Makoshika State Park derives its name from a Lakota phrase, Maco sica, which means "land of bad spirits", or "bad lands."    Makoshika sits on the northern terminus of the Cedar Creek Anticline, an uplifting of the earth that resembles a ripple in a blanket.  Because the park is situated on an anticline, the sediments exposed in the park are older than the sediments seen in the badlands of North and South Dakota, and erosion of the sediments exposes a wealth of dinosaur fossils. 
    The Cedar Creek Anticline is approximately 30 miles wide and 150 miles long, and trends southeasterly from Glendive into the northwestern corner of South Dakota.  Travel south of Glendive along the anticline and you ascend higher on the anticline, allowing you to access sediment layers from the time before dinosaurs roamed North America, when an inland sea covered much of the interior of North America. The shallow, warm and salty inland sea, known as the Niobrara or Western Interior Seaway, extended from Canada to Mexico and from the Dakotas to what would become the Rocky Mountains, and drained both into Canada and the Gulf of Mexico.
    During the Cretaceous Period, 135 -- 65 million years ago, the inland sea began to slowly recede as the continent of North America became firmer.  The continent had drifted to its current position on the planet and made contact with the oceanic plates.  That contact contributed to the buckling and rising of mountain ranges and allowed the inland sea to slowly drain from the continent's interior.     
    Three times during the Cretaceous Period, the inland sea advanced to its greatest extent and then receded.  The land exposed during those recessions has been described as sub-tropical lowland swamps.  Throughout those swamps, broad river plains deposited silt and coarser sediments across the area.  Large, broadleaf plants and lush undergrowth provided plenty of food for the large herbivore (plant-eating) dinosaurs, and close by those large herbivores were the carnivorous (meat-eating) dinosaurs, such as Tyrannosaurus rex.  
    The sediments that make up the park as a result of millions of years of deposition are referred to as formations.  The grayish clays and shales of the Hell Creek Formation contain dinosaur fossils from the Cretaceous Period of 135 -- 65 million years ago (often called the Age of Reptiles), and the sediments and fossils of the last 2 million years of the Cretaceous Period make up the lower sediment deposits in the park.  Ten different species of dinosaurs have been found in Makoshika; most common are the large herbivores of the late Cretaceous Period, such as Triceratops and Hadrosaurus and the large carnivores like  Tyrannosaurus rex.  In 1997, a very rare and complete skeleton of a Buganosaura was discovered in the park.  Buganosaurs were bipedal herbivores 10-13 feet in length and weighed up to 500 pounds.  In addition to dinosaur fossils, remains of ancient fish, turtles, and crocodiles that lived in the water of the ancient inland sea of the Cretaceous Period are found in areas of the park.
    The Fort Union Formation, often called the Age of Mammals, is a series of sediments laid down on top of the Hell Creek Formation during the Tertiary Period, 65 -- 2 million years ago, and can recognized as the upper 100 feet of tan sediment layers along the tops of the higher ridges in the park.  The Fort Union Formation contains the fossils of early mammals which rose into predominance following the mass extinction of the dinosaurs 65 million years ago.  With the extinction of dinosaurs, competition was removed for the small, early mammals that began arising near the end of the age of reptiles.  
    The boundary between the Hell Creek and Fort Union Formations is called the KT Boundary (KT stands for "Cretaceous-Tertiary," the two periods of time separated by the boundary).  The KT Boundary represents the point in time when dinosaurs went extinct and mammals rose to predominance.  Below the KT Boundary is evidence of dinosaur fossils and the plant life of their time;  above the boundary there are no dinosaur fossils, but plenty of fossil evidence of small mammals and the plant life of their time.
    There are two competing theories about why dinosaurs went extinct.  The Gradual Die-Out theory holds that there was a gradual change in the Earth's climate and the great amounts of food that plant-eating dinosaurs needed was becoming harder to find; eventually, with little food left, the dinosaurs died off in great numbers.  
    The second theory, the Sudden Die-Off, holds that a giant asteroid collided with Earth, which instantly killed a great deal of the plant and animal life on North America and created conditions which would kill off even more within a couple of years.  Indeed, evidence shows that an asteroid did impact Earth 65 million years ago in the Gulf of Mexico near the Yucatan Peninsula.  By studying the impact crater in the ocean's floor, scientists estimate the asteroid to have been 120 miles in diameter, and struck the earth at a 30 degree angle while traveling at a speed of 10 miles per second.  The collision caused a great cloud of ash and dust to block the sun for several years, and the lack of sunlight caused most of the planet's plant life to die, removing the great amounts of food the plant-eating dinosaurs depended upon.  Soon after, the meat-eating dinosaurs were out of food, as well.  The asteroid impact killed off 90% of all plant life and 70% of all animal life, either instantly by the impact or from the disruption of the food chain caused by the ash cloud blocking the sun.
    Several pieces of evidence appear at the KT Boundary to suggest that there was an asteroid collision 65 million years ago, and that it at least caused the extinction of what dinosaurs remained, if not all of a healthy population.  First, there are numerous dinosaur fossils below the boundary, and only a few meat-eating dinosaur fossils found above the boundary as meat-eating dinosaurs scavenged the remains of the plant-eating dinosaurs.  Second, below the boundary are only small, nocturnal mammals; above the boundary, mammal fossils are numerous and indicate a sudden rise in numbers of species and diversity.  Third, what is referred to as the Fern Spike is found at the boundary.  All the plants found during the time of dinosaurs disappeared at 65 million years ago, and a whole new group of plants appeared, including a large number, or "spike," of ferns. 
    Other evidence supports the theory that an asteroid collided with Earth 65 million years ago near the Yucatan Peninsula.  Shock Quartz is found at the KT boundary, and shock quartz is only formed when quartz is subjected to sudden, high temperatures.  Further, there is evidence of an Iridium Splash.  Iridium is an element that is rare on Earth but very common in asteroids.  An iridium splash is found all across the width of North America and is thicker in the southern states near the Gulf of Mexico and thinner in the northern states like Montana.  Much like if you threw a rock into a mud puddle, the mud splash would be thicker where the rock entered the water and much thinner further away from the point of impact.  The iridium splash found at the KT Boundary suggests that the asteroid impact really did occur 65 million years ago, and was a large enough impact that the resulting ash and dust cloud could have blocked out the sun long enough to kill off all plant life.
    Much more recent geologic activity in the area has allowed much of the sediment layers of the Hell Creek and Fort Union Formations to erode, providing the beautiful badlands topography we see today,  and exposing the fossils of more than 100 million years of plant and animal life.  One of the processes that contributed to the way the park looks today is the uplifting that occurred with the Cedar Creek Anticline.  Immense grassland fires also contributed to the erosion of the area by removing much of the plant life that held the surface soil in place.  
    Evidence of human existence in eastern Montana dates back to 12,000 years ago, and evidence of their activity in the Makoshika area is continually studied.  A well-renowned archeological site -- the Hagan Site -- is located in Glendive on the Yellowstone River a couple of miles from the park.  Evidence found in the fire pits of that site indicate that early humans returned to that site year after year, perhaps as part of an annual hunting migration or perhaps as part of a ritualistic practice.  Stone points and other evidence are often found in Makoshika from that same time period.
    Today, Makoshika's highly eroded badlands topography provides unique, challenging recreational opportunities, and provides a glimpse into the distant past, when dinosaurs ruled the earth and small mammals waited for their time to prosper.