GEO 3200
EARTH THROUGH TIME

r

LECTURES

  LECTURE OUTLINES

Topic 1-Introduction to the course and Historical Geology
Topic 2-Birth of the solar system
Topic 3-Earth Materials
Topic 4:  Geologic Time
Topic 5:  Sedimentary environments
Topic 6:  Stratigraphy and the geologic time scale
Topic 7:  Evolution
Topic 8:  The early Earth: Hadean (Eoarchean) and Arcehan time
Topic 9:  The Proterozoic Eon
Topic 10:  Arrival into the Phanerozoic--The Paleozoic Era
Topic 11:  The Mesozoic Era
Topic 12:  The Cenozoic Era

HANDOUTS
timescale v1
study guide for exam 1
study guide for exam 2
field trip equiptment list
writing assignment 1
writing assignment in lieu of 1
study guide for exam 3
study tips for final exam

COOL LINKS
 

 

f

go home

 


















TOPIC 1-INTRODUCTION TO HISTORICAL GEOLOGY  (graphics)

Define geology, difference between the two branches (physical and historical)

Recall:  The Scientific Method

Benefits of Historical Geology to Society? (i.e., Who cares?)

Geologic time, Plate tectonics, Organic evolution


back to top
 
 
  TOPIC 2-EVOLUTION OF THE SOLAR SYSTEM AND EARTH (graphics)

Solid Earth-has it always been layered?

Compositional and rheological layering

O Si Al Fe Ca Na K Mg

Observations of current solar system as formulation of:

a.  Solar Nebula Theory

b.  Homogeneous Accretion Theory

c.  Big Bang Theory

Observations of current Earth as formulation of Plate Tectonics theory


How is Earth is different from other terrestrial planets?


back to top 

TOPIC 3-EARTH MATERIALS (graphics)

Elements and isotopes

Mineral vs. rock!

Major mineral groups and rock forming minerals...

Three rock types, how they relate to plate tectonics/rock cycle

composition and texture of different rock types (what are 3 rock types?)

Igneous rocks-textures, compositions, origins

Sedimentary-textures, compositions, origins

Metamorphic-textures, compositions, origins

TOPIC 4-GEOLOGIC TIME (graphics)

relative vs absolute dating

Werner and neptunsim

Cuvier and catastrophism

Hutton and uniformitarianism

concepts about geologic time:

Greek, biblical (Ussher), Kelvin, Darwin, discovery of radioactive decay

( Ernest Rutherford, who is considered the father of nuclear theory, spoke on the matter at a meeting at the Royal Institution in 1904; http://www.americanscientist.org/template/AssetDetail/assetid/55536/page/3;jsessionid=baa9...#55556). "I came into the room, which was half dark, and presently spotted Lord Kelvin in the audience and realized that I was in for trouble at the last part of the speech dealing with the age of the earth, where my views conflicted with his. To my relief he fell fast asleep but as I came to the important point, I saw the old bird sit up, open an eye and cock a baleful glance at me! Then sudden inspiration came, and I said Lord Kelvin had limited the age of the earth, provided no new source of heat was discovered. That prophetic utterance refers to what we are now considering tonight, radium! Behold! The old boy beamed at me." 

Geologic principles:

Law of superposition, lateral continuity, horizontality, faunal succession, crosscutting relations, and inclusions!

Types of unconformities....

absolute dating and radioactrve decay:

three types of radioctive decay--alpha, beta, neutron capture

half-life. parent and daughter elements

long-lived isotope systems for radiometric dating

fission track dating

carbon-14 dating

tree ring dating

dating igneous rocks

dating metamorphic rocks

dating sedimentary rocks

problems with dating--metamorphism, gas leakage, need closed system

age of the Earth

TOPIC 5-SEDIMENTARY ENVIRONMENTS (graphics)


importance of sedimentary rocks 

how to describe?  

texture and composition--what can these tell you about environment?

sedimentary structures--the fundamentals--what can these structures tell you about process?  about depositional environment?  (see Table 1 in Ch 6)

depositional environments:  continental, transitional, marine--what are key features that distinguish each of the following depositional environments?

continental:
alluvial fan
aeolian 
playa (siliciclastic or carbonate + evaporites)
other lakes (siliciclastic or carbonate)
braided streams
meandering streams

transitional:
deltas
tidal flat (siliciclastic or carbonate)
beach (siliciclastic or carbonate)
barrier island (siliciclastic or carbonate)
lagoon (siliciclastic or carbonate)

marine:
continental shelf (siliciclastic or carbonate)
continental shelf (siliciclastic or carbonate)


TOPIC 6-STRATIGRAPHY AND THE GEOLOGIC TIME SCALE (graphics)

sedimentary facies--define

Walther's Law

transgressions and regressions....define and causes

relative geologic time scale

stratigraphic terminology:
lithostratigraphic unit (group, formation, member)
time stratigraphic unit (era, period, epoch)
time-stratigraphic unit (system...)
biostratigraphic unit

index fossils and biozones

correlation

absolute dates and geologic time scale

fossils and fossil preservation
define fossils--
what rock types are fossils found in?
utility of fossils?  age and environment
organic evolution   

body fossils
    trace fossils
    preservation--how?  what is required for good fossil preservation?
        unaltered remains
        altered remains
            permineralization
            carbonization
            recrystallization
            replacement

TOPIC 7--EVOLUTION! (graphics)

evolution of evolutionary thought
biblical--"fixity of species"
Lamarck
Darwin and Wallace
Mendell and genetics
Genes and chromosomes
Mutations
Speciation
Species
allopatric speciation
rates of evolution:  gradual vs. punctuated....?
divergent and convergent evolution
parallel evolution
micro and macroevolution
mosaic evolution
extinctions!
data supporting the theory of evolution
tests of theory
classification (Linnaean)
biological evidence
fossil evidence

TOPIC 8--THE EARLY EARTH:  HADEAN (EOARCHEAN) AND ARCHEAN TIME (graphics)
Precambrian timescale--not based on time-rock units (exception:  Ediacaran Period)
    Why not?  fossil record, deformation, preservation
oldest rocks--4.03 Ga, Canada,  3.8 Ga Greenland
olderst mineral--detrital zircon from Precambrian fluvial deposits in western Australia
      implications --crust forming after 200 Ma of Earth history
                        --oxygen isotopes imply surface water
                        --Earth is not the fiery orb for 600 Ma as we thought before

earliest crust--low in siliciates, komatiites (extrusive equivalents of peridotite)
        komatiites form at 1650 C, so mantle was hotter in Archean and crust formation faster
        komatiites are found dominantly in Archean assemblages, therefore an indication of different crustal dynamics

craton, shield, platform,
Archean rocks--dominated by granites and gneisses
                    --greenstone belts
                    --some sed rocks including stromatolites, BIFS, turbidites, wackes

greenstone belts--komatiite and basalt pillows, wackes, folded into synclines and intruded by granites, cut by thrust faults
    two competing models for their formation--back-arc setting and plume genesis/intracratonic rift setting

Earth's early atmosphere
    very early--H, He
     early--CO2, H2O, SOx, NOx, CH4?, Cl, N--no free oxygen
          --evidence--uraninite and pyrite clasts
    How to get O2 in atmosphere?  photosynthesis and photochemical disassociation
        --both of these processes split water.  once ozone is established, photosynthesis dominates
    Water vapor in atmosphere and hydrosphere came from mantle gases
      3-6 X heat production in Archean, so lots of water vapor!

  Origin of life--

oldest fossils--3.3-3.5 Ga
oldest chemical evidence--3.8 Ga Carbon isotopes
low biologic diversity--non-photosynthetic bacteria
where did it come from?  (abiogenesis)
    outerspace?
    cosmic soup (Stanley Miller experiment)
    seafloor volcanic vents (black and white smokers)

TOPIC 9--THE PROTEROZOIC EON (graphics)

Big things happen in Proterozoic!  Crustal Growth, evolution of complex organisms, 2 or 3 supercontinents, low-latitide glaciations, oxygenation of the atmosphere, "normal" plate tectonics,

Where to start:  We are now becoming Laurentiapocentric--using the proto-North American continent as a proxy for global phenomenon....

Paleoproterozoic (2.5-1.6 Ga):  

major crustal accretion--we know this by observing regional belts of metamorphic and igneous rock of this age.  so, many arc collisions resulting in continental growth.  

BIFs galore--more BIFs during this time (>90%)--this is telling us that there was more free oxygen being introduced (probably directly related to photosynthesis), yet the oxygen was not always available,  hence the BIFs showing alternations of hematite (showing oxidizing conditions) and Fe-rich chert or carbonate (indicating no free O2 to bond with).

Paleoproterozoic glaciations--yes and widespread (300+ localities of glacial deposits of roughly this age).  Were these mellow Pleistocene glaciations?  or more like the severe Neoproterozoic ones??

Paleoproterozoic Supercontinent:  Nuna--our own Farmington Canyon Complex is a record of Nuna....

Oldest Ophiolite:  ~2.0 Ga--significance=often these record the closing of an ocean basin.  These sequences are a piece of oceanic crust..

Paleoproterozoic sedimentary record (in addition to BIFs):  sandstone, carbonate, and shale deposits common, 2.3 Ga is hey day of stromatolites, familiar sedimentary structures.  RED BEDS common by 1.8 Ga....

Fossil record:  oldest eukaryote at 2.1 Ga--endosymbiosis!, multicellular algae at 1.8 Ga


Mesoproterozoic (1.6-1.0 Ga):

Mesoproterozoic A-type (anorogenic) granites--perhaps not associated with subduction, but rather due to pooled heat beneath supercontinents...(some Paleoprot too, 1-8-1.1 Ga)

Mesoproterozoic supercontinent: Rodinia!  (assembled 1.4-1.1 Ga).  Culminating tectonic event was the Grenville orogeny.  Huge mountain chain that wrapped around southern and eastern Laurentia (in modern coordinates).  By this time, 75% of present day North America existed.  Mid-continent rift occurred at same time.

In Grand Canyon--sedimentary basin forms in response to Grenville Orogeny.  Beautiful red bed and basalt strata called the Unkar Group (1.2-1.1 Ga).  
Another super thick deposit from this general time period (1.4 Ga) is the Belt Supergroup--Montana, Idaho, Washington, Canada--up to 20 km thick! Some sort of interior seaway-continental deposit--correlatives in Siberia, so perhaps a supercontinent basin.

Acritarchs evolve at 1.4 Ga.  These are eukaryotes.  They are thought to be algae.  The remains are the cysts that the algae lived in during times of stress.  They were planktonic.  

Neoproterozoic (1.0-.542 Ga):

Rodinia breaks apart at about 800-750 Ma.  A short-lived supercontinent reforms (Pannotia) at about 650-600 Ma.

In Grand Canyon, a rift-related marine basin records Rodinia break up=  Chuar Group!

Sedimentary record:  
glacial deposits widespread (~750-635, a less severe on at about 580 Ma), some associated with cap carbonates, poorly dated, some show signs of deposition in low latitudes.  Could there have been a snowball Earth?  or several episodes?  One cap carbonate dates to 635 Ma in several places on the planet--suggesting an alkalinity event (and is used as base of Ediacaran Period).

Reminder for glacial deposit indicators:  striated clasts, bull-nosed clasts, diamictite, striated pavement, dropstones

Life in Neoproterozoic:  becoming more complex...vase-shaped microfossils at 750 Ma--these are testate amoeboe.  they look very similar to modern ta.  these did not photosynthesize.  they hunted....and ate other things (heterotrophs)...and sometimes each other!

Ediacaran fossils--575 Ma, found on many continents, but first in Ediacaran Hills, Australia.  What are these weird impressions? Thought to be the first multicellular organisms--more animal-like than plant-like.  leathery.  found often in coarse-grained sandstone!

Small Shelly Fossils (Cloudina)--548-542ish.  Index fossil for the almost Cambrian (infraCambrian).

Bammo---trace fossils, archeocyaths....you are in the Phanerozoic!

TOPIC 10--ARRIVAL INTO THE PHANEROZOIC--THE PALEOZOIC ERA (542-251 Ma) (graphics)
What makes the Phanerozoic so different?
fossil record--hard parts!  more complete
sedimentary record--more complete (sometimes)
record of ocean floor since Triassic time
more robust (sometimes) geochemical and magnetic records

recall a few things about plate tectonics from chapter 3:  three types of plate margins!

Global-scale changes throughout the Paleozoic--plate tectonic reconstructions...

Laurentia and how it changes through the Paleozoic (coarse scale)--becomes Laurasia!  Pangea!!

Cratonic sequences (e.g., Sauk, Tippecanoe, etc) indicating epeiric seas (widespread shallow seas covering continents)--these are alos know as Sloss sequences--How much time do they represent?  What caused these rises and falls of sea level?

Grand Canyon classic sequence to show a cratonic (Sloss) sequence (Tonto Group--Sauk Sequence)--indicate major transgression onto "western" Laurentia

Laurentia is actually rotated about 90 degrees clockwise in Cambrian time, and slowly, throughout the Paleozoic, rotates counterclockwise almost 90 degrees.

Reefs become important in early-mid Paleozoic time.  What is a reef?  THey can be barriers and form lagoons.

Many orogenies affect the "east" and "south" sides of Laurentia.  These are collectively known as the Appalachian and Ouachita mobile belts, respectively.  So, how do we know these orogenies occurred?  What evidence is there in the rock record?
        --clastic wedge, coarser toward highlands
        --igneous rocks and metamorphic rocks of the same age (and same age as clastic wedge)
        --angular unconformities and deformed rocks showing crosscutting relations and timing of deformation

Recall that throughout most of Paleozoic time, the "west" coast of Laurentia was passive and the "east" coast was active.  The Devonian was a significant time in Laurentian plate tectonics:  The Antler Orogney took place along the "west" side, and the Iapetus Ocean closed on the "east" side, resulting in a continental-continental collision, the death of Laurentia, and teh birth of Laurasia (Laurentia + Baltica (proto-Europe).  This latter collision created HUGE clastic wedges of Devonian age (Old Red Sandstone in Europe, Catskill Fm equivalent in NA).

Because, by late Paleozoic time, there was significant convergence along much of the paleo-Larentian margins, intracratonic deformation occurred--Ancestral Rocky Mountains formed.  It was like a basin-and-range style(?) of tectonics, with uplifted older crystalline basement, and proximal deep basins full of immature sediment.  The Oquirrh basin of Utah was such a basin, and is represented by the Pennsylvanian Oquirrh Fm.

The formation of Pangea marks a good time to review the theory of continental drift and also how we know plates move around (PALEOMAGNETISM).

Evidence for continental drift:
    --fit of continents
    --similarities between Gondwanan flora and fauna
        --Glossopteris flora, Mesosaurus, Lystrosaurus, Cynognathus
    --glacial evidence in Gondwanan continents.
    --mountain ranges match up that are now truncated by continental margins
    --coal deposits in North America coeval with glacial and high-latitude coal deposits of Gondwanan continents
    THIS THEORY WAS NOT ACCEPTED EVEN BY THE 1930s, BECAUSE IT LACKED A MECHANISM...

Paleomagnetism:
Recall Earth's magnetic field (Earth is a big bar magnet)
Magnetic minerals align with magnetic field at time mineral cools above Curie Temperature
Ancient magnetic-mineral-bearing rocks (e.g., basalt) record paleo-magnetic north!
Apparent polar wander--How is this resolved?

Life in the Paleozoic Era:
Cambrian explosion--sudden appearance of new animals (sudden in that they are better preserved with hard parts, not so sudden in that many multicellular organisms has evolved and are preserved in Ediacaran strata).

Why do organisms start making shells?
    --predation
    --chemistry of oceans
    --muscle attachments
    --stimualted by warmer global climate?
    --protection from UV radiation
    --moisture retention
 
Typical Cambrian community:  trilobites, brachiopods, echinoderms, proto-chordates
Atypical Cambrian community:  represented by the Burgess Shale (many of the organisms preserved in this deposit likely represent evolutionary dead ends)

Ordovician--
high acritarch diversity, reef builders are bryozoans and corals, brachiopods, conodonts, graptolites, non-vascular plants evolve,
Huge mass extinction at end of Period, associated with glaciation?

Siluro-Devonian:
Hello vascular plants--gymnosperms, coral reefs galore, armored fish and sharks, oldest amphibians, high sea level, another mass extinction near end Devonian.  glaciation connection?

Carboniferous-Permian--
crinoids galore, seas regressing, fusilinids, oldest reptiles (NEED AMNIOTIC EGG), mass extinction--the biggest of all!  cause unknown...



TOPIC 11--THE MESOZOIC ERA (251-66 Ma) (graphics)
Age of reptiles!
Break up of Pangea!
Global and North American views of plate tectonics
Tethys Sea is a big global climate regulator (keeps poles warmer)
western North America is now the active margin (Cordilleran mobile belt) and eastern North America has become passive.....

Break up of Pangea:
Atlantic Ocean started to open in Triassic time, restricted rift basins along the margins--EVAPORITES
Australia and Antartica finally split and move southward by Cretaceous time
Cretaceous--high rates of seafloor spreading and hence sea-level rise!

Mesozoic climate trends:
Pangea pole-to-pole configuration
Hot and arid in middle of large continents or supercontinents
How are hot, dry, cool, wet climates generated?
What can the rock record tell us about paleoclimate?  Think of some examples...

Mesozoic tectonics and paleogeography:
Cordilleran mobile belt is active throughout Mesozoic and many island arcs are accreted.
By Jurassic, a oceanic-continental convergent margin is set up (Nevadan and Sevier orogenies).  The volcanic chain is represented by the modern SIerran granites, the foreland basin is represented by Jurassic-Cretaceous strata in Interior West, the accretionary prism is represented by the metaseds and metavolcs of the Coast Ranges...

Eastern North America undergoes rifitng to drifting into a passive continental margin.
Rift basins are filled with clastics, evaporites

Jurassic and Cretaceous interior seaways inundating foreland basin areas of NA.  Sea level is very high in Cretaceous!

Stratigraphy of the Colorado Plateau and how it reflects the tectonic and paleogeographic evolution of western NA.

Mesozoic fossil record and life:
The Mesozoic Era is framed by two mass extinction!  The P-Tr and the K-T.  
THere are a lot of familiar organisms from the Paleozoic that are gone and left niches open.  Examples:  trilobites, rugosan and tabulate corals, armoured fish..
Invertebrates and phytoplankton:
    --cephalopods abounds--especially ammonites (great index fossils for this era)
    --bivalves (take trilobite niches)
    --gastropods
    --new corals (scleractinians)
    --forams (also great index fossils)
    --photosynthesizers--coccolithophorids (make chalk!), diatoms (make diatomite), dianoflagellates (organic walled)
Plants:
    --gymnosperms doing well, angiosperms arise in Cretacsous and takeover (why?)
Vertebrates:
    --sharks and bony fish (especiall the latter(
    --the reptiles--stem from Mississippian, one lineage gave rise to crocs, flying reptiles, dinosaurs, birds (amniotic egg, upright        
        posture, teeth in individual sockets)

Dinosaurs!  lived for 185 Mys!  Well adapted, diverse, widespread, active, warmblooded?, cared for young
    --bird-hipped (e.g., ankylosaurs, stegosaurs, triceratops, duck-billed)
    --lizard-hipped--theropods (e.g., Tyranosaurus) and sauropods (biggies with long necks, herbivores)
    --warm blooded?  not conclusive.  not all were, and some were maybe both (at different times in life)

Flying reptiles:  pterosaurs, evolution of flight
Marine reptiles:  icthyosaurs, plesiosaurs, mososaurs
Terrestrial reptiles: turtles, lizards, snakes

Archeopteryx--important transitional fossil, contains both bird and reptilian features, Jurassic, helped to argue for birds evolving from dinosaurs.

Mammals:  waiting to pounce, small, nice transitional fossil (cynodonts) showing reptilian and mammalian features.

Mesozoic paleobiogeography:
Continents all pretty close til Cretaceous.  In Cretaceous, climate becomes more zoned, less equable.  animal groups become more isolated.

The K-T extinction:
over a cm scale boundary:  90% of terrestrial and marine organisms are casualties.  E.g., ammonites, many bivalves, some planktonic forms, flying reptiles, dinosaurs, marine reptiles
yet many survivors--crocs!  birds!  etc...
main hypothesis is meteorite impact.  evidence:  Chixaclub crater, Ir anomaly, shocked quartz
other possible mechanisms:  climate change, deccan traps (flood basalts)
regardless of cause, it is still hard to demonstate that the extinction was the same time and intensity everywhere....

   



TOPIC 12--THE CENOZOIC ERA (66-0 Ma) (graphics)

Cenozoic timescale:  work in progress--Palegene and Neogene are replacing Tertiary and Quaternary.
Quaternary may be redefined to include part of the Pliocene (based on glacial records of NA).

Special tectonics events:
Himalayan-Alpine orogenesis
Pacific Ring of Fire subduction
Asymmetric rifting in Pacific, symmetric rifting in Atlantic
Rifting in east Africa
Laramide Orogeny followed by Basin and Range in western NA.

Special volcanic events: (more graphics)
Many throughout Cenozoic in western NA
Yellowstone hotspot--3 big eruptions between 2 and .6 Mya--Huckleberyy Ridge--largest known eruption on Earth!  Still active caldera, how do we know?

Special climatic events: (more graphics)
Overall cooler since Miocene globally
North hemisphere glaciation--30% of conts covered in ice
PETM--Paleocene-Eocene Thermal Maximum

Life in the Cenozoic Era: (more graphics)
marine mammals decended from terrestrial mammals
horses got bigger and had fewer toes, went from browser to grazer in tempo with grass evolution
mammoths, huge kangaroos and beaver and sloth, lots of big things...
Pleistocene extinction--due to climate change?  human overkill?






STUDY TIPS FOR FINAL EXAM:
Read through your old tests (and take an extra copy of Exam 3)
Read through your old study guides
Read through your old labs
Emphasis will be on general knowledge of fundamental geologic terms and concepts, including rock and fossil identification and interpretation

    



















cool links

Periodic chart:  http://www.lenntech.com/periodic-chart.htm?gclid=CKGlmOjY7pACFScViQodRwt74Q
Earth's inner core!  http://www.hno.harvard.edu/gazette/1996/08.15/PuttingaNewSpin.html
Paul Heller' page of sedimentary transport movies:  http://faculty.gg.uwyo.edu/heller/sed_video_downloads.htm
Christopher Scotese's page of plate tectonic evolution movies:  http://www.scotese.com/
Tanya Atwater's geology "visualization" page:  http://emvc.geol.ucsb.edu/downloads.php
blue whale video:  http://www.youtube.com/watch?v=8YtC-VagE4Y&NR=1