The work of John Bluemle PhD

Drainage Diversion

14-KILLDEER MOUNTAINS

 

Pembina mountain, geology, North Dakota

Fig. 14-A. View to the east from Pembina Mountain over the Red River Valley of the North. The town of Mountain is about three miles in the distance. The town’s name may have alluded to the view of the “mountain” to the west as the town itself was on the relatively flat shore of Glacial Lake Agassiz. Photo June, 2009.

Several years ago, billboards were posted around North Dakota in an effort to entertain and catch motorists’ attention. One of them, outside of Mandan, read “North Dakota Mountain Removal Project Completed.” The billboard referred to the image many people have of North Dakota as a flat and featureless land, but the sign ignored the fact that, within our borders are at least half-a-dozen features bearing the name “mountain.” Was the removal project a failure?

Fig. 14-B. Tracy Mountain, 8 miles southwest of Fryburg in Billings County. The caprock is probably Sentinel Butte Formation.

Fig. 14-B. Tracy Mountain, 8 miles southwest of Fryburg in Billings County. The caprock is probably Sentinel Butte Formation. Photo September 9, 2009.

 

 

 

 

 

One of our mountainous areas is the Killdeer Mountains in western North Dakota, about 40 miles due north of Dickinson. Another is Turtle Mountain, home of the International Peace Garden on the North Dakota-Manitoba border. (Turtle Mountain is singular, not plural; I’ll explain later). It may seem odd that the Killdeer Mountains, Turtle Mountain, and several other features in North Dakota are called “mountains.” The idea may be related somewhat to scale. When viewed by a person who has recently traveled over eastern North Dakota, the features may be  impressive, but I wonder what they might have been named if more of our settlers had come via Wyoming or Montana.

Killdeer Mountains, North Dakota, geology

Fig. 14-C. View of North Killdeer Mountain in Dunn County. Photo August 5, 2009.

We have several more places in North Dakota that bear the name “mountain.” The town of Mountain in Pembina County was settled by Icelanders in 1873. Mountain is situated on the former shoreline of glacial Lake Agassiz, and the view from there, over the Red River Valley, is impressive. Just north of Mountain, the hilly area along the Pembina River Valley in northeastern North Dakota is sometimes referred to as “Pembina Mountain,” but the term “Pembina Hills” is commonly used as well. The steep escarpment is also referred to as the “Pembina Escarpment” or “Manitoba Escarpment.” Pioneer geologist David Dale Owen, when he traveled through the Red River Valley in 1848, commented on Pembina Mountain thus: it is “in fact no mountain at all, nor yet a hill. It is the terrace of table land – the ancient shore of a great body of water that once filled the Red River Valley.” People have been critical of the kind of mountains we have in North Dakota ever since! (Owen was from Indiana).

Killdeer Mountains, North Dakota, geology

Fig. 14-D. View toward the east of South Killdeer Mountain. Photo August 5, 2009.

Other named “mountains” in North Dakota include Devils Lake Mountain in southeastern Ramsey County, Blue Mountain in western Nelson county, Lookout Mountain in northeastern Eddy County, and the Prophets Mountains in western Sheridan County. All of these features are ice-thrust hills or complexes of ice-thrust topography that stand as high as a few hundred feet above the surrounding areas. Near Medora, in Billings County, we have Tracy Mountain, but we don’t have many “mountains” in southwestern North Dakota – in that area the term “butte” is used more often. Several hundred formally named features called “hills” or “buttes” are found in North Dakota, as well as a few “points” and “ridges.” Many of these are at least as impressive as some of our mountains. We also have many features that fit the formal definition of a mesa, but very few of them have been referred to as mesas. I won’t dwell any longer on the vagaries of naming topographic features. The names don’t necessarily make much sense. We do manage to communicate, at least if we stay close to home. This article will deal mainly with the Killdeer Mountains and I will follow it with an article on Turtle Mountain. Both features are of considerable scenic beauty no matter what you want to call them and both have interesting stories to tell. The Killdeer Mountains 

Arikaree Formation, wormy marker bed, North Dakota, geology, Killdeers

Fig. 14-E. Arikaree Formation, a highly resistant, freshwater limestone that forms a caprock on the Killdeer Mountains. This formation is known also as the Wormy Marker Bed. The rock has holes caused by burrowing mollusks (clam-like animals similar to modern shipworms) before the sediment solidified. Photo September 25, 2009.

        The Killdeer Mountains consist of two large, flat-topped buttes in Dunn County. They cover an area of 115 square miles and rise from 700 to 1,000 feet above the surrounding plains. The entire elevated Killdeer Mountain region is about nine miles long and six miles wide. The highest elevation in the area is 3,314 feet, which is 192 feet lower than the highest point in the state (White Butte). The term “Killdeer” is presumably a translation of a Sioux phrase: “Tah-kah-p-kuty” (the place where they kill the deer).

Arikaree boulders, geology, North Dakota, Killdeer

Fig. 14-F. The slopes of the Killdeer Mountains are littered with large numbers of boulders that have broken away from the Arikaree Formation caprock and rolled down the slopes around the buttes. They are especially numerous on the south slope of South Killdeer Mountain. Photo September 25, 2009.

 

 

 

 

 

The caprock on the Killdeer Mountains consists of a 300-foot-thick sequence of siltstone, sandstone and carbonate beds that belong to the Miocene-age Arikaree Formation. One of the most conspicuous, ledge-forming units within the Arikaree Formation is found about 150 feet below the caprock. Known as the “burrowed marker unit” or “wormy marker bed,” it is a sequence of hard, erosion-resistant interbedded siltstone and sandstone with some carbonate lenses (the burrows in the bed were dug by clams living in the sediment before it hardened; the organisms that did the digging were similar to modern “shipworms”). The Arikaree Formation lies on top of the Eocene-age Chadron Formation, a sequence of yellow to green sandy mudstone, clayey sandstone, and pebbly sandstone. The tree-covered, slopes around the flanks of the Killdeer Mountains are mainly landslide topography, consisting of materials that have fallen or slid from higher up. A little farther away, the grassy or farmed, less-hilly areas are underlain mostly by the Golden Valley Formation, a Paleocene to Eocene-age rock unit. The Paleocene Sentinel Butte Formation, which underlies the Golden Valley Formation beneath the Killdeer Mountains, occurs at the surface in a broad area surrounding the Killdeer Mountain upland.

caprock, Arikaree formation, North Dakota, geology, Killdeer

Fig. 14-G. This boulder on a south slope of the Killdeer Mountains has broken off of the Arikaree Formation caprock (Wormy Marker Bed) near the top of the butte and rolled down the butte. Photo September 25, 2009.

The two main buttes that make up the Killdeer Mountains coincide with areas that were once lakes in which sandy and limy sediments, along with some stream deposits, accumulated during Miocene time. Repeated volcanic eruptions in the Rocky Mountains to the west produced large amounts of ash, which blew eastward, fell to the ground, and washed into the lakes, forming tuffaceous (meaning they contain volcanic ash) sandstones.

Battle of Killdeer Mountain, geology, North Dakota

Fig. 14-H. This sign overlooks the site of the Battle of Killdeer Mountain, at the south end of the Killdeer Mountains. The site is 8 ½ miles northwest of the town of Killdeer. Photo August 5, 2009.

 

 

 

 

 

A new erosion cycle began about five million years ago, long after the lakes had filled with sediment, and dried up. The relatively hard tuffs and freshwater limestone and sandstone beds that had been deposited in the Miocene lakes were much more resistant to erosion than were the surrounding sediments. Because of their resistance to erosion, these hard materials remained standing above the surrounding area as the softer Golden Valley and Sentinel Butte sediments were eroded away by streams and rivers. The Killdeer Mountains, with their resistant caprock, are the result of that erosion; they are the modern manifestation of ancient lake beds. The topography has undergone a complete reversal; areas that were once low are now high due to their resistance to erosion.

medicine hole, killdeer mountain, geology, North Dakota

Fig. 14-I. This is the opening in the rocks that serves as the entrance to Medicine Hole, on top of South Killdeer Mountain. Photoscan 1970s photo.

Two sites in the Killdeer Mountains are of particular interest. The Killdeer Mountain Battle State Historic Site is located on the southeast edge of the Killdeer Mountains, seven miles northwest of the town of Killdeer (Section 34, T. 146 N., R. 96 W.). The Battle of the Killdeer Mountains took place on July 28, 1864 when General Sully and 2,200 troops used artillery on 6,000 Teton and Yanktonai Sioux in revenge for the uprising of Santee Sioux in southern Minnesota. Sully decimated the Sioux, killing many of them and destroying their camp and equipment. Less than a year earlier, on September 3, 1863, Sully had accomplished a similar feat at the Battle of Whitestone Hill, where his troops killed, captured or wounded 300 to 400 Sioux Indians. Medicine Hole is, indeed, a hole in the ground, but it is not a cave in the traditional sense because it did not form as most caves do. No solution of carbonates was involved, and there are no stalactites or stalagmites. It is, rather, a crack in the ground, where a large block of material has begun to fall away from the main body of the southern butte of the Killdeer Mountain. Medicine Hole is located on private land and, as I write this, in 2015, the area is not open to public access. Please respect the wishes of the land owner. The Killdeer Mountains support the largest deciduous forest in southwestern North Dakota, except for the forests on the floodplains bordering the major rivers. The Killdeer Mountain forest consists largely of aspen and oak, with some ash, elm, birch, and juniper, along with shrubs such as chokecherry, willow, plum and buffaloberry. The forest is interesting in that it contains species that tend to be found in more boreal settings, areas that may be 200 miles or more to the northeast.

frost wedge, glaciation, Killdeers, North Dakota, geology

Fig.-14-J. Photo of a frost wedge in pediment sediments along the west side of Killdeer Mountain. The geologist’s finger is pointing to the wedge formed when the frost forced sand and gravel apart during the Ice Age when the area was a tundra environment.* Photoscan, JPB photo, 1970s.

In summary, the Killdeer Mountains are an erosional feature, preserved because of their resistant caprock of tuffaceous sandstone and limestone. Erosion of the area began in late Miocene time, and continued into Pleistocene time, resulting in gravel-covered, flat, sloping surfaces (pediments) around the flanks of the Killdeer Mountain uplands. These gravel deposits, up to ten feet thick, were derived from the sandstone and limestone beds higher up in the Killdeers. The gravels are themselves resistant to further erosion and they help to retard the rate of the ongoing, modern erosion cycle. The current erosion cycle began when the nearby Little Missouri River was diverted by a glacier from its northerly route so that it flowed (flows) eastward to its modern confluence with the Missouri River. As a result of the diversion, and the resulting steeper gradient over which it flows, the Little Missouri River began to erode vigorously, carving the badlands through which the modern river flows today. Although the Killdeer Mountains show no evidence of ever having been glaciated, their modern topography dates largely to the Pleistocene. Old ice wedges can be seen in the pediment gravels in places, testimony to the time when the area was subjected to tundra conditions during one or more of the glacial epochs. There were no glaciers over the Killdeers, but continuous frigid conditions provided a tundra ecosystem. *Frost WedgesFrost wedges are common,  but many areas of patterned ground that have been interpreted to be frost polygons are really dessication cracks developed in silcrete. These are much older than frost wedges, such as this one, which formed in loose materials.

9-HOW THE MISSOURI RIVER FORMED

geology, North America glacial map

Fig. 9-A. Drainage map of central North America, east of the Mississippi River: Bell River drainage system. Diagram: 1-29-2015

Agreement on the origin of the name of the “Missouri” River is difficult because too many contradictory explanations exist. The name apparently comes from a Siouan Indian word, “ouemessourita” or “emissourita,” translated by early French explorers as “those who have wooden dugout canoes,” or “river of the large canoes,” or “town of the large canoes,” or any of several other possibilities. One source says the term was the name the Illinois Indians used for the native people who lived in the Mississippi River Valley, probably mainly on the eastern (Illinois) side of the river; another source says they lived in what is now the State of Missouri.

The Missouri River originates near Three Forks, Montana, where the Gallatin, Jefferson, and Madison rivers come together. It flows 2,341 miles to St. Louis, where it joins the Mississippi River. This makes the combined Missouri-Mississippi River, at 3,709 miles, the fourth longest river in the world, after the Nile, Amazon, and Yangtze. The entire length was once riverine environment but, due to the dams that have been built along its route, approximately a third of the length is now reservoirs – lake environment rather than river. Listed from upstream to downstream, the dams are: Fort Peck in Montana, Garrison in North Dakota, Oahe, Big Bend, and Fort Randall in South Dakota, and Gavins Point on the South Dakota-Nebraska border.

Along with its valley, the Missouri River is largely a product of glaciation. Before North America was glaciated, all the drainage in North and South Dakota, eastern Montana, and northern Minnesota was north or northeastward into Canada. There was no “Missouri River” carrying drainage from the northern mid-continent region to the Gulf of Mexico. The way I define the Missouri River requires that its water ultimately reach the Gulf of Mexico as it does today, and that it carry water draining from the Rocky Mountains and northern Great Plains. Prior to glaciation, no such river existed. Why is the situation today so different than it was before the Ice Age?

North Dakota, geology, glacial drainage

Fig. 9-B. Map of North Dakota showing the drainage pattern prior to glaciation. All rivers flowed north or northeast into Canada. The Missouri River Valley did not exist (except for short segments that correspond to portions of valleys such as the Knife and McLean River valleys (see text). Diagram. 1-29-2015

The modern Missouri River Valley in North Dakota consists of several discrete valley segments that differ markedly from one another. Some of the segments are broad: six to twelve miles wide from edge to edge, with gentle slopes from the adjacent upland to the valley floor. Others are narrow: less than two miles wide, with rugged valley sides – even badlands slopes in places. Most of the wide segments trend from west to east whereas the narrow segments are mainly north-south. The Bismarck-Mandan area is one of only a few exceptions, and I’ll explain why shortly.

The west-east segments of the Missouri River Valley are wide because they coincide with much older valleys that existed long before the area was glaciated. Old, mature river valleys, which formed over long periods of time (hundreds of thousands or millions of years), tend to be broad with gentle slopes. Younger valleys formed more quickly (tens of thousands of years), and are usually narrower with steeper sides. An example of a wide segment is the forty-mile-long, west-east segment of the Missouri River Valley upstream from Garrison Dam. This part of the valley, now flooded by Lake Sakakawea, was once the route of a river that flowed east to Riverdale. However, the river didn’t turn south at Riverdale, as it does today. Rather, it continued eastward past Riverdale, and on past Turtle Lake and Mercer, flowing into northeastern North Dakota. For convenience, I’ll refer to this ancient river as the “McLean River.”

McLean River, geology, North Dakota

Fig. 9-C. . Map showing a portion of the route of the preglacial “McLean River,” which flowed eastward through a broad valley that passed between Garrison and Riverdale, to the Turtle Lake area, and on into Sheridan County. When the McLean River valley was blocked by a glacier (to the east of the area shown on this map), a proglacial lake formed in the valley. When the lake overflowed southward from a point near Riverdale – at the site of the modern Garrison Dam – a narrow diversion trench was cut. The modern Missouri River flows through this diversion trench. Diagram: 1-29-2015.

East of U. S. Highway 83, the route of the old McLean River valley is a broad, low area, partly buried beneath tens to hundreds of feet of glacial sediment. Lake Audubon, Turtle Lake, Lake Brekken, Lake Holmes, Lake Williams, Lake Peterson, Pelican Lake, Blue Lake, Brush Lake, and other smaller lakes mark the former route of the McLean River through eastern McLean County. However, continuing farther east, the McLean River valley becomes so deeply buried beneath glacial deposits that it would be nearly impossible to know its route from a study of the surface topography. Fortunately, hundreds of test holes were drilled during studies of the ground water resources of the glacial deposits so we have a good idea of the route the river followed into northeastern North Dakota.

Another wide, west-east trending segment of the modern Missouri River Valley, between Stanton and Washburn, is an eastward continuation of the modern Knife River. Prior to glaciation, the Knife River flowed east in its modern valley to Stanton, but it continued eastward from there, past Washburn. A few miles east of Washburn it turned slightly northeastward. The ancient Knife River joined the McLean River near the town of Mercer and the combined Knife-McLean River continued northeastward to the Devils Lake area. It then flowed north along the east side of Turtle Mountain area into Canada.

Still another wide segment of the Missouri River Valley in northwestern North Dakota extends from near the modern Missouri River /Yellowstone River confluence, northeastward to Williston.

Fig. 9-D. Map showing the Missouri River Valley at Bismarck-Mandan. South of Bismarck (south of the railroad), the valley is wide because it corresponds to the old, northeast-trending preglacial valley of the Heart River. North of the city, the valley is narrow with quite steep sides. This part of the valley was formed when an ice-dammed lake to the north, in the preglacial Knife River valley, overflowed from a point near Wilton. A similar ice-dammed lake existed in the Heart River valley east of Bismarck – the glacial Lake McKenzie. Diagram: 1-29-2015.

Fig. 9-D. Map showing the Missouri River Valley at Bismarck-Mandan. South of Bismarck (south of the railroad), the valley is wide because it corresponds to the old, northeast-trending preglacial valley of the Heart River. North of the city, the valley is narrow with quite steep sides. This part of the valley was formed when an ice-dammed lake to the north, in the preglacial Knife River valley, overflowed from a point near Wilton. A similar ice-dammed lake existed in the Heart River valley east of Bismarck – the glacial Lake McKenzie. Diagram: 1-29-2015.

This six-to-eight-mile-wide section of the valley coincides with the pre-glacial route of the Yellowstone River through that area. Prior to glaciation, the Yellowstone River continued to the north, past Williston, following a route that is now mainly buried. The pre-glacial route coincides with the modern route of the Little Muddy River as far as Zahl, about 30 miles north of Williston. North of Zahl, the old Yellowstone River valley into Canada is so deeply buried that its route is known only through drill-hole data. The river entered Saskatchewan about six miles north of Crosby.

The Missouri River Valley between Williston and New Town, now flooded by Lake Sakakawea, follows the same route as did an east-flowing, mid-Ice Age — but probably not pre-glacial – river. This part of the Missouri River Valley is somewhat narrower than most other east-west segments of the valley in North Dakota, and it is also younger than most of them. It is a continuation of a mid-Ice Age river that flowed east from Montana. In Montana, the route of this river coincides with the modern route of the Missouri River past Wolf Point, Poplar, and Culbertson. The Montana segment of the mid-Ice Age river joined the north-flowing Yellowstone River near Buford.

At Bismarck-Mandan, the Missouri River Valley is about two miles wide at the Interstate Highway 94 crossing, but on the south side of Bismarck the valley broadens to six miles wide. The widening southward seems contrary to my earlier comment that north-south segments of the valley tend to be narrow. There is a reason for this exception though. The valley widens at Bismarck-Mandan because, prior to glaciation, the Heart and Little Heart rivers, which today flow into the Missouri River, joined a few miles east of Bismarck. The combined (preglacial) Heart/Little Heart River continued flowing eastward, joining the Cannonball River in southern Burleigh County, near Moffit. The old, combined Heart/Little Heart valley still exists as a broad lowland south and southeast of Bismarck. It is now a wide spot in the Missouri River Valley.

The Heart/Little Heart river system was probably dammed several times by glacial ice advancing westward. Each time a glacier advanced, a lake formed ahead of – west of – it in the Heart/Little Heart valley. The lake (or lakes) are referred to as glacial Lake McKenzie. At least once, and possibly several times, glacial Lake McKenzie overflowed, carving what is now the Missouri River valley south of the Bismarck-Mandan area.

Missouri River, Fort Lincoln

Fig. 9-E. Photo of the Missouri River at Fort Lincoln State Park south of Mandan. The river is shown in flood stage in August of 2011.Photo: 8-21-2014.

When the (preglacial?) Heart River flowed eastward, through the Bismarck area, it deposited a thick gravel deposit which now lies buried about 100 feet beneath the Missouri River. Bismarck’s new (2013) water-intake structure withdraws ground water from this old Heart River gravel deposit.

When the McLean River valley was blocked by a glacier in the Riverdale area midway through the Ice Age, a large proglacial lake formed ahead (to the west) of the ice in the valley. This lake might be considered to be the “original” Lake Sakakawea: an early ice-dammed lake that predated the Corps of Engineers version of Lake Sakakawea by thousands of years. When the lake overflowed, near where Garrison Dam is today, the resulting flood quickly carved a narrow spillway trench south to the Stanton area.

Similarly, the Knife River, which flowed past Stanton and on to the Washburn area, was dammed by glacial ice just east of Washburn and the valley was flooded upstream beyond Washburn. The resulting lake overflowed and spilled southward into the Burnt Creek-Square Butte Creek drainage, carving a narrow trench from a few miles east of Washburn to the Bismarck-Mandan area. The modern Missouri River flows in that trench today.

And, as I noted, when the Heart/Little Heart River was dammed by a glacier, which probably advanced as far west as Sterling, glacial Lake McKenzie formed. The lake overflowed southward, forming a new valley, now flooded by the northernmost part of Lake Oahe.

The youngest and narrowest segment of the Missouri River Valley in North Dakota is at New Town, between Four Bears Bridge and Van Hook Bay. As recently as 13,000 years ago, a glacier blocked the Missouri River from its route around the north and east side of New Town. The old river route (prior to 13,000 years ago) is now a broad valley, known as the “Van Hook Arm,” flooded by Lake Sakakawea. The glacier dammed the valley, causing a lake to form upstream (to the west) of the point of blockage. Thick layers of lake sediment, known as the “Crow-Flies-High silt,” were deposited in the ice-dammed “Crow-Flies-High Lake.” Crow-Flies-High Lake extended westward from the New Town area to near Williston. In many places between these two cities, exposures of the bedded lake silt deposits occur at elevations as high as 70 feet above the modern, maximum reservoir level (1850 feet) of Lake Sakakawea. The lake rose until it overflowed southward, cutting the channel now spanned by the Four Bears Bridge.

Other “Missouri” River Routes

Up to now, I’ve tried to explain the origin of the modern route of the Missouri River. That’s not the end of the story though. The modern route of the Missouri River is only the most recent of many routes that earlier “Missouri” rivers followed through North Dakota at various times during the Ice Age. These rivers also carried runoff water from as far away as the Rocky Mountains, through North Dakota, on its way to the Gulf of Mexico. However, most of these routes, mainly in northern and eastern North Dakota, are now buried beneath thick accumulations of glacial sediment. Whatever routes these rivers followed, they had to have flowed generally eastward and southward because their original, northerly and northeasterly routes into Canada were blocked by ice each time glaciers advanced into the state. Test drilling, done to study ground water resources, has helped us identify least least some parts of the old “Missouri” River routes. There are dozens of them.

North Dakota, geology, ancestral Missouri River

Fig. 9-F.Map showing the old route of the Missouri River at New Town (within the dashed lines) and the more recent route, formed when a glacier diverted the river farther southwest (within the solid lines). This diverted loop of the Missouri River is the youngest portion of its valley through North Dakota. It formed about 14,000 years ago. Diagram 1-29-2015

One of several early routes of the Missouri River, determined by test-hole drilling, took the river southward past Cooperstown and Valley City to the southeastern corner of the state. Another route took the river southeastward past Jamestown. In the northern part of the state, rivers like the Yellowstone were diverted from their northerly routes to easterly and southeasterly routes, past places like Columbus, Kenmare, and Minot. These buried valleys can be considered to be early “Missouri” River routes.  The array of buried river valleys is really amazing – and so complicated – and such a great number of possible routes exist, that it is impossible to work them all out. All of them are now buried beneath hundreds of feet of glacier sediment, and most of them have no surface evidence whatsoever.

However, not all of the early “Missouri River” routes through North Dakota are deeply buried. In the western part of the state, a version of a Missouri River formed when an early glacier advanced at least as far southwest as the Hebron area. The margin of that glacier coincided with what is now a prominent, broad valley, known as the Killdeer-Shields channel. The channel extends southeastward from the Killdeer Mountains, past Hebron and Glen Ullin, to the Fort Yates area, crossing the modern Missouri River Valley, and continuing through southwestern Emmons County into South Dakota. No river flows through the Killdeer-Shields channel today, but an early Missouri River flowed in it, perhaps for a longer period of time than the current Missouri River has flowed in its modern route. Interstate Highway 94 crosses the valley about half way between Dickinson and Mandan. Good views of the Killdeer-Shields channel can be seen just north of Richardton and between Hebron and Glen Ullin. Old U.S. Highway 10 and the Burlington Northern Santa Fe Railroad follow the old channel from Hebron to Glen Ullin.

Summary

I realize that my description of the changes in the routes the various “Missouri” Rivers have followed since the Ice Age began is complicated. Even so, it doesn’t begin to account for the evolution of all of the changes in the vast array of routes that rivers followed during the Ice Age in North Dakota.

Most of the narrow, north-south segments of the modern Missouri River Valley correspond to places where glaciers diverted then-existing rivers southward. Glaciers in the central part of the state diverted northeast-flowing rivers, like the Knife, McLean, and Heart-Little Heart, and Cannonball, forcing them to flow southward from the points of diversion, forming the north-south segments of the modern Missouri River. Glaciers advancing into northwestern North Dakota diverted mainly north-flowing rivers, like the Yellowstone and Little Missouri, away from their routes into Canada, forcing them to flow to the east and south.

The modern Missouri River Valley is a “composite” feature, consisting of older, wide pre-glacial segments, formed over long periods of time prior to the Ice Age, along with younger, narrow segments that were cut relatively quickly at various times during the Ice Age. The parts of the Missouri River Valley that extend mainly from west to east are wider and much older than are the narrower segments that extend from north to south. Many of the early “Missouri” River routes followed for varying periods of time during the Ice Age in northern and eastern North Dakota were later buried beneath thick deposits of glacial sediment.

The current route of the modern Missouri River Valley is only the latest in a continuing series. After the next glacier has come and gone, a new version of the Missouri River will likely follow a different route than does the river today.

Lake Sakakawea; New Town; Four Bears bridge; ND geology;

Fig. 9-G. Photo of the Missouri River from Crow-Flies Hill at New town, Mountrail County. Lake Sakakawea floods a narrow, north-south valley that was cut when the Missouri River was diverted southward from its earlier route around the north side of New Town. Photo: 7 -16-2010

8-THE BADLANDS – PART TWO

Badlands erosion,North Unit of Theodore Roosevelt National Park,

Fig. 8-A. Erosion in the Sentinel Butte Formation, North Unit of Theodore Roosevelt National Park, McKenzie County. Some beds have eroded into a “rilled” micro-topography (center of photo), with vertical grooves, while other beds retain their horizontal layering, which forms tabular concretions in places. A lag covering of reddish nodules covers the surface at the base of slopes. Photo: 7-27-11

Rain and melting snow, wind, frost, and other forces of erosion have carved our badlands into intricate shapes. Since the Little Missouri River began to form the badlands, it has removed an enormous amount of sediment from the area. In the southern part of the badlands, near the river’s headwaters and close to Devils Tower in northeastern Wyoming and adjacent Montana, the river has cut down about 80 feet below the level at which it had been flowing before it was diverted by a glacier farther north. Near Medora, the valley floor is 250 feet lower than the pre-diversion level. Still farther downstream, in the North Unit of Theodore Roosevelt National Park and near the confluence of the Missouri and Little Missouri rivers, and nearer to where the glacier diverted it, the east-trending portion of the Little Missouri River flows at a level that is 650 feet deeper than when it was diverted.

The average rates of erosion in the badlands, assuming they started to form about 640,000 years ago, can be calculated as follows:

Headwaters area in Wyoming: 0.15-inch/100 years;

Medora area: 0.5-inch/100 years;

badlands, Bully Pulpit, North Dakota, geology

Fig. 8-B. This view is from the Bully Pulpit golf course near Medora, east of the Little Missouri River. The golden beds exposed in the cliff belong to the Bullion Creek Formation, which is the main geologic formation seen in the South Unit of Theodore Roosevelt National Park. Photo: 9-9-2009.

Confluence area near Mandaree – Missouri and Little Missouri rivers: 1.25 inch/100 years.

These rates may seem tiny but, over time, erosion has removed a huge amount of sediment. Approximately 40 cubic miles of sediment have been eroded and carried away by the Little Missouri River from the area that is now the badlands. Most of that sediment now lies beneath the water of the Gulf of Mexico.

The rates of erosion I’ve noted are long-term averages, but erosion goes on at highly irregular rates. Locally, considering only the past few hundred years, the badlands have undergone four separate periods of erosion and three periods of deposition. Since about 1936, new gullies have been cut to their present depths. It may seem a paradox that, although running water is the main agent of erosion, badlands formation tends to be most intense when water is in short supply. Why? Because erosion tends to be more vigorous during times of drought when the vegetative cover is too sparse to protect the soil from the occasional rain storm or spring snow melt. When precipitation is sufficient for the growth of heavy vegetation, the soil is better protected from severe erosion.

 

Fig. 8-C. Concretion pedestals (“hoodoos”) in badlands topography. The concretions act as caprock, and keep the underlying softer sediments from eroding, resulting in table-like configurations. These examples are in the South Unit, Theodore Roosevelt National Park, Billings County. Photo: 9-10-2009.

Fig. 8-C. Concretion pedestals (“hoodoos”) in badlands topography. The concretions act as caprock, and keep the underlying softer sediments from eroding, resulting in table-like configurations. These examples are in the South Unit, Theodore Roosevelt National Park, Billings County. Photo: 9-10-2009.

Streams and rivers carry sediment away from the area of the badlands, but most of the actual “on-the-spot” erosion is a result of slopewash. In places where vegetation is sparse, the soil and rock materials are easily weathered, forming loose surfaces that slide downslope easily, slumping and sliding during showers or when the snow cover melts.

The Badlands Landscape

The shapes, sizes, and configurations of the hills, buttes, valleys, and other landforms in the badlands are not entirely happenstance. Differences in hardness of the materials result in differences in resistance to erosion. Nodules and concretions help to shape a landscape ranging from beautiful, to desolate – even grotesque. Hard beds of sandstone or clinker cap many of the small buttes. Variations in permeability (permeability is a measure of the ease with which water can move through porous rock) have similar effects; rain and melted snow soak into the more open and permeable sands, resulting in only minimal erosion. When water flows over the surface of tighter, less permeable sediment, such as clay, it abrades and erodes the material, carrying some of it away. The presence or absence and the character of the vegetation also play important roles in governing the rate of erosion. Grass usually helps to control erosion more effectively than does forest vegetation.

The irregular placement of hard nodules and concretions may result in the development of rock-capped pillars, known as “hoodoos,” mushroom-like shapes perched on stalks of clay. In places, slopes are covered by nodules of siderite (iron carbonate). As they weather out of the surrounding materials, becoming concentrated on the surface, the copper-colored nodules form an erosion-resistant armor, which temporarily slows the rate of erosion. Clinker beds are also much more resistant to erosion than are the softer surrounding beds. We commonly see buttes capped by red clinker beds.

Limestone concretion, hoodoo

Fig. 8-D. Pedestal, a small “hoodoo” with a limestone concretion caprock, located about a half mile south of Lake Sakakawea in northern McKenzie County. Pods of such freshwater limestone are common in several of the Tertiary formations found in the badlands. They may occur sporadically or as semi-connected layers and they often form small caprocks, such as this one. Photo: 7-23-2010.

Badlands "Pipes"

Fig. 8-E. Badlands “pipes,” vertical cavities measuring about 15 feet top to bottom. These pipes are located in northeastern McKenzie County, about a half mile south of Lake Sakakawea. A cross-sectional view of a pipe, as shown here, is rare. More often, they are concealed with the only opening at the top (but notice that the tops of these pipes are partially sealed by a concretion. Photo 7-23-2010.

 

 

 

 

 

 

 

 

 

 

 

Erosional “pipes” sometimes form in gullies and ravines where surface runoff is focused. “Piping” results where runoff can flow downward into small cracks and joints.  Pipes are common in places where surface runoff erodes cavities vertically downward through the soft rock. With time, the initial pathways may widen at depth into caves the size of small rooms. The average depth of vertical pipes is about 10 to 15 feet, but some are much deeper. The tops of pipes may be partially concealed making hiking treacherous. I have seen the bones of animals, such as rabbits and deer, at the bottoms of pipes (so far I haven’t seen any human bones). The animals fell into the holes and could not get out.

Conclusion

The geology is only part of the badlands story. The weather and climate, vegetation, animals, birds, insects, sounds and aromas–all of these, along with the human history and the ranching heritage, work together to complete the story of the badlands.

I think the North Dakota badlands are particularly beautiful because of their parklands; wooded areas that occur in draws and on north-facing slopes. Heavy vegetation in the badlands in places like Little Missouri State Park adds to the scenery. Evergreens, such as the Rocky Mountain juniper, ponderosa, and creeping juniper are interspersed with quaking aspen, cottonwood, and poplar. Limber pines are found in the badlands in the southwest corner of the state, near Marmarth.

I’ve hiked and camped in the badlands many times. Evening summer showers accentuate the colors and the clinker beds assume intense shades of red and orange. The fresh, pungent aroma of wet sage and cedar enhance the experience. At night, the stark, intricately eroded pinnacles can seem unreal. In the moonlight or in a night lightning storm, it is easy to imagine the strange shapes as ruins of a magical city, rather than structures of mere sand and clay. Blend in the sound of coyotes conversing and the badlands environment is complete.

Little Missouri River, badlands

Fig. 8-F, Panoramic view of the bend in the Little Missouri River from North Unit of Theodore Roosevelt Park. Materials exposed in cliffs are Sentinel Butte Formation. Photo: 7-27-2011

 

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