Geologists tend to concoct unusual names for the things they study. “Dead-ice moraine” may sound odd to some of you. It’s a name for a kind of landform found in parts of North Dakota. Dead-ice moraine sounds odd enough, but can you believe it is found along with things called “doughnuts” and “puckered lips”? First of all, the word “moraine” is an 18th century French word. It was coined by Horace de Saussure to refer to “a heap of earth or stony debris” (de Saussure did not initially realize he was referring to glacial deposits). I’ll explain the “dead” part of dead-ice moraine later.
Dead-ice moraine is also referred to as “hummocky collapsed glacial topography” or “stagnation moraine.” It has irregular topography, formed as the last glaciers were melting at the end of the Ice Age, between about 12,000 and 9,000 years ago. The most extensive area of dead-ice moraine in North Dakota is found on the Missouri Coteau, which extends from the northwest corner to the south-central part of the state (coteau is French for “little hill”) Other extensive areas of dead-ice moraine are Turtle Mountain in north-central North Dakota and the Prairie Coteau in the southeast corner of the state near Lidgerwood. All three areas are uplands that stand above the nearby lower land. The landforms on Turtle Mountain are identical to those on the Missouri Coteau and Prairie Coteau, but Turtle Mountain has a woodland cover, the result of several inches more annual precipitation than the other areas.
North Dakota’s areas of dead-ice moraine generally make for poor farmland as they are rough and bouldery. They do, however, include a lot of excellent rangeland and thousands of depressions, which may contain lakes, ponds, and sloughs known as prairie potholes . The dead-ice moraine of the Missouri Coteau is known as the prairie-pothole region (the so-called North Dakota “duck factory”). The dead-ice moraine is essentially undrained, except locally. No rivers or streams flow for any appreciable distance in any of the three dead-ice regions – Turtle Mountain, the Missouri Coteau, or the Prairie Coteau. Dead-ice moraine formed when glaciers advanced against and over steep escarpments as they flowed onto the three upland areas. The land rises as much as 650 feet in little more than a mile along parts of the Missouri Escarpment, which marks the eastern and northeastern edge of the Missouri Coteau. Similar prominent escarpments border the Prairie Coteau and Turtle Mountain in North Dakota and Manitoba, especially the west side of Turtle Mountain near Carbury. When the glaciers advanced over these escarpments, the internal stress resulted in shearing in the ice. The shearing brought large amounts of rock and sediment from beneath the glacier into the ice and to its surface.
Eventually, as the Ice Age climate moderated, the glaciers became thinner and could no longer flow over higher land, although they kept flowing through lower areas. When the ice on the uplands became detached from still-flowing ice, the glaciers on the uplands stopped advancing and stagnated (or “died”). As the stagnant glacial ice melted, large amounts of sediment that had been dispersed through the ice gradually accumulated on top of the ice, which was several hundred feet thick. The thick covering of sediment on the stagnant glacier helped to insulate the underlying ice, helping to preserve it and prolonging the time it took to melt. As a result, it took several thousand years for the ice to melt. Geologists have determined that insulated, stagnant glacial ice continued to exist on the Turtle Mountain and Missouri Coteau uplands until about 9,000 years ago, nearly 3,000 years after actively moving glaciers had disappeared from North Dakota.
In places where the debris on top of the ice was thickest, the glacier was slowest to melt. If little or no insulating debris covered the glacial ice, melting was quicker and the ice had entirely melted away by 12,000 years ago.
As the stagnant ice on the uplands slowly melted, the glacier surface became more and more irregular. The soupy debris on top of the ice continually slumped and slid, flowing into lower areas, eventually shaping the hummocky, collapsed glacial topography – dead-ice moraine – found today over the uplands. As the stagnant glacial ice melted, and debris slid from higher to lower places, a variety of unusual features resulted. Long ridges formed when sediment slid into cracks in the ice. Such ridges may be straight or irregular, depending on the shape of the cracks. Often, cracks that formed in a rectilinear pattern when the glacial ice was disintegrating, became partly filled with debris that slid into them. Today, we see nearly straight, intersecting ridges, where the ice cracks had been. These ridges are called “disintegration ridges.” Mounds of material collected in holes and depressions in the ice. If the mounds were cored by ice, when the ice cores melted, the centers of the mounds collapsed, forming circular-shaped ridges – “doughnuts.” Some of the doughnuts are breached on two sides because the debris cover on a mound of ice slid off two sides of the mound. Some geologists have referred to such features as “puckered lips.” Wherever part of the covering of debris slid off an area of ice to a lower place, the newly exposed ice then melted more quickly transforming what had been a hill into a hole or depression. Such reversals of topography continued until all the ice had eventually melted.
The insulating blanket of debris on top of a stagnant glacier was so thick in places that the cold temperatures of the ice had little or no effect on the surface of the ground. Trees, grasses, and animals lived on the land surface overlying the stagnant glacial ice. As conditions gradually stabilized, water collected in lakes in depressions on the debris-covered glacial ice. Most of the water in the lakes was probably the result of local precipitation rather than from melting ice. Precipitation at the time was greater than it is today, probably 50 or 75 or more inches of rainfall a year. The mean annual temperature was only a few degrees cooler than it is today.
Surrounding the ponds and lakes, the debris on top of a stagnant glacier was forested by spruce, tamarack, birch, and poplar, as well as aquatic mosses and other vegetation, much like parts of northern Minnesota today. This stagnant-ice environment in North Dakota, 10,000 years ago, was in many ways similar to stagnant, sediment-covered glaciers in parts of Alaska today. Fish, clams, and other animals and plants thrived in the numerous lakes. Wooly mammoths, bear, caribou, wapiti, and other large game roamed the broad areas of forested, debris-covered ice.
During the years I was mapping North Dakota geology, I occasionally came across Ice Age fossils in North Dakota’s dead-ice moraine: caribou bones, mammoth teeth, fossil fish (mainly perch), and various kinds of snails, but paleontologists studying the Ice Age fauna and flora in detail have found many more kinds of Ice Age fossils than I noticed.
Prehistoric people probably lived on the insulated glaciers in North Dakota 10,000 years ago without realizing the ice lay only a few feet below. Or, if they did realize it, they likely accepted it as a normal situation (and I suppose it was normal for that time). Eventually, all the buried ice melted, and all the materials on top of the glacier were lowered to their present position, resulting in the hilly areas of dead-ice moraine we see today.
During my 42 years with the Geological Survey (1962 – 2004), I worked on nearly every facet of North Dakota geology: the rocks that produce oil, gas, coal, gravel, ground water and our other mineral resources. My studies of the glacial sediments near Devils Lake helped me to gain detailed insights into North Dakota’s past climate changes. However, I was always most interested in the origin of the hills and valleys I saw every day as I traveled around the state. I’ve spent a lifetime trying to understand how the land that is North Dakota came to be the way it is. My wife, Mary, and our three children as they came along, lived with me in about 25 North Dakota towns over the years. Our oldest son, Bill, was born in Park River while I was mapping Walsh County, and our daughter, Irene, arrived in Lisbon while I was mapping Ransom County. Paul, the youngest, was born in Grand Forks on the first day of January, when it was too cold to map anywhere. Over the years, we lived, up to six months each, in places like Carrington, Cooperstown, Harvey, Hazen, Mayville, McClusky, Washburn, White Shield, Fort Totten, Fort Yates, Rock Lake, and Turtle Lake. Our summer homes were in towns in about 30 counties, and on four Indian Reservations. We enjoyed every one of them.
Each place was special in some way. North Dakota people are open and friendly, and often interested in geology. When we arrived at a new place, we asked locally if anyone had an apartment for rent and, usually, someone did. In Harvey we rented from the owner of the town bakery—a great choice! In Enderlin, our landlady’s son, a hunter, kept us supplied with pheasants and geese that autumn. In another town, our landlady’s son provided us with wild turkeys (some of them may have been poached—we didn’t ask). In another place, we shared a rental house with some bats. In Fort Yates, the brand-new nursing home was not yet filled and still had room, so that became our home. Our little kids were a hit with the elderly residents. I worked in every part of the state. A “field season” for me usually lasted from sometime in May, beginning when it was dry enough to get around, and ending in November, when the ground was frozen too hard to auger a hole. Just before Thanksgiving, we would move back to our own home in Grand Forks. The day after we got home one year, I raked the yard and put up the storm windows. The next day a blizzard blew, and the snow stayed until spring. Our neighbor, an elderly Norwegian man, commented, in his wonderful accent, “that Bluemle, he always times things right.” Well, I don’t “always time things right,” but I was glad I had that year. For the nearly 25 years that we spent our summers “in the field,” throughout North Dakota, we tended to visualize Grand Forks as a white and snowy “winter wonderland” because we weren’t around much to enjoy it in the summer time. Mary and I claim some important knowledge and understanding of North Dakota, apart from the geology. While mapping, I noted stands of chokecherries, wild plums, buffalo berries and juneberries. That valuable information went on my field maps, right along with the geology, as did the locations of the best places to buy sausage and kuchen.
Most of the photos I will post on this website will illustrate landforms. I hope they will help readers appreciate and understand the geologic processes that shaped our modern landscape. I took most of them during the summers of 2009, 2010, and 2011 while we traveled throughout the state. The notion to travel around the state in the summer as kind of a “post-retirement” project turned out to be a great decision. To provide purpose, I took photos of geologic features. During some of our trips around the state we got a little more “off the beaten path” than I intended. One day, I drove along a road on the Missouri Coteau that became a trail, and eventually a narrow, mostly washed-out path with no place to turn around easily, so I kept going. Finally, we came to a barricade, so I stopped and walked around it to read the hand-printed sign: “Do Not Enter: Road Impassible.” The seven miles I had just driven were impassible! I dug out a couple of the steel fence posts, drove to the “good” side of the barricade, and replaced the posts and sign. Another day, I walked over to a fence line, took a picture, and stepped in a badger hole and broke my foot. Still another time, we stopped to admire a herd of longhorn cattle, standing on the road, surrounding us. I thought one was particularly handsome so I took his picture through the open window on the passenger side of our van. I felt something cold, turned around, and found myself nose to nose with a cow that had gotten her head in through the open window as far as her horns allowed. I presumed she probably wanted her picture taken too, so I snapped her as well.
Many geologists move from country to country around the world; we moved from county to county around the state of North Dakota. Unspoiled prairies and buttes, rivers and lakes, wildflowers and wild fruit are everywhere. Wildlife abounds. Gravel trails lead to broad horizons. Late afternoon summer
showers are followed by spectacular sunsets. The prairie landscapes are multi-dimensional. Their breadths, elevations and depths reflect geologic events and processes I’ll explore on this website. And the geology is always there. Geology opens the door to another world just beneath the familiar scenes of our everyday lives. It takes us outdoors as we explore the intricacies of our Earth’s history. Mary and I have traveled beyond North Dakota–to most of the states and Canadian provinces and about 20 other countries. Much of our travel has been to enjoy geology. We’ve seen a lot of spectacular geology in places like Montana, Alberta, and Sweden. Scotland is my favorite destination for geology and for the history of the science of geology. Our geology, here in North Dakota, may be more subtle than the places I just mentioned, but it is just as interesting. My career has been satisfying, my work interesting and rewarding. Every day on the job was different for me. Whether it was the glorious summer days in the field, mapping geology, or wintry days I spent in my office, piecing together and trying to understand what I had mapped the previous summer, it was always fascinating.