Geology Final Exam Ch. 15

Neogene Period

- Divided into two epochs: Pliocene, & Miocene (oldest)

The Cenozoic Era

-65.5 million years ago to the present -Name "Cenozoic" = "new life" or "recent life" -The Cenozoic Era followed a mass extinction of the dinosaurs and many other organisms -Cenozoic rocks contain modern types of plants and animals, more advanced than those of Paleozoic and Mesozoic. -Adaptive radiation of the mammals -Cooling of the Earth's climate resulting in the Ice Ages -Evolution of humans

The Great Salt Lake

Small remnant of Pleistocene Lake Bonneville

Formation of Long Island, NY

Terminal moraine

Formation of the Great Lakes

Depressions scoured by glaciers and flanked by moraines

Position of the continents during Eocene (about 50 m.y. ago)

-Antarctica and Australia are still connected -India has not yet collided with Asia -North and South America are not yet connected -South America is connected or nearly connected with Antarctica

As a result of the Ice Age 1:

-Climatic zones in the Northern Hemisphere were shifted southward. -Arctic conditions prevailed across Europe and the U.S. -Sea level dropped as much as 75 m (225 ft) and the shoreline shifted seaward, exposing the continental shelves as dry land.

Closure of the Tethys Sea

-Collision of Africa and India with Eurasia, forming the Alps and Himalayas. -Tethys Sea deposits were deformed into mountain ranges

Paleogene Period

-Divided into three epochs: Oligocene (youngest), Eocene, & Paleocene (oldest)

Paleogeography and Plate Tectonics

-During Cenozoic, the Atlantic and Indian Oceans widened, and the continents moved to their current positions. -Half of the present ocean crust has formed at the mid-ocean ridges since the beginning of Cenozoic.

As a result of the Ice Age 4:

-Formation of the Great Lakes -Formation of Cape Cod, MA -Formation of Long Island, NY -Formation of Niagara Falls -Formation of large ice-dammed lakes, including Lake Missoula -Formation of hummocky topography and Pleistocene sand dunes

Tectonic and Paleographic Changes and Their Effects on Climate

-Glaciation led to regressions. -Continental interiors were not flooded by epicontinental seas during Cenozoic. -Marine transgressions were limited. -Overall cooling trend during Cenozoic.

Rocky Mountains and High Plains

-Late Eocene and Oligocene volcanic activity in Yellowstone National Park area. -White River Formation contains well-preserved skeletons of Oligocene mammals. Also makes up the Badlands of South Dakota. -Well preserved fossil insects and leaves are found at Florissant Fossil Beds National Monument in Colorado. They were buried when Oligocene volcanic ash settled into a lake. -Volcanic activity occurred during Miocene in the central and southern Rockies. -Gold deposits at Cripple Creek, Colorado formed in association with a Miocene volcano. -Regional uplift of Rockies began in Miocene.

Volcanoes of the Cascade Range

-Mt. St. Helens -Mt. Rainier -Mt. Adams -Mt. Hood -Mt. Jefferson -Mt. Lassen -Mt. Shasta

Columbia Plateau

-Named for the Columbia River, between Washington and Oregon -Built by volcanic activity -West of the Columbia Plateau, more viscous lava produced the volcanoes of the Cascade Range. -Volcanism is caused by the North American plate overriding the Juan de Fuca plate in the eastern Pacific.

Active volcanism

-New Mexico, Arizona, Idaho -Mexico -Iceland -Pacific rim

Important Continental Breakups

-North Atlantic rift separated Greenland from Scandinavia -Australia separated from Antarctica. Circumpolar currents isolated Antarctica from warmer waters. Led to cooling of Antarctica. -Cold, dense ocean waters around Antarctica drifted northward along ocean floor, contributing to global cooling and the Ice Age. -Rifting occurred between Africa and Arabia, forming the Red Sea and the Gulf of Aden.

Pleistocene Ice Age

-Pleistocene is significant as the time in which humans evolved. -More than 40 million km3 of snow and ice covered about 1/3 of Earth's land area. -Continental glaciers covered much of North America and Europe.

Basaltic lava

-Poured out of deep fissures and buried more than 500,000 km2 of land in Washington, Oregon, and parts of Idaho during Miocene, about 15 m.y. ago -Lava flows are more than 1.5 miles thick

Basin & Range Province

-Resulted from stretching of earths crust -Up-arched during mesozoic -Erosion of fault blocks followed by volcano clogged rivers & made lakes develop behind debris dams -Gypsum salt layers formed when lakes evaporated

As a result of the Ice Age 2:

-Streams cut deep canyons into the continental shelves and on land. -Land bridges existed and led to migrations of mammals, including humans -The land was sculpted by glaciers in Europe and North America. -U-shaped valleys formed in mountainous areas -Rainfall increased at lower latitudes. -Large lakes formed in the Basin and Range Province.

Crustal uplift

-Tetons of Wyoming -Sierra Nevada -Central and northern -Rockies -Alps -Himalayas

Colorado Plateau Uplift

-The best-known feature in the Colorado Plateau is the Grand Canyon. -Eroded by the Colorado River to a depth of more than 1.6 miles. -The river eroded through Phanerozoic strata and into the Precambrian basement rocks. -The rocks are relatively flat-lying. They were not deformed during Mesozoic orogenies. -The Colorado Plateau has been subject to uplift and erosion. Uplift occurred during Pliocene. -Faults formed locally, providing conduits for volcanic rocks. -Ex. San Francisco Peaks near Flagstaff AZ.

Lake Bonneville

In Utah covered more than 50,000 km2 and was about 1000 ft deep in places.

Antarctica during Paleogene

-The climate was semitropical and mild in Antarctica during Paleogene, as indicated by fossil spores and pollen, despite the fact that it sat on the South Pole. -Before Antarctica separated from Australia, it was warmed by currents moving southward from more equatorial latitudes. -Australia began to separate from Antarctica during early Eocene, about 55 m.y. ago. -After separation, circumpolar currents developed around Antarctica, cutting it off from equatorial currents. -This resulted in temperature decrease and glacial conditions over Antarctica.

Global Surface Cooling

-There was a 10o C (18o F) temperature drop at end of Cretaceous Period. -Several warming trends occurred during late Paleocene and Eocene

As a result of the Ice Age 5:

-Weight of the ice depressed the continental crust to as much as 200-300 m downward. -Uplift (isostatic rebound) after ice melted. Coastal features are now elevated high above sea level.

Basin & Range Province Hypothesis

-West moving NA overrode spreading center & uplifts stretched crust -Normal faulting replaced subduction -Extensions & uplift, ocean slab pressed upward against overlying crust causing tensional faulting

As a result of the Ice Age 3:

-Winds coming off glaciers blew sediment southward forming löess deposits (Missouri River area, central Europe, northern China) -Parts of northern and eastern Africa that are currently arid had abundant water and were fertile and populated by nomadic tribes. -Nomadic tribes hunted along the edges of the continental glaciers. Wild game was abundant, furs provided warm clothing, and there were less problems with spoiled meat in the cold temperatures.

Periods of Cenozoic

-Youngest: Quaternary Period -Younger: Neogene Period -Older: Paleogene Period

Reasons class is useless

Because it doesn't matter how the earth got to how it is. We live here. Get over it

Tectonic Change During Cenozoic

Compressional style of "collision-subduction-thrust faulting" replaced by lateral movement of American and Pacific plates grinding past each other

Quaternary Period

Divided into two epochs: Holocene (the current epoch), & Pleistocene

The Bonneville salt flats

Formed as the lake evaporated

Elongate Mountain Range

Formed by up-faulted blocks along N-S trend, supplied erosional detritus to down-faulted basins between up-faulted blocks

Lake Missoula

Large ice-dammed lakes, drained catastrophically, forming the channeled scablands

Milankovitch Cycle

Repeated advance and retreat of glaciers

San Andreas Fault System

The western edge of the North American plate came into contact with the northwestward-moving Pacific Plate, forming the San Andreas Fault system