White Butte – North Dakota’s Highest Point – 3,506 feet
Though not part of the Maah Daah Hey Trail System, White Butte is located southeast of Amidon, ND about 8.7 miles or 30 miles southeast of Burning Coal Vein Trailhead the southern terminus of the Maah Daah Hey Trail. If you are a highpointer or you are just curious about what you can see on a clear day take advantage of the improved access road, trailhead parking, and the 0.9 mile trail to the top.
White Butte Geology
White Butte displays three distinct period of deposition resulting in the Arikaree, Brule and Chadron Formations. It is unknown how many other strata were deposited above the Arikaree Formation as these were eroded away leaving the harder Arikaree sandstone.
Miocene Arikaree Formation is the caprock protecting the softer strata from erosion and was deposited between 5.3 and 23 million years ago. This stratum consists of concretionary cross bedded limestones and gray/green to white sandsotnes, conglomerates, siltstones and claystones. The rocks contain mammal bone fragments and the conglomorates contain pieces of clinker (“scoria”) indicating lignite has been burning for millions of years.
Brule Formation is only 25 feet thick on White Butte and is comprised of white colored siltstones. A significant portion was eroded prior to the deposition of the overlying Arikaree Formation.
South Heart Member of the Chadron Formation consists of brown to gray green semtetic claystone that contains thin lens-shaped beds of freshwater limestone. Smetetic clay is mined in the USA for commercial and industrial uses and is more commonly known as bentonite. South Heart claystones have “popcorn weathering” surfaces and drape over the underlying stratum making it difficult to determine where one strtum ends and the next stratum begins. The member is about 95 feet thick at White Butte. The Chadron Formation was deposited between 32 and 34 million years ago.
Chalky Buttes Member of the Chadron Formation consists of white, gravel bearing cross-bedded sandstones and sandy mudstones. The cliffs of the Chalky Buttes member erode to a more vertical cliff than the overlaying South Heart Member. The thickness of this member at White Butte is about 100 feet.