The Great Plains are a vast expanse of grass-covered lands found in the central region of North America. They extend over 500,000 square miles (1,300,000 square kilometers) across the states of Colorado, Kansas, Oklahoma, Wyoming, Nebraska, Montana, North Dakota, South Dakota, Texas and New Mexico, as well as the Canadian provinces of Alberta, Manitoba and Saskatchewan. Prior to the 20th century, the region was known as the "High Plains," to differentiate the zone from the "Low Plains" of the Midwest states that are found east of the Mississippi River.
Some 144 million to 65 million years ago, during the Cretaceous Period, the majority of this land was covered by a shallow, temperate sea known as the Western Interior Seaway that effectively split the North American continent in half. The warm sea teemed with life, while many species of animals, mostly mammals, roamed the floodplains. When the primeval sea began to recede some 60 million years ago, it left behind a thick marine deposit inter-mixed with volcanic ash. Over the eons, the clay, sand, silt and ash built up layer upon vertical layer of soil thousands of feet deep.
In a small region of this vast land, located in southwestern South Dakota and within the White River drainage system, the forces of erosion have long been at work and created perhaps the most scenic geological and landscape features found anywhere in the Great Plains. From the grass-covered plains suddenly arise an exposed region of ancient sedimentary strata known as the "badlands."
The term "badlands" has come to describe any area on Earth where soft, sedimentary soil is found in combination with intense rain showers and sparse vegetation. This recipe for colossal erosion creates landscapes of steep slopes, canyons , ravines and gullies that once blocked the movement of people and herds of grazing animals. These badland areas also tend to be a treasure trove of fossils.
The indigenous Lakota people called this part of their ancestral home "Makhosica," which translates literally to mean "bad land." Beginning on the eastern slopes of the Black Hills, the most spectacular acreage of this rugged land was first protected in 1939 as a national monument. In 1978 the Badlands National Park was created, protecting over 244,000 acres of "bad land" from further development or incursion.
The White River Badlands of South Dakota are not only spectacular in their weathered appearance but are equally important to the world of paleontology. Here, ancient horizontal strata lie exposed and the same individual beds of sedimentary rock can be traced from mound to mound, pinnacle to pinnacle, across wide ravines. Viewed in aerial photographs, the bands of colorful sediment look like contour lines on a topographical map.
In the Badlands today, evidence of the ancient Western Interior Seaway appears as a band of grayish-black sedimentary rock. Known as Pierre shale, this layer of rock is a remarkable treasure of Cretaceous Period fossils. Within this layer of marine mud rocks, deposited some 75 million years ago, have been discovered a wide variety of ammonites and mosassaurs, large extinct marine lizards. [T-Rex of the Seas: A Mosasaur Gallery]
Within the upper bands of strata are found one of the world's richest vertebrate fossil beds. Created during the Oligocene epoch some 40 million to 25 million years ago, these fossil beds represent only a short period of Earth's history. The ancient mammals, including the saber-toothed tiger, the three-toed horse, camels, several species of rhinoceros and mammoths, roamed the lush river valleys, often dying in tremendous floods after which they were quickly buried. Conditions then were ideal here for preservation in the deep river sediment and over a long period of time the remains of these creatures became fossils.
About 5 million years ago, this region began a gentle uplift, resulting in the raising and drying of the land. With the uplifting came the forces of erosion wind and rain, freezing and thawing that began to sculpt the landscape seen throughout the White River Badlands today.
Over time the region continued to dry out, creating the semi-arid climate found today. The now sparse, arid vegetation resulted in the rise of a new group of mammals, such as prairie dogs , the American bison, the bighorn sheep and the pronghorn. These animals and more came to this desolate land and thrived in the unique Badlands environment.
Great herds of the American bison (Bos bison) once roamed the region of the Badlands. They were the dominant grazers in the grassland ecosystem of the Great Plains. By the 1880s the great herds of bison had been slaughtered and had disappeared. After some 80 years of absence the American bison was reintroduced into Badlands National Park in 1963. Today a controlled herd of 600 bison once again roam on 64,000 controlled acres of this grass prairie.
A family herd of Bighorn sheep (Ovis canadensis) makes for one of the most spectacular views in the Badlands as they seem to magically scale the steep, rocky pinnacles. Known to have crossed the Bering land bridge from Siberia some 750,000 years ago, they quickly spread across western North America as far south as Mexico. Once hunted to near extinction in 1926, a new herd was reintroduced in 1964 and once again Bighorn sheep are prospering in this ideal, rocky environment.
There are 206 species of birds that have been documented in the Badlands of South Dakota. Sixty-seven of those species are known to nest in this rugged and unique land. The Badlands are located at a crossroad for bird migration. Both western and eastern birds seasonally move through the region. Golden eagles and Red-tail hawks nest here while the Cooper's hawk and Northern Goshawk only migrate through. Even bald eagles are a common resident of the Badlands. The burrowing owl (Athene cunicularia), shown here, looks for a meal while standing in a prairie dog village.
The pronghorn (Antilocapra Americana) are a common resident of the Badlands. Herds of these graceful grazers are well suited for life in the vast grasslands of the Badlands. With little cover from prey, the pronghorn's ability to run upwards of 50 mph (80 kph) for a long distance aids in its ability to survive.
Most people today see the White River Badlands by visiting Badlands National Park. The park offers over 50 miles (80 kilometers) of paved and good gravel roads that pass by the most scenic views and close to the free ranging wildlife. Primitive camping is available, as are miles of hiking and biking trails. The Oglala Lakota Nations co-manage 50 percent of the Badlands National Park with the National Park Service. One of the world's rarest mammals, the black-footed ferret (Mustela nigripes) was reintroduced here in 1994 and is prospering well in the grassland wilderness. [Top 10 Most Visited National Parks]
Erosion in the Badlands is constant and ongoing. Every time a thunderstorm unleashes a torrent of rain, soil is washed from the hills, pinnacles and buttes. It is estimated that 1 inch (2.5 centimeters) of rock is eroded each year by the rains and howling winds. At this rate, the Badlands of South Dakota will be completely leveled in another 500,000 years a very short period of geological time.
The serrated Badlands landscape was slightly faulted and warped during the mountain building forces that formed the Black Hills some 70 miles (113 km) to the west. Together with the constant and continual forces of erosion, the rich fossil beds that lay buried for millions of years were again brought to the surface and exposed. The layers of ancient sedimentary rock of the White River Badlands have become a scientific treasure and modern day calendar of geological history and time. [Image Gallery: Dinosaur Fossils]