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Marine Photosynthesis is restricted to the:
Photic Zone
Rocks are solids never made of several mineral crystals
False
According to Steno’s Principles of Superposition, which of the following is true:
Sedimentary layers appear in a stratigraphic sequence such that the oldest sediments are at the bottom and the youngest are at the top
If a shale was compressed and heated such that its mineral grains aligned and recrystallized without melting, what type of rock would the resulting solid be?
Metamorphic
If presented with a stratigraphic sequence that included, from bottom to top, a deep-sea limestone, shale, siltstone, and sandstone containing trace fossils representing shallow water, how might we interpret the history of environmental change?
Marine regression
Which of the following would we consider events in “Earth History” that can be addressed through historical geology?
Indian subcontinent colliding with Eurasia
A lake drying up and leaving an evaporite flat
A river meander getting cut off and forming an oxbow lake
Which of the following are qualities of a good index fossil?
Organism existed for a short amount of time
Extinction of the organism took place quickly
Organism had a global geographic range
If a sandstone was melted to a liquid state and resolidified, what type of rock would the resulting solid be?
Igneous
Which of the following statements would be an example of uniformitarianism?
Rivers deposit sand which becomes sandstone in the present, therefore ancient sandstones could have originally been sand deposited by ancient rivers
Of the following minerals, which would you expect to be most common in the Earth’s crust?
Feldspar
Continents at and near the equator receive a lot of rainfall relative to the more desert-dominated regions to the north and south of that wet tropical zone. Which of the following accounts for this higher precipitation around the equator?
Hot air rises at the equator and drops moisture as it does so
Which of the following may be indicative of the facies of a sandstone?
All of the above
Which of the following interpretations might we make if we find a stromatolite preserved in sedimentary rock?
Prokaryotic organisms were active at the location at the time of formation
Which of the following is an example of evolution by natural selection?
A group of snakes are less likely to be eaten if they are darker in color, as predators remove snakes of lighter colors, the population shifts towards darker colors overtime
Geologic Eons are divided into Eras. Which of the following are Eras most directly divided into?
Periods
Which of the following are among the defining characteristics of minerals?
Naturally occurring
Crystalline structure
Solid
Inorganic
Relatively consistent chemical composition
Silicate minerals are defined by containing tetrahedral molecules of SiO4 (sometimes also expressed as SiO2).
True
Which of the following processes represents the way that minerals form in an igneous rock?
Freezing
In what type of environment should we expect asymmetrical ripples to form on the surface of a body of deposited sediment?
In water that is flowing one direction, like a river or stream
Cnidarians are never preserved in the sedimentary record because they do not produce mineralized skeletons.
False
Which of the following was the most recently acquired piece of evidence for plate tectonics?
Mapping of the seafloor capturing and measuring spreading at mid-ocean ridges
Continental crust is thinner and more dense than oceanic crust
False
What tectonic setting exhibits the highest concentration of earthquakes?
Convergent boundaries
What would the structure be called if there is a linear fold with rock layers dipping away from the central fold axis?
Anticline
Which of the following is the largest reservoir of water?
Groundwater
In the process of evapotranspiration, where is water moved to and from?
From soil to the atmosphere
Which of the following would result in the drawdown of carbon dioxide from the atmosphere (even if somewhat indirectly)?
Weathering of continental rocks
In a case of eutrophication, excess dissolved nutrients contributes to the depletion of oxygen in water.
True
Greenhouse gases in the Earth’s atmosphere contribute to warming of the Earth by absorbing are reradiating long-wave radiation that was previously radiated by the Earth’s surface (having already absorbed short-wave radiation from the sun).
True
What of the following types of surface should we expect to have the highest albedo?
Glacial ice
Which can serve as proxies for climate conditions in the distant geologic past?
Fossils, rocks that form in specific climates, stable isotopes in mollusk shells
How are isotopes of the same element different?
Different number of neutrons
If for a given radioactive isotope 2 half-lives have gone by, what proportion of the original parent materials is still present?
25%
Uranium-lead dating used on a grain of the mineral zircon found in a sandstone would tell us which of the following?
The time since that zircon grain reaches its closure temperature as it cooled from melt
Paleolatitude can be recorded in rocks that contain evidence of magnetic inclination.
True
The original environment in which the precursors to coal form are places with:
High precipitation
Most meteorites are approximately 4.6 billion years old
True
Which of the following contains the oldest crust?
North-eastern Canada
Which is NOT true of prokaryotes?
They are more restricted in terms of the types of metabolism they can exhibit relative to eukaryotes
Which is most likely a place for life to have originated on Earth?
Hydrothermal vents
What describes tectonic settings of the coastlines of Laurentia during the Cambrian Period?
Passive margins all the way around the continent
Coastlines of Laurentia during the Ordovician Period?
A subduction zone one one side of the continent and passive margins around the rest of the coastline
Silurian Tectonics
Salinic Orogeny
Follows Taconic Orogeny
Microcontinents collide with Laurentia
Now, Laurasia
Devonian Tectonics
Acadian Orogeny
Andean-type subduction
Oceanic crust subducting under continental crust → causes crustal thickening → uplift
Continues to uplift “Appalachian” region
Carboniferous Tectonics
Beginnings of the Alleghanian Orogeny
Gondwana collides with Laurasia → Pangea
MASSIVE uplift
Himalayan-scale mountains
Similar scale to how to mountains would be like during this period
Permian Tectonics
Alleghanian Orogeny continues
Pangea is built
Triassic Tectonics
Rifting of Pangea has begun
Pangea beings to rift
elongated lakes at rift basins
Silurian Climates
deglaciation
high sea levels
extensive shallow marine environments
Devonian Climates
warm through most of the period
Glaciation becomes prominent at south pole (Gondwana) toward the end of the period
ice cap forming again on Gondwana
Drawdown of CO2 causes south pole glaciation at the end
Carboniferous Climates
Generally warm temperatures
Beginning in Pennsylvanian, temps drop and:
Glacial-interglacial cycles begin
Milankovitch forcing
Permian Climates
was a global icehouse
large igneous province volcanism (short period of low viscosity volcanic activity) —> influx of atmospheric carbon
temps and ocean acidification goes up
Triassic Climates
hothouse
Pangea is one giant desert
Cause and Mechanisms of end-Permian mass extinction
flood basalt volcanism/LIP erupts through peat and coal —> a lot of burning and CO2 release
warming melts ice (less reflectiveness = more heat absorption), destabilizes permafrost and releases methane, and causes forest fires —> WARM
sea levels rising —> loss of coastal habitat
ocean acidification via CO2 —> no one can calcify and reefs collapse
Algal booms via CO2 —> eutrophication and suffocation of bottom dwellers
Acid rain kills plants —> desertification
warming that is reducing ice/snow
losing ice caps
reflectiveness of Earth is lower
losing methane hydrates
forests have been prevalent and common for a whole —> warming = forest fires
fires are much more common due to warming
carbon tied up in biosphere is now also becoming released at this time
End-Permian Mass Extinction
Compounding Effects:
rapid warming —> sea level rise —> habitat loss in coastal and near-shore environments
carbon dioxide dissolved into ocean —> ocean acidification —> marine organisms can’t calcify anymore —> reef collapse
carbon dioxide serves as fertilizer for marine phytoplankton —> algal blooms —> choke out light and dissolved oxygen in body of water —> causing other organisms to suffocate
hydrogen sulfide emissions and desertification
Effects of the rise of Devonian forests
root systems become deeper and more complex —> better at retaining sediment
Late Paleozoic to Early Mesozoic Life
Colonization of land
Devonian forests
Arthropods (millipedes, centipedes, arachnids) move onto land in Silurian/Devonian
Early Devonian Trees
taller (~1 meter), a bit more complicated
larger (not very large)
reproduce by spores, not seeds
produce individual cells
prone to desiccation and starvation
spores have to be present in a climate
can only live in moist environments
Late Devonian Trees
trees become common
widespread forests
forests become ecologically significant —> trees
no seeds yet — can’t move into dry habitats
ex.) Archaeopteris —> A 12 m tree that formed early forests (Late Devonian Forests)
Arthropods
move onto land in Silurian and Devonian
Millipedes, centipedes, arachnids, insects
whole bodies under exceptional conditions
Major evolutionary developments to facilitate life on land
lobefin fish had fleshy, muscular appendages at bases of fins —> tetrapod ancestors
stem tetrapods: amphibians, some aquatic some terrestrial, but had eggs in water
Ammonite eggs allow tetrapods to move inland
Lobefin Fish
ancestors of tetrapods (land vertebrates)
fleshy, muscular appendages form bases of fins —> arms and legs
modern coelacanth, lungfish
Stem Tetrapods
amphibians
lay eggs in water
breathe air as adults
not much like modern amphibians, which appear in the early Mesozoic
some were more aquatic, some more terrestrial
common in Carboniferous-Permian
Outcomes of end-Permian mass extinction
LARGEST EVER
delayed biotic recovery
reefs eliminated
reduction in size of many marine taxa
resurgence of stromatolites
devastates Paleozoic fauna, modern fauna survived and took over
Permian Mass Extinction
largest ever
~83% of marine genera went extinct
~70% of terrestrial vertebrate species go extinct
plants and insects affected too (loss of plants and insects)
extinct
trilobites
rugose and tabulate corals
major groups of brachiopods, crinoids, bryozoans, ammonoids, therapsids, and reptiles
250 mya
devastates members of the Paleozoic Fauna
the Modern Fauna survived well and took over in its aftermath (although it was present before, too)
the living fauna consists of the survivors of this extinction
Effects of Extinction in Permian
delayed biotic recovery: millions of years of low diversity
reefs eliminated
reduction in size of many marine taxa
resurgence of stromatolites
Features of rocks of Newark Supergroup
rift basins on East Coast
Fluvial facies: immature (poorly sorted, large grains), Arkosic sandstones
Ripple marks and mudcracks —> shallow waves and drying
Basalt ridges from Central Atlantic Magmatic Province (erode slower than other rocks)
East Berlin Formation: red mudstone and sandstone (lakes) and dark shale (deeper)
What do the rocks tell us about tectonic and geologic history of the East Coast (Newark)
North America is rifting from Pangea
Rivers change direction and lakes form, causing sediment to accumulate in wedge shapes
Climate change in East Berlin Formation: lakes changing depth
Volcanic activity from Central Atlantic Magmatic Province
Fault occurring east ward
Basin became more steeper
East side is doing the faulting = more steep
Rifting occurring at East
Fossils of Newark Supergroup
Invertebrates (clams, insects)
Fish
living in freshwater
Hartford Basin Fish
Terrestrial vertebrates: lots of dinosaur tracks but few bones
bones dissolve in acidic conditions
tracks remain as long as they are undisturbed, sediment fills in and creates a cast
Early Jurassic: lots of dinos, some small crocs and lizards
Plateosaurs, lesothosaurs, coelophysis, dilophosaurs
Bone dissolve under acidic conditions
Require particular chemical conditions in the sediment for preservation
footprints are basically sedimentary structures
if the sediment isn’t disturbed, the print will remain
little bone material
footprints don’t require specific chemicals for preservation
Jurassic Tectonics
rifting of Pangea
Beginnings of Sevier Orogeny in Western NA
subduction
thrust belt (scrunching up of crust)
shallow —> sed rocks that are deposited and being thrusted
Andean-style volcanism
small, narrow oceanic basin
going farther south
Cretaceous Tectonics
Atlantic widens
Tethys narrows
Laramide Orogeny
NA Carton fractures
Intense crustal thickening
Fracturing at depth —> new reverse fault
a lot of land area exposed
Marine fossils on land far away from ocean now —> due to the stretching and sea level over time
Paleogene Tectonics
Atlantic continues to widen
Tethys continues to narrow
India on collision course with Euraisa
Jurassic Climates
generally warm and humid
deserts and seasonally wet climates common on large continents
semi-arid climate still
Triassic deserts have been divided
Cretaceous Climates
lots of coastlines and shallow seas
Deccan Traps volcanism at end
Paleogene Climates
global greenhouse conditions
warm and humid relative today
Paleocene-Eocene Thermal Maximum (PETM) —> spike in temp followed by decrease
Causes of K-Pg mass extinction
Chicxulub impact and Deccan Traps volcanic event caused big environmental changes
Chicxulub caused:
massive dust cloud: blocked sun —> loss of primary productivity and global cooling
greenhouse gases released —> warming
vaporization of sulfur —> acid rain
widespread wildfires
tsunamis
Chicxulub Crater: Identified in the late 1980’s by geophysical imaging and drilling. Called the “smoking gun.”
Chicxulub impact: a ~10 km diameter asteroid triggered environmental disruptions
Evidence for asteroid impact
Iridium anomaly: 300 times normal concentration
Shocked quartz: high pressure generating parallel fractures
Glassy microspherules: rock is melted on impact and sprayed and freezes in air as drops
Iridium Anomaly
Tertiary
Cretaceous
300 times the normal concentration of iridium
Rare in the Earth’s crust but common in some asteroids
common in concentration in asteroids
The K/T iridium anomaly has been found in over 100 localities around the world. Such anomalies have proven to be extremely rare in general in geologic time
Deccan Traps volcanic event
large scale volcanic event over India
Carbon gases released —> greenhouse effect
Hydrogen sulfide gas —> acid rain and lowered temps on short scale
variable climate
Deccan Traps
Outgassing
Acidification
Variables Climate
Thickness > 2000 m
Area ~ 500,000 km²
Volume ~ 1.5 million km³
Jurassic Plants Gymnosperms and spore-bearers
conifers
cycads
ferns horsetails
Angiosperms
flowering plants
showing up in late Cretaceous
many are pollinated by animals, esp. insects
insects diversify along with angiosperms
first fossils from the Early Cretaceous
Common in the Late Cretaceous
Dominant in many ecosystems in the Cenozoic
Sauropodomorphs
Prosauropods —> sauropods
smaller four limbs —> heavier four limbs (heavier bodies, longer tails and necks)
Therapoda
Bi-pedal Dinosaurs
Carnivores (in Mesozoic)
start to get birds
Feathers on Theropods (Caudipteryx)
feather visible on tail
preserved feathers
feathers on various dinosaurs
Herrerasaurus
traditionally considered a theropod
look like theropods, and were included with theropods
Ornithischia
bird-hipping dinosaurs
sub set
getting our build dinosaurs, frills, horns, prominent back plates/spikes
birds evolved from lizard-hipped dinosaurs
Psittacosaurus
an ornithischian (ceratopsian) with feather-like structures. Was this ancestral dinosaur characteristic?
doesn’t have the frill
small —> size of a small dog
preservation of hair-like quills
eventually yields feathers
Ornithischia versus Saurischia
Ornithischia (bird-hipped): a branch of the pubis bone points backwards, resting against the ischium, increasing the space for intestines
Saurischia (lizard-hipped): pubis points forward, except in the bird clade
point forward
Archaeopteryx
Late Jurassic
Earliest known theropod with powered flight (= first bird)
able to fly short distances —> not like modern birds
had flight feathers, but would not have been a skilled flier relative to modern birds
retains many theropod traits (teeth, long tail, unfused wrist and ankle bones, etc.)
soft body features
Cretaceous Birds
more and more “bird-like”
Late Jurassic
Getting more like modern birds
tail features
aquatic life
propelling off of feet, not with wings/features
Pterosaurs
Late Tri-Late Cretaceous
Archosaurs — but direct ancestors unknown
Lightly built with air spaces in bones and powerful flight muscles
teeth well-suited for catching fish
sometimes preserved with scales in their stomachs
birds were light in order to be able to fly
some had teeth, but more beak-like structures
Mammals
mostly small and egg-laying mammals
fossil record consists mostly of teeth
By the Cretaceous, there are marsupial and placental mammals (non-egg laying)
show up in Mesozoic
Diversify after the K-Pg extinction
Cretaceous Plants as Before, Plus Angiosperms
Pollination by animals may have led to faster speciation
produce seeds more rapidly than gymnosperms — can reproduce faster. Allows annual life cycles, colonization in unstable environments, “weedy” life habits
should have feathers
angiosperms
Rudists
bivalves that look like corals
formed mounds or reefs
show up in Cretaceous period
Grown asymmetrically
resting on sift sediment
growing in numbers producing reefs
Turtles and Crocodiles in the Jurassic and Cretaceous
common as aquatic and semi-aquatic predators
successful in seas and estuaries
very large turtle bones were found
Other Mesozoic Marine Reptiles
Ichthyosaurs: Early Triassic-Late Cret
fish like
Plesiosaurs and Pliosaurs: Late Triassic-Late Cret
large flippers
Mosasaurs: Late Cret
related to lizards and snakes
Teleost Fish
dominant modern group
Radiate in Meso-Ceonozoic
Maneuverable
Mobile jaws improve prey capture/feeding
Body Size of Marine Animals
mean size goes up from Paleozoic to Cenozoic
large animals getting larger
Diversification of Modern Phytoplankton
theory: more food —> larger, more active animals and more predators
Cretaceous Extinction
almost 50% of marine animal genera died out