Exam 4 - Historical Geology 1404

Formation of Iceland

Formed about 16-17 million years ago from surface volcanism.

Pleistocene glacial thickness

Glaciers during this epoch reached thicknesses of up to 3 kilometers.

Till

Glacial debris deposited directly by the ice.

Moraines

Large glacial hills that can be terminal or lateral.

Outwash plains

channels, deltas, and debris formed from the

draining glacial melt

Ice-scoured plains

fjords, u-shaped valleys, stripped and striated

bedrock

Deep sea stratigraphy indicator

Planktic foraminifera data used to record fluctuations in sea climate. One problem- although the forams record a detailed record of SEA climate, the

terrestrial data doesn't match it all the well

Trigger for Antarctic glaciation

40mya - Triggered by separation of

Antarctica from other

continents and its centering

on the South Pole

Pleistocene temperature variation

Global temperatures varied by as much as 10°C over 20 warm-cold episodes.

Potential sea level rise

If all modern glacial ice melted, sea levels would rise about 70 meters.

Isostatic rebound

The gradual rising of land after the weight of a glacier melts away.

Pluvial lakes

large lakes in arid environments that were supported by the cooler weather and heightened precipitation levels associated with glacial periods (ex: Death Valley).

Proglacial lakes

Lakes formed along the margins of melting glaciers. (ex: Great Lakes).

Varves

Sedimentary deposits that provide evidence of both pluvial and proglacial lakes.

Milankovitch Cycles

Cause of Glaciation - Orbital variations (eccentricity, obliquity, precession) that influence glaciation cycles.

Albedo effect on glaciers

Cause of Glaciation - Growing glaciers reflect more sunlight, lowering global temperatures and encouraging more growth.

Modern glacial coverage

Glaciers currently cover about 10% of the Earth's surface.

Primary glacial mineral resource

Sand and gravel, which are finite and highly sought after.

Isthmus of Panama

forms about 3 mya, Separated the Atlantic from the Pacific and created a permanent land bridge between North and South America

Cenozoic Era timeframe

66 million years ago to the recent epoch.

Three periods of the Cenozoic

Paleogene (Oldest) , Neogene, and Quaternary (Youngest).

Cenozoic Plate Tectonics

The Cenozoic is largely dominated by the ongoing fragmentation

of Pangaea.

North and South America continue to move westward, overriding the

Pacific plate and opening the Atlantic basin

India continues moving north, crashing into Asia

Africa continues north, colliding with Europe

Australia moves northward away from Antarctica

Two major Cenozoic orogenic belts

Alpine-Himalayan and Circum-Pacific.

Alpine Orogeny cause

Africa moving north, closing the Tethys, and colliding with Europe.

Himalayan Orogeny cause

The collision of the Indian plate with Asia.

Circum-Pacific belt cause

Subduction of the Pacific plate under surrounding continents.

Most dangerous volcano in the Cascade Range

Mount Rainier.

Laramide Orogeny timing and style

Late Cretaceous to Eocene, characterized mostly by vertical uplifts.

San Andreas Fault origin

Formed 30 million years ago after the subduction of the Farallon plate.

Colorado Plateau uplift

Elevated area of Colorado, Utah,

Arizona, and New Mexico

Uplifted in the Neogene from sea level up to 1,800 meters.

Basin and Range Province tectonic style

Crust was stretched and thinned, creating normal faults and valleys.

Possibly a failed rifting event of the

North American Craton or the shallow

angle of the Farallon plate subduction

Snake River Plain age progression

Older southwest, younger northeast, indicating a mantle plume under Yellowstone.

Rio Grande Rift

North-South failed rift zone extending from Colorado to Mexico.

Cretaceous seaway over the Continental Interior

Zuni Epeiric Seaway (Western Interior Seaway), which drained by the Paleogene.

Appalachian Mountain rejuvenation cause

Isostatic rebound after the mountains eroded into a rolling plain.

Water gap vs. Wind gap

Water gaps still have active streams; wind gaps no longer have flowing water.

Tejas sea

Brief Cenozoic marine inundation over the Gulf Coast region.

Post-extinction reef builders after rudist

Scleractinian corals, which took over reef-building niches after rudist reefs went extinct.

Cenozoic gymnosperm distribution

Pushed into fringe environments like high altitudes and the extreme north by angiosperms.

Evolution of grasses

First became important 40 mya; heat-tolerant C4 grasses appeared 6 mya.

Cenozoic Birds - Avian Dinosaur skeleton stability

Unchanged since the Cretaceous because flight adaptation limits structural design tweaks.

Monotremes

Egg-laying mammals that lack nipples and 'sweat' milk; includes platypus and echidna.

Marsupials

Pouched mammals giving birth to immature young; Australian species show convergent evolution (ex: Kangaroos)

Placental mammals

Mammals giving birth to mature live young, comprising over 90% of modern mammals.

Titanoboa

The largest terrestrial predator of the Paleocene epoch, living 60-58 mya (Snake creature)

Enteledont

Nicknamed the 'Hell pig' but actually more closely related to whales and hippos.

Oldest bat fossil

Eocene-age fossil found in the Green River formation of Wyoming.

The ONLY flying mammals!

Artiodactyls vs. Perissodactyls

Artiodactyls are even-toed with complex stomachs; perissodactyls are odd-toed with simple stomachs.

Whale evolutionary ancestor

Evolved from land-dwelling artiodactyls like Pakicetus, sharing an involucrum and astragalus bone.

Pleistocene extinction hypotheses

Climate Change (rapid vegetation shifts) and Overkill (human hunting of slow megafauna).

Great American Interchange

Land bridge connection 3 mya allowing animal migration between North and South America.

Connection allows for the flow of animals north and south

• Leads to mass die off of South American predators and herbivores

Hominids vs. Hominins

Hominids include all great apes; hominins include only modern humans and extinct bipedal ancestors.

Primate evolutionary trends

Tree-dwelling traits, stereoscopic vision, grasping hands with opposable thumbs, and fewer, less specialized teeth.

Prosimians

The oldest primate lineage, including lemurs, lorises, galagos, tarsiers, and tree shrews.

Old World Monkeys traits

Close-set, downward-facing nostrils, grasping hands, and non-prehensile tails; found in Africa and Asia.

New World Monkeys traits

Flat faces, widely separated nostrils, and prehensile tails; found in Central and South America.

Hominoids distinguishing trait

Highly flexible shoulders and a complete lack of tails.

First Hominoid

Aegyptopithecus, dating to the Eocene epoch (56-33 million years ago).

Dryopithecines vs. Sivapithecids

Dryopithecines are ancestors of gorillas, chimps, and humans; Sivapithecids led to modern orangutans.

Sahelanthropus tchadensis

7-million-year-old hominin. Occurs at or near the time that human and

chimpanzee ancestors diverged

Ardipithecus traits

Lived 5.8-4.4 mya; possessed dexterous hands and opposable big toes but inflexible feet.

A. anamensis

The oldest known Australopithecine (4.2 mya), which was bipedal with primitive dentition.

A. afarensis (Lucy)

Fully bipedal hominin (3.9-3.0 mya) with a slightly larger brain than a chimp.

A.africanus

3.0-2.3 mya. Flatter faced

Slightly larger brain

Not as well-suited for being bipedal

Footprint Tuff

3.8-3.4 million-year-old fossil footprints showing bipedal hominins walking on the balls of their heels.

Robust Australopithecines

Genus Paranthropus (A. robustus and A. boisei); specialized vegetarian lineage with smaller, chimp-like builds.

Homo habilis

Lived 2.5-1.6 mya; evolved from Australopithecines, possessing a 700 cc brain and long arms.

Homo erectus

First hominin to leave Africa; possessed a 1,300 cc brain, made tools, and used fire.

H. heidelbergensis

Archaic human species that served as the direct ancestor of Neanderthals and modern humans.

Neanderthals

Hominins with low, heavy brow ridges, muscular bodies, and brains slightly larger than modern humans.

Denisovans

Only known from a few fossils (finger bone,

teeth and DNA)

Existed alongside Neanderthals

Cro-Magnons

Early Homo sapiens (35,000-10,000 years ago) known for cave paintings and specialized tools.

Why only one human species remains

Likely due to climate stress, competition, low population sizes, and cultural/technological advantages of H. sapiens.

Anthropocene

Proposed geological epoch recognizing significant human impact on Earth's ecosystems and geology.

Anthropogenic

Originating in human activity, particularly regarding climate change and pollution.

Stratigraphic markers

Physical, chemical, or biological indicators in rock layers used to define geological epochs.

Radionuclide fallout

Mid-20th century atomic test marker proposed to define the start of the Anthropocene.

Technofossils

Man-made materials like plastics, concrete, and aluminum that will remain in the rock record.

Mass extinction threshold

A geologically rapid interval during which at least 75% of known species go extinct.

Background extinction rate

The normal rate of extinction, estimated at about 1 species per 1-2 million species yearly.

Modern vertebrate extinction rate

Observed modern extinction rates are dozens to 100 times higher than background rates.

North American bird decline

Over 1 in 4 birds (nearly 3 billion) have disappeared since 1970.

Modern insect decline

Over 40% of insect species are declining, with total mass falling by 2.5% annually.

Modern analogues

Using modern ecosystems and organisms to infer the behavior and environments of ancient ecosystems.

PETM (Paleocene-Eocene Thermal Maximum)

A rapid global warming event 55.8 mya with a 5-8°C temperature rise.

Primary cause of the PETM

A combination of intense volcanism and the mass release of methane clathrates.

Methane clathrates

Frozen methane bubbles trapped in ice that release greenhouse gases when warmed.

PETM ocean extinction

Extinction of 35-50% of deep-sea benthic foraminifera due to acidification and anoxia.

PETM terrestrial mammalian response

Northward migration of mammals and rapid radiation of Artiodactyla, horses, and primates.

Bighorn Basin leaf fossils

Fossil leaves from Wyoming showing a distinct shift to warm, humid PETM climates.

PETM relevance today

Serves as a historical analogue, though modern CO₂ levels are rising much faster.

Multiple Choice: As Africa collides with Europe this begins the ___________ orogeny.

Circum-Pacific

African-European

Alpine-Himalayan

Antler

Alpine-Himalayan

Multiple Choice: The Cenozoic Era is part of the ____________ Eon.

Paleozoic

Precambrian

Cambrian

Phanerozoic

Phanerozoic

Multiple Choice: The modern Appalachians exist because of this process:

Isostatic rebound

Transform plate boundaries

Convergent plate boundaries

Divergent plate boundaries

Isostatic rebound

Multiple Choice: The Andes Mountains are a volcanic mountain range located __________________.

On the west coast of North America

On the west coast of South America

The west coast of Africa

The west coast of Canada

On the west coast of South America

Multiple Choice: Cenozoic-aged sediments in the continental interior of North America were mostly derived from:

The Black Hills

The Colorado Rockies

The Yellowstone Supervolcano

The Grand Canyon

The Black Hills

Multiple Choice: Which of these were NOT formed as a result of the Laramide Orogeny?

The Appalachians

The Black Hills of South Dakota

The Grand Canyon

The Colorado Rockies

The Appalachians

Multiple Choice: Mt Saint Helens, Mt Ranier, and others are part of the:

Andes

Himalayas

Alps

Cascade Range

Cascade Range

True or False:

The Himalayans are very volcanically active due to the subduction zone created by the collision between the Indian and Asian plates.

False

Multiple Choice: The only Sloss sequence (major transgression) to occur in the Cenozoic:

Absaroka

Zuni

Sauk

Tejas

Tejas