North Dakota Geology

Geology and Time

• Geology and time are closely related, with layers of sediment capturing changes in climate, water levels, and life over billions of years.
• These changes shaped North Dakota's modern landscape and economy.

Divisions of Geological Time

• Geological time is divided into eras, periods, and epochs, with eras being the largest periods.
• Eras are made up of several periods, which are subdivided into epochs.
• Epochs are made up of formations, which are measured by layers of rock buried deep under the surface.

Eras and Stratigraphic Columns

• There are four eras characterized by geological changes brought about by wind, water, earthquakes, or volcanoes, and the development of plant and animal life.
• Stratigraphic columns show the eras and cover the Earth's history, including North Dakota's 600 million-year history.

North Dakota's Geological Record

• The Paleozoic Era began about 570 million years ago, with seas flowing and draining, forming the Williston Basin.
• Life expanded, evolved, and became extinct during this era.
• The Mesozoic Era and Cenozoic Era saw the dominance of mammals and grasses, with climate changes leading to the current pattern of cold winters and warm summers.

Paleontological Research

• Geologists and paleontologists read the layers to learn about the landscape and non-human life forms.
• Knowledge is based on 200 years of scientific research and is continually evolving with new discoveries.

Special Terms

• BPE (Before the Present Era) is used to denote time before the present, especially for events that occurred millions of years ago.
• Core samples are cylindrical slices of Earth's layers obtained by drilling below the surface.
• Coteau refers to an area east of the Missouri River characterized by small lakes and ponds formed by glaciers.
• Dinosaurs were extinct reptiles from the Mesozoic Era, some walking upright on two legs and others on four.
• Erratics are large rocks left on North Dakota prairies by glaciers, too heavy to be moved by water or wind.
• Esker refers to a ridge formed by gravel and sand deposited by streams flowing under or through glaciers.
• Extinction refers to the complete disappearance of a species from Earth, either globally or in a specific region.
• Formation refers to a distinct layer of rock visible in cliffs or river banks, named after nearby permanent features.
• Geologist refers to a scientist who studies Earth's rocks, minerals, and geological processes.
• Glacier refers to a large mass of ice formed from compacted snow that moves slowly and reshapes the land underneath it.
• Glacial till refers to sediment left behind as glaciers retreat, varying in size from clay particles to boulders.
• Iridium is a rare mineral found abundantly in asteroids and meteors, associated with the K-T boundary layer linked to dinosaur extinction.
• K-T Boundary refers to the geological boundary marking the end of the Cretaceous Period and the start of the Tertiary Period, associated with mass extinctions, including dinosaurs.
• Lake Agassiz refers to a large freshwater lake formed during the Ice Age, leaving behind sediment that shaped the Red River valley.
• Lignite refers to a type of coal found in North Dakota, lower in heat production compared to other types of coal.
• Mammals refer to animals that give birth to live young and nurse them with milk until they can feed themselves.
• Moraine refers to a hill of gravel or rock deposited by a melting glacier.
• Paleontologist refers to a scientist who studies fossilized plants and animals from ancient times.
• Sediment refers to material deposited by wind, water, or ice.
• Sedimentary rock refers to rock formed from compressed layers of sediment over geological time.
• Strata refer to layers of sediment or rock beneath Earth's surface.
• Stratigraphy refers to the study and visualization of geological layers and their relationships.

Formations

• Formations are layers of sand, silt, rock, and other substances laid down in North Dakota over millions of years.
• Each layer has a name, which represents a time period, and its own story, including origins, conditions, and contents.
• Stratigraphic charts are used to view the orders of stratigraphy.

The Williston Basin

• The Williston Basin is a geographical area covering parts of Saskatchewan, Manitoba, Montana, South Dakota, and North Dakota.
• The basin is characterized by sedimentary layers, with a depth of over 16,000 feet near the center.
• The area is a major source of coal, oil, and natural gas.

Petroleum Formation

• Petroleum formation occurred when plankton and microscopic organisms in inland seas died and fell to the sea floor.
• The organisms were covered by sediments over millions of years, creating pressure and heat, and transforming into oil and gas.

The Missouri and the Red River

• North Dakota's rivers are youthful in geological terms, with shallow river beds prone to flooding.
• Historical flow directions include the pre-glaciation path of the Missouri River and the current flow of the Red River.
• The Missouri River's path was changed by glaciers, which redirected the river southward.

Glaciation Events

• Glaciation events refer to periods when ice advanced from polar caps to usually warmer lands.
• The last ice age occurred from 2.6 million years ago, with multiple glaciation periods during the Pleistocene Epoch.
• Glaciers were thousands of feet thick, composed of half ice and half debris.
• Debris included rocks, gravel, and sand carried and deposited by glaciers, forming glacial till.

Types of Glacial Deposits

• Erratics refer to individual rocks left behind by glaciers.
• Moraines refer to hills of sand, gravel, and rocks left by glaciers.
• Eskers refer to ridges formed by sediment carried beneath glaciers' meltwater rivers.

Last Ice Age in North Dakota

• The last ice age in North Dakota occurred from 25,000 to 12,000 years ago, with ice sheets up to 400 feet thick covering three-fourths of the state.
• The glaciers created rolling hills and formed Glacial Lake Agassiz, which covered 110,000 square miles.

Plants and Animals

• Early geological history: North Dakota was submerged under water with tiny one-celled aquatic plants.
• Tropical plants like palm trees, giant redwoods, and ferns formed dense forests during warm periods.
• The transition to grasslands occurred due to semi-arid climate and grazing animals.
• Geological epochs and plant evolution: the Late Cretaceous Period, Eocene Epoch, Oligocene Epoch, and Miocene Epoch saw the evolution of different plant species.
• Fossil record and grassland formation: the Miocene Epoch saw the debate among scientists about the origin of North Dakota's grasslands.
• Post-glacial changes: the climate became drier, leading to the spread of modern grasses like Big Bluestem and prairie flowers.

Soil

• Formation of soil: soil develops from rocks over millions of years, influenced by weathering and plant roots.
• Components of soil: soil is a mixture of sand, silt, and clay, with organic matter making up 5% of soil.
• Effect of climate on soil: climate influences plant growth, which in turn impacts soil composition.
• Characteristics of grassland soil: grasses contribute more nutrients back to the soil, enhancing fertility.
• Soil horizons: soil scientists study soil horizons to understand soil characteristics and fertility.

Animals

• Ancient fauna and evolution: North Dakota hosted diverse microscopic organisms in warm seas, and vertebrates with backbones evolved, including dinosaurs, lizards, and mammals.

• The impact of the K-T boundary: the asteroid impact theory explains the mass extinction at the K-T boundary, but ongoing research considers other factors.

• Animals of the Late Cretaceous Period: marine life included small creatures like clams, corals, urchins, and lobsters, and larger predators like the Plioplatecarpus or mosasaur, and the flightless bird Hesperornis regalis.### Dinosaurs and Flying Reptiles

• Massive carnivore, Tyrannosaurus rex, up to 40 feet long and 20 feet tall, with a five-foot-long head and immense bite force.

• Known predator of Edmontosaurs and Triceratops, debated as a predator or scavenger.

• Flying reptiles like Pteranodon inhabited the skies, with a wingspan of 20 feet, primarily feeding on fish.

Impact of the K-T Boundary

• Extinction event around 65 million years ago marked the end of dinosaurs and dominance of reptiles.
• The rise of mammals followed, shaping the future fauna diversity.

Eocene Epoch (55 to 34 million years ago)

• North Dakota experienced tropical conditions with dense forests.
• Diverse fauna included:
  • Coryphodon: Hippopotamus-like, swamp-dwelling mammal.
  • Eohippus (Hyracotherium): Early horse ancestor, small with multiple toes.
• Global cooling marked the end of the Eocene Epoch.

Oligocene Epoch (33 to 23 million years ago)

• North Dakota transitioned into a treeless plain with shrubs and grasses.
• Major fauna included:
  • Thunder Beast (Brontops): Large, intimidating plant-eater with bony snout projections.
  • Mesohippus: Descendant of Eohippus, larger than its predecessor, adapted to browsing leaves.
  • Poebrotherium: Early camel ancestor, lacked humps, similar in size to a goat.
  • Leptomeryx: Small, antler-less, fast-running deer-like animal.
  • Saber-toothed cats (Dinictus): Predatory with long, serrated canine teeth.
  • Rabbits (Palaeolagus), tortoises (Stylemys), sweat bees (Celliforma species), and rodents (Eumys species) were also common.

Animals of the Pleistocene Epoch

• Woolly Mammoths (Mammuthus primigenius)
  • Originated from Asia via the Bering Land Bridge.
  • Reached up to nine feet at the shoulder.
  • Ate grass, roots, and tree bark using their tusks and trunk.
  • Had heavy, dark brown coats with a fine undercoat for warmth.
  • Became extinct about 10,000 years ago, coinciding with human presence in North Dakota.
• Mastodons (Mammut americanum)
  • Evolved in North America over millions of years.
  • About 10 feet tall at the shoulder.
  • Used tusks to tear bark from trees; preferred browsing leaves and bark.
  • Had long, dark, thick hair coats with a fine undercoat.
  • Lived in boggy areas and became extinct about 10,000 years ago.
• Bison latifrons
  • Ancestor of modern bison, larger than today's species.
  • Had horns measuring seven feet from tip to tip.
  • Lived in small herds and preferred woodland habitats.
• Ice Age Horses (Equus)
  • Resembled modern horses with a single toe and hard hoof.
  • Larger than their ancestors; grazers dependent on grass.
  • Became extinct in North Dakota and North America by the end of the Ice Age.
• Saber-Toothed Cat (Smilodon fatalis)
  • Fearsome predator, slightly smaller than a modern lion but heavier.
  • Had powerful front legs and seven-inch-long canine teeth.
  • Used strong jaws to bite into prey's skull, sometimes breaking their canines.
  • Extinct by the end of the Ice Age.

Extinction and Causes

• Larger Ice Age mammals like mastodons and horses became extinct.
• Smaller to medium-sized animals like deer survived.
• Factors contributing to extinction may include climate change and human hunting.

The Paleontology Laboratory

• Role of Paleontologists
  • Study fossils to reconstruct ancient ecosystems and understand evolutionary history.
  • Carefully document fossil locations and geological layers to date and contextualize fossils.
  • Protect fragile fossils with plaster jackets during excavation to preserve their integrity.
• North Dakota's Paleontology Laboratory
  • Housed within the State Historical Society, it holds thousands of fossil specimens.
  • Fossils include bones, teeth, and fossilized plants captured in rock formations.
  • The laboratory is essential for cleaning, identifying, and cataloging fossils.
• Excavation and Preservation
  • Fossils are excavated from rock formations and meticulously cleaned in the laboratory.
  • Analyze bones for identifying features like spinal processes and tooth structures.
  • Fragile fossils may require reconstruction or replication for display to protect the originals.
• Common Fossil Finds in North Dakota
  • Edmontosaurus and Triceratops fossils are relatively common.
  • Tyrannosaurus rex remains are rarer due to fewer discoveries.
  • Fossils from the Oligocene Epoch are scarcer due to high erosion rates.
• Displaying Fossils
  • Fragile or incomplete fossils are reconstructed or replicated for museum displays.
  • Techniques include sculpting missing parts, creating molds, or crafting replicas from lightweight materials.
  • Original fossils are preserved while replicas are used for educational and exhibition purposes.

This quiz covers various geologic aspects of North Dakota, including formations, epochs, and geological events. Test your knowledge of the state's geological history!