on bigskywalker.com so far, including several in Glacier Park. Click full screen to expand, focus for more details, or click on a marker for a link to the post: