Bobbie Rice Professor Keeler Geography 219 Paper: South Dakota, Land of Infinite Variety South Dakota: Land of Infinite Variety South Dakota has long been known for its beauty and majestic landforms. Within the borders of this state a person can find mountains, rolling hills, glacier lakes, prairie, sand dunes, buttes, canyons, and wetlands just to name a few. It is because of this that the state has become known has the land of infinite variety. It is easy to appreciate all the beautiful landforms that South Dakota has to offer now in the present day, but how did it get this way, and what was it like before? I would like to take a look into South Dakotas great landforms and regions in the present day, and also explore a brief history of what made them what they are. South Dakota Geologic History Time Periods: Precambrian Era -4 billion years ago to 540 million years ago This time period took place over 540 million years ago all the way up to 4 billion years ago and is the oldest time period in the geologic timescale. According to Geology About, the oldest rocks found in South Dakota occurred during the Precambrian period. These rocks were composed of granite and metamorphic rocks and are found in two different locations in South Dakota, which are the Black Hills and a small area in the eastern part of the State. According to New World Encyclopedia, the core of the Black Hills is made of granite and dates back to 1.8 billion years ago. Although the core of the Black Hills is very old New World Encyclopedia says that there are two locations that have older rock that dates between 2.2 to 2.8 billion years old, which is Elk Creek Granite in the northern hills, and Bear Mountain Complex located in the west central hills. Paleozoic Era -250 to 540 million years ago According to Black Hills Visitor From around the end of the Precambrian time period all through the Paleozoic era South Dakota experienced its first sea which covered areas of the western part of the state first. Seas came and retreated many times over west South Dakota leaving layers of rock behind each time. Cambrian Period- 485 to 540 million years ago- During the Cambrian period South Dakota was mostly eroded and had an overall flat surface. University of Tennessee Geologic Time Scale Chart Mesozoic Era -71 to 250 million years ago Jurassic Period- 144 to 201 million years ago-During the Jurassic period low seas again covered the western part of South Dakota. Cretaceous Period- 143 to 71 million years ago- In the Cretaceous Period, which occurred during the Mesozoic Era, all of South Dakota was completely covered with ocean. According to Northern Education, during the cretaceous period western South Dakota obtained shale, sandstones, and lime stones. Also deposited were thick layers of marine sediments. These sedimentary rocks were deposited over 65 million years ago in a very large inland sea that covered most of this state. According to Geology About, During the Cretaceous period the ocean was so high at this point in time that this part of the continent was flooded with a great sea way. The end of the Mesozoic era is the last time seas covered South Dakota. The end of the Mesozoic era is also when the Black Hills of South Dakota were being created beginning around 70 million years ago. According to Black Hills Visitor overall more than 6,000 feet of rock layers have been removed from the Black Hills over time due to erosion. Cenozoic Era -70 million years ago to Present During the beginning of the Cenozoic Era starting around 70 million years ago until about 40 million years ago the Black Hills were being created in what is known as the Laramide Orogeny. According to MSU Education the Laramide Orogeny is a major tectonic event that was responsible for the mountain building of the Rocky Mountains and the Black Hills of South Dakota. Oligocene Epoch- 23 to 33 million years ago- Streams in Black Hills area could no longer carry the amount of sediment in them . Deposits began to cover the area around the Black Hills until it worked its way up covering a good portion of the hills themselves. During this time less than 2,000 feet of the Black Hills might have actually been above ground. A change in climate or further uplift caused the erosion process to that revealed the hills to what they are today. Pleistocene Epoch- 2 million years ago- Ice Age caused reoccurring glaciers that covered eastern South Dakota off and on. After the glaciers melted they left behind glacial drift and glacial lakes. Holocene Epoch- 10,000 years ago to present- Holocene is the most current geologic epoch, and includes things that have occurred in the last 10,000 years up to the present time. The last glaciation period in South Dakota was the Wisconsin Glaciation period that ended 10,000 years ago. South Dakota Today There are many ways South Dakota could be divided into regions or provinces. Some sources break South Dakota into two halves which would be East River and West River seperated by the Missouri River that divides the state. Others might break it into three sections, The Central Lowlands, The Great Plains and The Black Hills. According to New World Encyclopedia South Dakota is made up of four different land regions. These regions are the Drift Prairie, The Dissected Plains, The Great Plains, and The Black Hills. These four regions are the ones I will use to divide the state into smaller areas. Drift Prairie- The Drift Prairie region takes up the majority of eastern South Dakota. This region of South Dakota contains glacial lakes, low hills, grasslands, lowlands, and wetlands. This land region can be broken down into 3 smaller sub regions, which are The Minnesota River Valley, The Coteau Des Prairies, and The James River Basin. Reoccurring glaciers from the last Ice Age carved and shaped these regions, and most of northeastern South Dakota into what it is today. According to Northern Education this process of Glaciation in South Dakota began in the Pleistocene Epoch around 1.5 million years ago. Glaciers moved across the eastern part of South Dakota several times causing erosion, moraines, glacial drift, lakes, and other land features that make up the eastern part of the state. The last glaciers in South Dakota retreated around 10,000 years ago in what is known as the Wisconsin Glaciation period. The Minnesota River Valley is located in the far north eastern part of South Dakota. This areas land characteristics are the result of an ancient river that flattened it out and glaciation which eroded and carved it. According to Princeton Education, during the Wisconsin Glaciation period this area of South Dakota was a drainage system for the largest glacial lake to occupy North America, Lake Agassiz. The Minnesota River was just one of the numerous drainages for this massive ancient lake. According to Geography of South Dakota, Lake Agassiz shaped the land of the Minnesota River Valley by leaving a series of low beach ridges behind, and also a narrow trench which is now occupied by two main lakes, which are Big Stone Lake and Lake Traverse. The Minnesota River Valley is covered extensively with water from these two lakes with the remainder of its surface lowland with two main moraines, which are the Gary Altamont and Big Stone moraines. The Coteau Des Prairies is found bordering the west of the Minnesota River Valley. This land area is known for its beautiful grassy low hills and many glacier lakes. According to Netstate Coteau Des Prairies meaning prairie hills, got its name from French fur traders. This 200 mile long flat iron shaped plateau is bordered by the Minnesota River Valley on the east and the James River Basin on the west. The main drainage system for Coteau Des Prairies is the Big Sioux River. According to Geography of South Dakota most of the glacial lakes in this area can be found to the west of the Big Sioux River due to drainage differences during the melting of the last glaciers. Geography of South Dakota also states it is believed that Coteau Des Prairies exists due to ancient stream valleys that gave the plateau its shape. The James River Basin is the area found in between Coteau Des Prairies and Coteau Du Missouri. The area extends along The James River, which is the main drainage system for The James River Basin. The James River Basin is characterized by highly eroded lowland, marshes, wetlands and glacial lakes. It is lower in elevation than both coteau areas that border it. According to Geography of South Dakota, its difference in elevation from the surrounding land made it easier for glaciers to become thicker in it, resulting in significantly more erosion. The Dissected Till Plains- This region of South Dakota is located on the south eastern part of the state. Just like most the land found in the eastern portion of the state, the Dissected Till Plains were formed due to glaciation. According to FamilyPedia the rolling hills and fertile land of the Dissected Till Plains region was formed by an accumulation of left behind loess from the Wisconsin Glacial period. The Great Plains- The Great Plains region covers most of the western half of South Dakota. Physical characteristics of this region are grassy plains, rolling hills, buttes, sand hills and canyons. According to Wikapedia, erosion from the Black Hills, marine skeletons that fell to the bottom of an ancient low sea that covered this area, and volcanic material all contribute to the geology of this region. One of the most noted land features of The Great Plains region is the Badlands. According to North Dakota State University, the Great Plains has been treeless for the last 8,000 to 10,000 years, but was not always like that and was once covered with spruce forest 12,000 to 14,000 years ago when the last glacier sheet was present. The Geography of South Dakota breaks this region into six smaller sub regions which are The Northern Plateau, the Southern Plateau, The Missouri River Trench, The Coteau Du Missouri, The Pierre Hills, and the Sand Hills. The Coteau Du Missouri area lies in between the James River Basin to the east and the Missouri River to the west. It is 200 miles long with some areas getting 75 miles wide at its north end all the way down to 25 miles wide at its southern end. This area is known as the western equal to the Coteau Des Prairies. The Coteau du Missouri is a part of the Missouri Plateau that has been separated by the Missouri River trench. Coteau du Missouri, just like a big portion of eastern South Dakota, was shaped and changed by glaciation. The Coteau du Missouri area is marked with many moraines, hills and valleys, and areas of lowland. According to the Geography of South Dakota a special feature of this sub region is sags, which are former west to east running ancient stream valleys that have been covered with glacial drift. There are five sags that run through the Coteau du Missouri. The one most distinct of the sags is one that lies to the north of the Ree Hills, and is known as the Great Ree Valley. According to Geological Survey Professional, the main body of the Coteau du Missouri is made up of Pierre Shale, with the exception of quartzitic sandstone that caps some of the hills and buttes. There are many hill formations within the Coteau du Missouri area. The highest of them is a great mesa known as the Ree Hills, which are located in hand county and are 2,200 feet high. The Missouri River Trench area is located right through the middle of the state going down in a general south eastern direction. The Trench separates the Missouri Plateau from the Coteau du Missouri. The Missouri River Trench is the area surrounding the Missouri River as it goes through South Dakota. The width of the trench is around a mile wide with some areas up to four miles wide toward the north. According to the Geological Survey Professional, the side slopes of the Missouri River Trench are steep, dissected bluffs ranging in height from 300 to more than 600 feet above the river. During the last glaciation period an ice sheet that covered a big portion of South Dakota blocked the ability of streams to flow from west to northeast forcing the streams in a southeast path along preexisting valleys, which is how the Missouri River got its current path. Even though there are still signs of change from glaciation in the Missouri River Trench, it is at this sub region that the effects of glaciation in South Dakota start to become much less noticeable. In fact if a person looked at a map that showed the border of what the glaciers covered in South Dakota, it follows very closely to the Missouri River line. Located to the west of the Missouri River Trench is the Pierre Hills sub region. Physical features of the Pierre Hills are smooth rounded hills and ridges that descend and ascend in a rollercoaster like fashion. Geologists E.P. Rothrock wrote “The heart of the region, between the Moreau and White River valleys, is a land of smooth rounded hills which give travelers in our modern high-speed cars some of the thrills of the roller-coaster in spite of the highway engineer’s ingenuity in leveling steep grades.” This area is made up of Pierre shale which breaks down into a sticky clay known as gumbo. It is for this reason that the Pierre Hills sub region is known as the gumbo area. Among the smooth hills are occasional buttes. The most famous of these is Medicine Butte, which is 400 foot tall and is located in Lyman County. A special land feature found in the Pierre Hills is the tepee butte, which is cone shaped and ranges from three feet up to thirty feet. The tepee butte got its name due to its resemblance to the Native American tepee. The Northern Plateau sub region lies west of the Missouri River and covers the north western part of the state. This land is characterized by a series of sandstone capped terraces starting from the Missouri River to the border of Montana. Author E.P. Rothrock described this part of South Dakota as the Cretaceous Table Lands. This is due to the fact that each of the steps or terraces was caused by a sandstone bottom being left behind during the retreat of the last sea in South Dakota during the Cretaceous period. There are many buttes that occur throughout the Northern Plateau sub region. The Cave Hills located in Harding County are the most famous in this area. The Southern Plateaus are located west of the Missouri River and South of the Pierre Hills. The physical characteristics of the Southern Plateau sub region consists of flat grass lands, deep stream cut valleys, canyons, tables and buttes. This sub region contains the famous Badlands of South Dakota which can be found in the northern part of the Southern Plateaus region. Although many badlands formations are located here the Big or White River Badlands are the most recognized. The Badlands were formed by the erosion of sediments that according to National Park Service were deposited beginning 69 million years ago when the area was covered by sea. NPS says that erosion of the Badlands however did not begin until half a million years ago. According to New World Encyclopedia, during the Oligocene Epoch that took place between 25 and 40 million years ago, conditions for preservation of extinct animals was excellent in the Badlands. Badlands National Park currently contains the richest Eocene/Oligocene Epoch fossil beds in the world. The southern section of the Southern Plateaus region contains wide buttes and mesas and is known as the Tables. According to The Geography of South Dakota, some of the famous tables are Cuny Table, Sheep Mountain Table, and Hart Table, which are over 5 miles in length and width, and are 400 feet high. The Sand Hills sub region is located at the southern border of South Dakota in the middle of the western half. This is the smallest of all the regions in South Dakota. The Sand Hills region in South Dakota is an extension of the Nebraska Sand Hills. The area extends along the border of South Dakota and Nebraska for about 80 miles with the longest part of it extending into South Dakota for about 12 miles. The Sand Hills physical characteristics are sand dunes with areas in between the dunes of flat ground, marshes and lakes. The Sand Hills are ranch country and are mostly used for grazing cattle. There are however not many ranches located there. Author James M Crowley wrote, “The Bennett-Mallette-Todd Counties, South Dakota, County-Wide Directory has detailed maps of roads, towns, and farm/ranch headquarters. It reveals that the South Dakota Sand Hills have no towns, no railroads, few roads and few ranch headquarters.” So overall the Sand Hills are a fairly unoccupied place of beautiful rolling sand dunes covered with grass, with flat land, marshes and lakes in between them. Unfortunately has Author James M Crowley said in his article The South Dakota Sand Dunes, many tourists never see them because they are never advertised the way the Black Hills, Badlands or other more famous destinations are. The Black Hills- The Black Hills Region is a low mountain range located at the far western side of South Dakota. According to Netstate it covers an area of 6,000 square miles with mountains that rise from 2,000 to 4,000 feet high. Located in the core of the Black Hills, Harney Peak is the highest point in South Dakota with a height of 7,242 feet. The Black Hills got its name due to the fact the pine forest that cover it gives off the appearance of hills being black especially when viewed from a distance. According to Geology About, The Black Hills were created 70 million years ago in the Cretaceous age. Eventually the Black Hills eroded exposing the 2 billion year old Precambrian core, which is the some of the oldest rock in the state of South Dakota. The Black Hills are surrounded with younger marine rocks from the Paleozoic and Triassic periods from when ocean covered this area. Many fossils of marine life and rocks from these oceans can still be found in the Black Hills and surrounding area. During the uplift and creation of the Black Hills, volcanoes were present. According to Black Hills Visitor, during the later stages of uplift molten lava was forced upwards created many of the mineral deposits found in the Black Hills such as gold and silver. The Black Hills also contains copper and lead. South Dakota has gone through many different stages and changes to get where it today. The different regions and landforms tell a story of South Dakotas History. Whether a person enjoys mountains, prairies, lakes, or soft rolling hills South Dakota seems to have something for everyone. Work Cited 1. South Dakota Department of Tourism. South Dakota Great Faces Great Places. Travel SD, Updated 2014. Web. April 21, 2014 http://www.travelsd.com/Destinations 2. Rieger, B. A. (2004). Demographics of western south dakota wetlands and basins. (Order No. 1421219, South Dakota State University). ProQuest Dissertations and Theses, , 174174 p. Retrieved from http://search.proquest.com/docview/305121776?accountid=9609. (305121776). 3. Stoffer, Philip Ward. 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