White Butte is the highest natural point in the U.S. state of North Dakota. At an elevation of 3,506 ft, it is a prominent butte in Slope County, in the Badlands of the southwestern part of the state. It is located 3 miles east of US 85 and about 6.5 miles south of Amidon. The summit is located within the boundaries of the Little Missouri National Grassland and is about 35 miles south of Theodore Roosevelt National Park. It is on private property, owned by the Dennis family who live nearby.
The story of the badlands begins over 65 million years ago during the Paleocene Epoch. The dinosaurs had just become extinct at the end of the Cretaceous Period. The western half of North America was buckling and folding to create the Rocky Mountains. Large amounts of sediments were forming as water, wind, and freezing worked to break down the mountains. These sediments, mostly sand, silt, and mud, were carried off the eastern slopes by ancient rivers and deposited here in layers. Volcanoes in South Dakota, Montana, Idaho, and across the west were also erupting during this time, spitting out huge amounts of ash. Some of this volcanic ash was blown or carried by rivers into North Dakota and accumulated in standing water. Over time, the sediments turned into the sandstone, siltstone, and mudstone layers now exposed, while the ash layers became bentonite clay.
During the epochs that followed, the land continued to change. Deposition from the mountains in the west continued throughout much of the Eocene, Oligocene, and Miocene epochs. Then as the Pliocene Epoch began, erosion dominated and the layers began to be stripped away. Rivers meandered through broad, shallow valleys across the western Dakotas and eastern Montana plains. Although the rivers changed their courses many times, when the Pliocene Epoch came to a close about two million years ago, one of these rivers existed in almost the same position as the modern Little Missouri River. This river flowed northward to merge first with the ancestral Yellowstone River near Williston, North Dakota, and then merged with the Missouri River, continuing northeastward through Saskatchewan and Manitoba to Hudson Bay.
In the Pleistocene Epoch, the time period of numerous Ice Ages, which began about two million years ago, great continental ice sheets advanced southward from present-day Canada. The ice blocked the flow of the north-flowing rivers, forcing them to create new courses eastward and southward, causing them to empty into the Mississippi River instead of Hudson Bay. By the time the ice retreated, the northern portions of both the Little Missouri and Missouri rivers were entrenched in their new channels. The Little Missouri’s new course to the north followed a steeper course, causing the whole river to flow faster and begin cutting deeply into the land. Slicing easily through the soft sedimentary rocks, the river and its tributaries carved the fantastically broken topography that is today’s badlands.
Geologic processes continue to shape the badlands. Yearly precipitation in the badlands averages 15 inches. Rain, though infrequent at times, usually comes in heavy, erosive downpours. Water running down slope forms gullies, while some soaks into clay-rich rocks and soils. The added weight of water sometimes causes portions of hill sides to break loose and flow downhill.
Sandstone is a classic sedimentary rock composed mainly of sand-sized minerals or rock grains. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, grey, pink, white and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions.
Bentonite is an absorbent aluminium phyllosilicate, impure clay consisting mostly of montmorillonite. The absorbent clay was given the name bentonite by Wilbur C. Knight in 1898, after the Cretaceous Benton Shale near Rock River, Wyoming. The different types of bentonite are each named after the respective dominant element, such as potassium (K), sodium (Na), calcium (Ca), and aluminium (Al). Experts debate a number of nomenclatorial problems with the classification of bentonite clays. Bentonite usually forms from weathering of volcanic ash, most often in the presence of water. However, the term bentonite, as well as a similar clay called tonstein, has been used to describe clay beds of uncertain origin.
Benchmark Placement on Mountain Tops: There may be a large rock at the summit and the benchmark will be cemented in place at the very highest point. Surveyors are concerned with visibility to other survey monuments and thus may place the benchmark near, but not actually on the highest point. The elevation of the benchmark will in these cases be lower than that of the true summit and the position as measured in latitude and longitude will not be that of the highest point. In addition to the primary benchmark, surveyors usually will place two others nearby called reference marks or RM1 and RM2. These will usually be within about 50 feet of the primary mark and be at right angles to each other. They will be marked with an arrow pointing to the primary site to aid in locating it should it be obscured by rocks or plant growth or to help relocate it should it be destroyed. The primary benchmark will most always have the station name and date it was placed stamped onto it. Only rarely is the elevation put on. The name is the one the station goes by in the National Geodetic Survey data sheets. Benchmark names are not unique and may be used again even in the same area so a number is assigned to them called a Permanent Identifier (abbreviated as PID) which consists of two capital letters followed by four numbers. The PID is unique and is never repeated anywhere in the U.S.
Please send the answers to the following questions to Boreal Walker:
- What is just south of the old building that you pass on the two-track?
At the gate:
- What colors and sizes are the rocks on the ground?
- Describe the bands on the bluff face directly in front of you.
- Feel the white sand in the dry creek bed. Describe its texture.
At the summit:
- What is the name of the benchmark?
- How much of the benchmark post has been exposed by erosion?
- Take a picture of your party (optional)
