GLG exam 3

What are glaciers and how do they form and move? What are the different types of moraines and how do they form?

Glacier--mass of ice formed on land from snow that survives from year to year and creeps down slope or outward due to the stress of its own weight (recrystallization / compression)

Form + Mvmnt-- due to gravity . top is fracturing, middle is deformed and compressed like warped plastic, sliding (basal slip) occurs at base. can flow few cm / yr or few meters/ day

* Alpine glaciers: form on mountains and flow down valleys
* Continental glaciers: form at higher latitudes and flow to lower latitudes

Moraines-- landforms made of Till (the unsorted, unlayered sediment deposited directly by glacial ice; can be fine as clay or large as boulders)

* lateral and medial moraines: linear strips formed along edge of *alpine* glacier
* end moraine: curved, elongated ridge that accumulates at the “downstream” end of glacier
* terminal moraine: marks glacier’s farthest advance
* recessional moraine: a lateral or end moraine formed during a pause in a glacier’s retreat
* ground moraine: till that is deposited along the base of a glacier

What are some types of evidence for glacial activity in the past?

Erratics “imported rocks”

Till, including moraines

Depression of the land

Scouring (striations + grooves)

Lowering of sea level

Migrations of species

Evidence of past

* long island, martha’s vineyard, cape cod, nantucket island were formed from end moraines

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What are two external and three internal factors that can cause global climate change?

External causes:


1. solar output variations (10% birghter?) appear to be too small and short-lived at present, but may have been larger in the past or may be larger than we think
2. Milankovitch cycles (orbital fluctuations): separate cycles on different time scales, but periodically experience collective reinforcements that are enough to cause global climate change


1. eccentricity: ellipticity of earth’s orbital path -- 100,000 year cycle
2. obliquity: degree of tilt of earth’s rotational axis -- 41,000 year cycle
3. precession: wobble of Earth’s rotational axis over time -- 26,000 year cycle

Internal factors:


1. The Albedo Effect: the percentage of solar radiation that is reflected back into space changes the amount of energy available to heat the planet
2. The Greenhouse Effect: gases effective in absorbing long-wave (infrared) radiation effectively strengthen the effect of solar radiation
3. Plate tectonics: changes in geography influence activity of ocean currents, atmospheric co2 levels, distribution of heat, present or absence of lands at poles, etc.

(2 other internal: volcanic activity and changes in biogeochemical cycles)

What were the main factors that led to cooling and eventual glaciation throughout the latter part of the Cenozoic? Why is it correct to say that we are still in an “Ice Age”?

factors of Pleistocene glaciation include tectonics and ocean circulation

* closure of Tethys Sea (Oligocene) limited warm water flow . placement over South Pole established Antarctic circumpolar current. Uplift of Himalayas lowered atmospheric co2. Together, these events led to Antarctic ice sheets, which accelerated formation of oceanic waters.
* after some time, formation of Isthmus altered NA circulation and glaciation had begun

The division between Pleistocene and Holocene falsely implies that the “ice age” is over (no, but, interglacial?)

This ice age has been going on for 2.6 million years. Ice sheets have expanded and melted at least 17 times in the last 2 million years.

How do oxygen isotopes of glacial ice and marine microfossils inform us about glacial-interglacial cycles?

oxygen isotope data correlates to temperature

oxygen isotope compositions of shells of planktonic forams provide global temperature information

isotopic mass fractionation , the back and forth between heavier, warmer temp isotopes (o18) and lighter, cooler isotopes (o16) , preserve a record within glacial ice of the fluctuating global temperatures over time.

* trapped air bubbles in glacier ice also show paleoatmospheric composition (greenhouse gas concentrations!), as well as a bunch of other environmental data (like volcanic history for example)

What are the orbital fluctuations associated with Milankovitch cycles and how have they affected the behavior of ice sheets during the present “Ice Age”?

eccentricity + obliquity (tilt) + wobble = glaciation fluctuation

by combining the above aspects of Milankovitch cycles, we get a plot of “solar radiation received” that matches very well with global temperature fluctuations indicated by ice core oxygen isotope data.

\-- geologists are somewhat unsure *why* this happens, but the evidence is clear that it does

What about the Pleistocene terrestrial mammal fauna of North America and Europe was different than today’s mammals on those continents? What are the two main hypotheses concerning their extinction and which one is currently favored and why? What are some of the megafauna that went extinct at the end of the Pleistocene?

Terrestrial mammal fauna of NA were much larger than their modern counterparts

__Herbivores__: elephants (mammoth, mastodon), beaver size of bear, camel (20% larger), bison w 7ft horns, 1 T weighted armadillos, 3T weighted ground sloths

__Carnivores__: larger bears, dire wolf (30% heavier), lions (1.5x as heavy)

Teratorns: large flying predatory birds

What were the largest known flying birds?

TERATORN (*Argentavis*)-- wingspan of 24 ft

related to storks, modern turkey vultures, and condors

What are the effects of the uplift of the Himalayas toward their status of the world’s highest mountain chain on global climate and what is the mechanism by which rising mountain ranges result in a cooling climate?

weathering of Himalayas caused decrease in atmospheric CO2 levels, which results in lower temperatures and changed precipitation patterns

(don’t know answer to second question. weathering?)

What event caused the “Great American Interchange” and how did this exchange of taxa affect the biota of North America? How did this event affect global climate?

‘The Great American Schism’ was the joining of N. American and S. America 3-5 Ma when the Isthmus of Panama arose as an island arc.

S → N : monkeys, anteaters, armadillos, porcupines, opossums, sloths, etc.

N → S: camels, pigs, deer, horses, elephants, tapirs, rhinos, rats, skunks, squirrels, bears, dogs, raccoons, cats, etc.

* more animals went southward than northward because NA had fewer tropical habitats by Pliocene time.
* marine species in Caribbeans and Pacific began to evolve differently from one another: speciation + extinction

Climate Effects:

* Caribbean waters became warmer, saltier, stable.
* Gulf Stream delivers warmer water to North Atlantic
* Pacific waters became cooler and more nutrient rich

Which taxa arrived in Africa from Asia after Africa joined with Eurasia, and how successful have these animals been in Africa over time?

Asia → Africa Invasion of the “Mongol Hordes”

* Suids
* Giraffids
* Rhinos
* Bovids
* Fissiped carnivores (toes separated at base like dog)

What climate changes led to the evolution of C4 grasses? Why did C4 grasses become dominant over C3 types?

Shift toward increasingly drier and cooler climate in Miocene led to evolution of C4 grasses

Compared to C3 photosynthesis, C4 is more efficient in drought conditions, high temperatures, or CO2 shortages

C4 plants are less selective about needed carbon-12 isotope; over time carbon-13 was more prominent

How and why did these climate and food source changes (e.g., C3 to C4) affect mammal evolution on North America?

Because C4 grasses have sharper phytoliths, grazers who evolved high crowned teeth rose in dominance (browsers decline)

in addition, flowering herbs rose in plant dominance.

The combination of grasses and herbs resulted in diversification of smaller rodents and songbirds with corresponding diets. → snake diversify

Mammals evolve

Herbivores (Artiodactyls like deer and bovid & elephants) & Omnivores (giraffes and pigs)

Carnivores (families of dog, cat, bears, hyena) benefitted from herbivore expansions

What major changes occurred during the Neogene regarding marine life and why did they occur?

diatoms underwent tremendous diversification (maybe driven by C4 grasses)

corals, and other warmer water taxa, became restricted to lower latitudes due to cooling

whales radiate and diversify

* Toothed whales : predators - first
* Baleen whales: “filter feeders” - evolved later from toothed whales

Cause: calcareous (coccolithophores + foraminifera) and siliceous (radiolarians) oozes and red clay on the ocean floor established due to vigorous deep ocean circulation, upwelling of cold nutrient-rich waters, and deepening of calcite compensation depth

How did the expansion of grasses and herbaceous plants lead to the evolution of songbirds, small rodents (rats and mice), and modern snakes?

\[Cascading radiation & diversification)

The evolution of grasses and herbaceous plants required the help of small animals to distribute seeds.

The diversification of these small rodents (mice, rats) and songbirds corresponded with grass/herb/seed diets.

In turn, snake predators diversified to pursue rodents into their burrows and to climb trees to reach songbirds eggs/chicks

What features distinguish primates from other mammals, and where, when, and from what type of mammal did primates likely arise?

Features:

Large eyes, turned forward for effective steroscopic vision

grasping hands and feet allow primate to forage alone narrow branches

nails instead of claws

primate fetuses have rapid brain growth rates so theyre born with larger brains than other mammals

gestation time is long for body size, and primates have small litters of young that develop slowly and for a long time

primates have evolved high learning capacity, complex social interactions, and unusual curiosity

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Origin of Primates

85 million years ago in the tropics

most closely related to *dermopterans*, “flying lemurs”

What are the two living groups of primates and the three living groups of anthropoids?

2 primate groups == Prosimians “wet nose” + Anthropoids “dry nose”

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Prosimians: small-brained, small-bodied

* Lorises (nocturnal insect hunters living in tropical forests of india, sri lanka, south asia) + Pottos (nocturnal tree-dwelling omnivores of tropical africa -- short fingers)
* Lemurs: fossil record to Miocene. confined to madagascar

Anthropoids: relatively large-bodied and large-brained monkey and apes.


1. ceropithecoids (old world monkey): macaque, baboon, mandrills, colobus
2. Ceboids (new world monkey): monkey type-- spider, howler, emperor, tamarin
3. hominoids: gibbons, apes, humans - longer arms + no tail . swing *underneath* branches

What are the five groups of living hominoids? Approximately when did hominins split from their common ancestors with chimpanzees?

hylobatids (gibbons), pongids or asian apes (orangutans), african apes (chimps + gorillas), and hominins (humans)

certainly evolved from Aegyptopithecus , an African anthropoid genus

Humans made split from common ancestor around 7 Ma

What hominoid is the best candidate for the Sasquatch or Yeti? When and where did they finally go extinct?

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The hominoid Gigantopithicus went extinct at the beginning of the Pleistocene’s last ice age in tropical forests of modern day China-- changed climate made its size a fatal handicap

Hominin evolution: What are the defining features of *Homo sapiens*? In what order did these traits evolve and which of our ancestors first developed these? With which fellow hominin did *Homo sapiens* apparently interbreed and how do we know this?

Features of *Homo sapiens* (in chronological order) : small canines, thick enamel, bipedalism, big brains, tool-making, meat-eating, big bodies

DNA evidence shows there was interbreeding between *Homo sapiens* and Neanderthals (*Homo neanderthalensis*)

* 2.5% of average non-African human’s genome is made of Neanderthal DNA; 0% in modern Africans

Where were the fossils of *Ardipithecus ramidus* found, what do they show about this hominin’s behavior, and what role did Miami’s own Dr. William K. Hart play in our understanding of them? Why is the East African Rift (Afar Triangle) such a good place to find and date early hominid fossils?

Fossils of Ardipithecus, found in Middle Awash, Ethiopia (2009), show adaptations that combine tree-climbing AND bipedal activity

* Ardi (ground) pithecus (ape) ramidus (root) = “root of all ground apes”

Dr. William K. Hart chemically analyzed and correlated the ash layers associated with fossils to ash layers dateable by the Ar/Ar method. Found that Ardi fossils \~4.42 Ma old

East African Rift Valley -- over 30 million years of episodic bimodal (basalt-rhyolite/trachyte) continental rift volcanism AND extensional tectonism (uplift and subsidence) and sedimentation

* \[\[ find out why its a good site\]\]

What evidence has been discovered to suggest that the rise of bipedalism in hominins was not driven by the \n transition from woodlands to savannas? Did bipedalism arise before or after large brain size evolved?

The transition from woodlands → savannas did not drive bipedal evolution

* Ar. ramidus fossils showed wooded environment -- forest-to-woodland based diet

Bipedalism evolved before large brains

Describe the overall climate of the Paleocene and Eocene. What types of terrestrial plants and animals succeeded in this climate and in what general type of environment did they live?

Climate of paleocene-eocene: Very warm (like cretaceous) and experienced 10,000 year long thermal maximum -- temperature spike

What are some of the important marine organisms of the Paleogene?

Coccolithophorids survive K-Pg event, but never recover their former diversity

Nummulitids: 1in disc-shaped forams become important limestone builders in shallow seaways (pyramids)

Hexacoral, took until late eocene bc mg2+/ca2+ ratio was too low

Echnoids continue their dominance of echinoderm fauna, sand dollars evolve

Giant predatory sharks replace marine reptile

Origin of whales, manatees and sea cows, desmostylians, seals, and sea lions

What likely led to the occurrence of the PETM? What were the main effects of this event on marine life, insects, and plants? Why is the study of this event relevant to our modern climate?

PETM: Paleocene-Eocene Thermal Maximum

Heat spike : 4-5 C increase; 3-4x co2 increase

Possible causes: Positive feedback loop of methane gas release

release, reduced burial of C, Iceland Hotspot triggering volcanism (initial catalyst)

Increased pCO2 on marine life, insects, and plants:

* marine life: warming caused o2 depletion, dissolution of calcium carbonates (caco3) / 70% extinction of benthic (bottom dwelling) forums; shallow were fine
* Insects: CO2 does not directly affect insects (but developmental decrease occurs since foods (plants) nutritional content had decreased)
* Plants: Growth rates increased and nutrient content of plants decreased

Relevant to modern climate because PETM provides best known analog for understanding impacts of modern-day global warming and massive carbon input to ocean + atmosphere

How did the initiation of the Antarctic circumpolar current change global climate starting in the Middle Eocene? How did these changes affect the evolution of mammals?

Initiation of Antarctic circumpolar current due to separation of Antarctic and Australia isolated Antarctic from warm-water currents and caused continuous circular water flow which reduced deflection toward lower latitudes -- allowed right amount of moisture for glacier building

Cooler, drier climates changed the course of terrestrial evolution

* forests heavily reduced, leaving grasslands and savannas.
* Lost habitat and food sources for forest-dwellers, loss of cover for ambush-style predators -→ out competed by running carnivores
* Toed hooves left, morphed one for faster running
* Continuous tooth growth

What is so important about the advent of continuous growth in grasses? How do grazers teeth cope with the presence of phytoliths in grasses?

Pre-Paleogene grasses could not tolerate continual grazing, so they occupied moist swampy areas

Advent continuous growth allowed later grasses to grow back quickly after grazing, allowing grasses to spread and forests shrank in dry conditions of Oligocene

Phytoliths: Silica structures in grass makes chewing it like sandpaper, it grinds teeth down over time. Grazers adapted with high-crowned teeth for continuous tooth growth. When tooth eroded, more would be pushed out.

\* grassland expansion was very important to evolutionary changes in mammals

Why was the Laramide Orogeny unique? Where did the sediment of Badlands National Park originate and why are the fossils in these rocks so important to our understanding of mammal evolution?

Late-cretaceous Laramide orogeny: Subhorizontal subduction brings volcanism (high -→ angle change) to Colorado, Wyoming, new Mexico

Formed Unita and Green River Basins

Unique because the Badlands of South Dakota, which consist of sediments eroded from Rocky Mts, contain a very valuable fossil record of Early Cenozoic mammal and plant evolution.

What was the Younger Dryas, what caused it, and what about is so shocking about the end of this interval?

Cenozoic Era - Quaternary Period - Holocene Epoch

The Younger Dryas, “the big freeze”: a cold (and dry) interval between 12.8 ka and 11.7 ka, followed by rapid warming which interrupted thermohaline circulation

* linked to humans first adoption of agriculture in Middle East

chain of events:


1. (12.8 ka) warming-induced flux of water to Atlantic or Arctic Ocean due to collapse of N. American ice sheets, which deflected northward flow of warm saline from south → rapid cooling and drying of northern latitudes
2. cooling persists until fresh water ‘lid’ is removed form N. Atlantic Ocean
3. (11.7 ka) ends with *rapid warming of 7C in 3 years*, resulting in rapid positive feedback

What are some important Holocene climate fluctuations with respect to human populations and what effects did they have? What happened as a result of the 1815 eruption of Mt. Tambora in Indonesia?

Holocene Climate Optimum: Warm and wet climate (post Younger Dryas) caused favorable conditions for human agriculture in Middle East “Fertile Crescent”, then in Egypt, Mesopotamia, etc., and finally to Europe

Transition into Neoglacial, cool and dry climate which brought severe droughts and famine → creating a need for complex governments. sudden and severe drought led to “Dark Ages”

* possible catalyst for barbarian migrations leading to fall of Roman Empire

Medieval Warm Period 950-1250 CE was 1C warmer than today (oof) causing max. solar output, deforestation of Europe, low volcanic activity, stronger Gulf Stream \[weirdly tho, global temp avg. was lower\] → Norse Vikings + Europeans flourish, Mayan civilizations collapse from drought.

The Little Ice Age: N. Hemisphere Event: cooler/wetter post-MidE-warm p. caused European famines in 14th-15th century, leading to the downfall of N. African and Indian civilizations, famines/floods in china

1815 Eruption of Mt. Tambora (Indonesia) was the largest volcanic eruption in history -- ash fell 810 miles from site. Led to the “Year Without a Summer” in 1816, global temp dropped up to 1.4F

* agricultural disaster in N. Hemisphere-- greatest subsidence crisis in Western world
* New England (below freezing, sow, frost, and river ice through summer months), failed harvests in Europe, disrupted monsoon season in Asia

→ human adaptations: bicycle (no horses), Frankenstein, settlers move to midwest, invention of mineral fertilizers

What is the main cause and magnitude of Holocene sea level fluctuations and why are they important to human civilization?

Glacial maxima of Holocene epoch show sea level falling 330-450 ft, causing land bridges (allowing animals to cross), increased fluvial downcutting (fjords + terraces), and acceleration of sediment delivery to the ocean, with sand often bypassing the continental shelves

* important to note that if glaciers melted, sea level would rise 210ft, drowning 15% of land area + higher temp expands water volume

Why do we think that simple extrapolation of current climate trends into the future is not likely to provide an accurate predictions about climate change?

simple extrapolation of current climate trends is unhelpful since tipping points are reached which may cause rapid positive feed back loops:

* loss of Arctic sea ice will result is region warming instead of ice melting in summer heat
* evergreens replacing tundra changes albedo in northward and in Greeland.
* progressive release of methane (23x worse than co2)

What arguments can be made for and against establishing a new “Anthropocene” epoch, and if it were adopted, what are the possible starting times for it?

Its been proposed that the “Anthropocene Epoch” be validified as a geologic time of humans disrupting climate and ecosystems but, because its generally short and unsustainable, the Anthropocene would be better categorized as an event.

If adopted, possible start times are: Industrial Revolution, Neolith (deforestation/ agriculture), 1st atomic bomb detonation

Based on our understanding of mineral “evolution” on Earth, why would we expect the diversity of minerals on a planet to remain at an early-established low value unless life evolves?

We expect a diversity of minerals on a planet remain at low established value until life evolves because we know that the mineralogy of terrestrial planets and moons evolves as a consequence of selective physical, chemical, and biological processes.

What two main events associated with biological processes greatly increased the diversity of minerals on Earth?

Stage 7: “The Great Oxidation Event”

* rise of oxygenic photosynthesis and rise of an oxygen-rich atmosphere (2.5 - 1.9 Ga):
* more than 2500 minerals are hydrated oxidized weathering products of other minerals

Stage 10: biologically-induced weathering and biomineralization as life dominates and diversifies

* invertebrate and vertebrate animals begin to use carbonate, phosphate, and silica through new mechanisms of mineralization (0.542 Ga - present)
* rise of land plants about 400Ma led to rapid soil production and an order of magnitude increase in the rate of clay mineral production

Why does the concept of mineral evolution potentially inform the search for life on other planetary bodies?

By looking whether the following processes are acting at or near a planet’s surface will determine its degree of mineral evolution, and therefore, its closeness to life

* progressive separation + concentration of elements from their OG distribution in the presolar nebula
* activity involving pressure, temperature, H20, CO2, and O2
* the production of thermodynamically metastable minerals and mineral-forming reactions that could not occur abiotically