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170 Cards in this Set

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  • Back
What was the theory of Geosynclines first used to account for?
It was one of the early-mountain building theories
What is a geosyncline?
A geosyncline is a largely obsolete term for a subsiding linear trough that was caused by the accumulation of sedimentary rock strata deposited in a basin and subsequently compressed, deformed, and uplifted into a mountain range, with attendant volcanism and plutonism. The filling of a geosyncline with tons of sediment is accompanied in the late stages of deposition by folding, crumpling, and faulting of the deposits. Intrusion of crystalline igneous rock and regional uplift along the axis of the trough generally complete the history of a particular geosyncline. It is then transformed into a belt of folded mountains. Thick volcanic sequences, together with graywackes (sandstones rich in rock fragments with a muddy matrix), cherts, and various sediments reflecting deepwater deposition or processes, are deposited in eugeosynclines, the outer deepwater segment of geosynclines.
What are the two types of Geosynclines?
1) Miogeosynclines
2) Eugeosynclines
What is the difference between a miogeosyncline and a eugeosyncline?
A Miogeosyncline develops along the continental margin on the continental crust. They have lithologies that correspond with shallow marine sediments (Graywackes and cherts)

Eugeosynclines have lithologies that correspond with deep marine sediments
What is the large scale breccia formed near the accretionary wedge in an ocean-continent orogenesis (near the eugeosyncline)?
What kinds of deep and shallow sediments, respectively, will one find as a mountain erodes in an ocean-continent orogeny?
Deep Sediments = Flysch
Shallow Sediments = Molasse
What is a decollement?
A décollement horizon is a tectonic surface that acts as a gliding plane between two masses in a thrust fault relationship
What is a foredeep?
It is a big basin in which sediment is deposited.
Who was the first to provide an idea of what constituted a species?
Buffon - he bounded species as animals that could not interbreed with other species

He also asserted that animals are closely related
Who was the first to start mentioning some of the forces that drive evolution?
Erasmus Darwin
What are some of the forces that Erasmus Darwin linked to evolution?
1)Sexual Selection
2) Food gathering
3) Security
What primitive mechanism did Erasmus Darwin envision for his ideas of evolution?
New characteristics are acquired so that an animal fits in a new environment and these characteristics are passed on
Who was next in the lineage of evolutionary thought after Erasmus Darwin?
What did Lamarck believe about the inheritance of acquired traits?
He believed that a change in environment leads to a change in needs which leads to a change in habits which leads to a change in characteristics which leads to new speices
What other facets distinguish Lamarck's conceptualization of evolution?
1) Animals have built-in drive for "perfection"

2) Organisms have the capacity to be adapted to their environment

3) Spontaneous Generation
Who was Charles Darwin?
The father of modern evolutionary thought
What was the name of the ship Charles Darwin was on and for what years was he on it?
The HMS Beagle from 1831-1835
What did Charles Darwin do on his voyage pertaining to his later theory?
1) He noted the rich diversity of life he observed

2) He came to believe that along with environmental change, only the fittest for that particular environment survived, as opposed to Lamarckian thought which was that organisms could change to their environments impromptu
What is a summary of Charles Darwin's conceptualization of Evolutionary theory?
1) The World is not static - species change, new ones form, old ones go extinct

2) Evolution is gradual

3) Natural Selection is the mechanism
Struggle for Survival => Reproductive success is key
What is a Phylogeny and what is an Ontogeny?
Phlogeny = How species change over time

Ontogeny = The development of one species over its lifetime
Who is Haeckel and what did he do?
He is a dude in the 1800's that is famous for his "Ontogeny recapitulates phylogeny" theory
What did Haeckel believe evolution does?
He believed it simply added stages at the end of life
What is orthogenesis?
The idea that evolution functions by an intrinsic drive towards perfection; natural selection unimportant. Characters produced may be totally non-adaptive, i.e. have no survival value.
How does orthogenesis procede?
In a striahgt, linear fashion

A=>B=>C=>D=>ad infinitum=>(Perfection)
What is the synthetic theory of evolution?
It is the same as NeoDarwinism and basically is that evolution is gene based and that it is the survival of the fittest genes, increasing the frequency of those alleles whose phenotypic effects promote survival.
What are the changes in DNA due to, and how frequently do these changes occur?
The changes in DNA are due to mutations.

They occur 1 to 8 times per 100,000
What does natural selection do?
It eliminates non-adaptive characters and pressures adaptive ones
What was the consequence for the Lamarckian theory of evolution after the Synthetic theory of evolution gained steam?
Larmakian evolution was no longer beleived; the inheritance of acquired genes was shown to be incompatible; the acquisition of genes came through random mutation, not through habit
The theory of Synthetic evolution is characterized by what attributes?
1) Gradual evolution
2) Natural selection
3) Genetic variability - recombination, mutation, chance events
4) Interbreeding populations and into species - gene pool
What is a genotype?
The actual full complement of genes that the individual has
What is the phenotype?
It is the physical expression of those genes, and it is also dependent on environmental conditions - Genotype + Environment= Phenotype
What causes genes to change?
What two kinds of genes is DNA composed of?
1) Structural genes
2) Nonstructural genes
What do structural genes do?
They code for all the things in your body
What do nonstructural genes do?
They turn structural genes on and off
What are point mutations of chromosomes?
A point mutation, or substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide. Often the term point mutation also includes insertions or deletions of a single base pair (which have more of an adverse effect on the synthesized protein due to nucleotides still being read in triplets, but in different frames- a mutation called a frameshift mutation). For coding sequences one can categorize such point mutations as follows:

* nonsense mutations: code for a stop, which can truncate the protein.
* missense mutations: code for a different amino acid.
* silent mutations: code for the same amino acid.

For example , sickle-cell disease is caused by a single point mutation (a missense mutation) in the beta hemoglobin gene that converts a GAG codon into GTG, which encodes the amino acid valine rather than glutamic acid.

Point mutations that occur in non-coding sequences are most often without consequences, although there are exceptions. If the mutated base pair is in the promoter sequence of a gene, then the expression of the gene may change. Also, if the mutation occurs in the splicing seat of an intron, then this may interfere with correct splicing of the transcribed pre-mRNA.
What are chromosomal mutations?
Mutations may involve whole chunks of chromosome, rather than single bases.

A length of chromosome may be translocated to another place on the chromosome, or be inverted. Whole chromosomes may fuse, as has happened in primate evolution; chimpanzees and gorillas have 24 pairs of chromosomes whereas humans have 23. In other cases, some or all of the chromosomes may have been duplicated.

It is more difficult to generalize about the phenotypic effects of these chromosomal mutations. If the break-points of the mutation divide a protein, that protein will be lost in the mutant organism. But if the break is between proteins, any effect will depend on whether the expression of a gene depends on its position in the genome.

In theory, it might not matter whether a protein is transcribed from one chromosome or another; though in practice gene expression is probably at least partly regulated by relations between neighboring genes and a chromosomal mutation will then have phenotypic consequences.
What is the precise definition of a species for this class?
A Species is an array of populations which are actually or potentially interbreeding and which are reproductively isolated from other such arrays under natural conditions
What are the two kinds of populations?
1) Allopatric
2) Sympatric
Species must work to maintain _________?
What is Speciation?
The evolutionary process of species formation
What is the definition of sympatric speciation?
The splitting of lineages whereas phyletic (allopatric) speciation is evolution w/in an established lineage
How do Genotype and Environment interact to produce a Phenotype?
Genetic mutation combined with natural selective pressures from the environment will determine what phenotype is prevalent
What do environental changes cause to develop?
New niches
What is the substance of the constant-environment-stability-time hypothesis?
1) Generalist organisms have broad tolerance due to changing environment; therefore, they have low diversity because there is no selective pressure
2) Constant environment will cause higher levels of diversity; animals specialized to microniches so there is less competition among them
What is Phyletic Gradualism?
*Sympatric Speciation*

It is speciation that occurs in the absence of geographic isolation; it occurs through very slow, gradual change
What is Geographic Speciation - Punctual Equilibrium?
* Allopatric speciation *

Divergence from parent stock
The local populations are geographically isolated from one another => different environmental pressures => different species formed (more like subspecies)
What are polytypic and monotypic species?
Polytypic = Species has 2 or more subspecies

Monotypic = Species w/o subspecies
Why is recognition of polytypic species important for scientists?
It simplifies classification
What are sibling species?
Corliss's description = reproductively isolated w/ little morphological differences

Wikipedia = cryptic species complex is a group of species that satisfy the scientific definition of species — that is, they are reproductively isolated from each other — but which are not morphologically distinguishable. The individual species within the complex can only be separated using non-morphological data, such as from DNA sequence analysis, bioacoustics, or thorough life history studies. They can, but need not be, parapatric, quite often are sympatric, and sometimes allopatric.
What is a cline?
In population genetics, a cline is a gradual change of a character or feature (phenotype) in a species over a geographical area, often as a result of environmental heterogeneity. The change in phenotype does not result in different species as long as the geographically spread populations can interbreed with one another. This meaning of cline was introduced by Sir Julian Huxley.
What are subspecies?
Subspecies are geographically isolated populations that result from allopatric speciation. They are not units of evoltion (they can still reproduce together but they are not perpetuated).
What is a trinomen???
, or trinominal name, refers to the name of a subspecies.

A trinomen is a name consisting of three names: generic name, specific name and subspecific name. All three names are typeset in italics, and only the generic name is capitalised. No indicator of rank is included: in zoology, subspecies is the only rank below that of species.

Buteo jamaicensis borealis is one of the subspecies of the red-tailed hawk. (Buteo jamaicensis).
What are the three components of a trinomen?
What are the Other terms we need to know regarding speciation?
1) Ring Species
2) Founder Effect
What is a ring species?
In the case where the cline bends around, populations next to each other on the cline can interbreed, but at the point that the beginning meets the end again, the genetic differences that have accumulated along the cline are great enough to prevent interbreeding (represented by the gap between pink and green on the diagram). The interbreeding populations in this circular breeding group are then collectively referred to as a ring species.
What is the Founder Effect?
The founder effect was defined by Ernst Mayr in 1963 to be the effect of establishing a new population by a small number of individuals, carrying only a small fraction of the original population's genetic variation. As a result, the new population may be distinctively different, both genetically and phenotypically, from the parent population from which it is derived. In extreme cases the founder effect is thought to lead to the speciation and subsequent evolution of new species. The founder effect is a feature that can also occur in memetic evolution.

Corliss's Explanation= Different from allopatric subspecies because in a transition of specis from A=>B, in allopatric speciation, B is a random subspecies, whereas with founder's effect, the B must have first separated themselves due to a slight difference
What are the two main factors of Natural Selection?
1) Generation time
2) Rate of evolution - should be proportional to variability
What are some generalizations about evolutionary rates?
1) Evolution rapid in large populations that are subdivided
2) Well-established species evolve slowly
What are some biological methods of species discrimination?
A) Morphology, physiology, behavior, ecology
B) Amounts of A between species is reasonably constant within a group
C) Phenotypic change- and assume two species cannot live sympatrically without being different species
What does geological separation cause speciation?
*Bad Question, but the notes are weird in this part*

1)The morphology between ancient and modern species is different
2) Most species are distinct => Long isolations lead to big differences
Division of Lineage => How subjective is species designation?
It's pretty subjective; There is a diagram of 1=>2=> 3 and 4 via different branches. Do we separate the species exactly at fork, or do we do it above the fork, or is the fork really just one species continuing with another branching off, therefore making it 3 species instead of 4?
What are chronospecies?
A chronospecies is a species which changes physically, morphologically, genetically, and/or behaviorally over time on an evolutionary scale such that the originating species and the species it becomes could not be classified as the same species had they existed at the same point in time. Throughout this change, there is only one species in the lineage living at any point in time, as opposed to cases where one species branches off into many through divergent evolution.
Review => What is the difference between Allopatric speciation and Phyletic Gradualism ?
Allopatric Speciation = Punctuated Equilibrium (sudden appearance)

Phyletic Evolution = Continuous Change
What is adaptive radiation?
Many new taxa come in a short period => a large burst of evolution
What is mass extinction?
Short interval of time in which many species go extinct
What often happens after a Mass Extinction?
Adaptive Radiation => After a mass extinction, many new niches open up
Who was the father of modern Taxonomy?
Carolus Linnaeus
When did Carolus Linnaeus live?
What is classification of organisms based on?
1) Phylogeny
2) Morphology
What are the names of the categories of the classification of organisms?

King Phillip Can Only Find Green Slippers
What is a precambrian shield and where are they?
It is a vast area or areas of exposed ancient rocks that are found on all continents
What are platforms?
Platforms are the areas of the continent that expand out from the precambrian shields and contain buried ancient rocks
What is a craton?
Together, the precambrian shield and its platform make up a craton
What three main categories of Finches did Darwin observe?
1)Ground Finches
2) Tree Finches
3) Warbler-like Finches
What was the significance of Darwin's finches?
he showed that there were multiple species of the same bird that had evolved to the environments based on the weather, geography and diet. They differed only in the size of their beaks.
Why was the Pre-Paleozoic and Archean phases of Earth history particularly economically important?
1) Iron-ore=> Formed banded iron deposits
2) Gold, silver, copper, nickel, chromium, uranium
3) 1/2 of the metallic minerals we find were from this period
What is the timescale for these periods of earth history and what is it based on?
Archean = 3.8=>2.5 byo
Proterozoic = 2.5=>0.54 byo

Based on Isotope Dating from the Great Lakes and Scandinavia
How much of the precambrian shield rocks are exposed on the surface?
Less than 20%
What are "Cratons" ?
The stable parts of the continents that are surrounded by mobile tectonic belts
What happens to the Precambrian shields over time?
They grew by the addition of material over the margin; by accretion at the margin

It began as a small bit of continental material that grew as it was involved in more and more collisions
What is the shield in North America that we are interested in?
The Canadian Shield
What four categories can the Canadian shield be subdivided into based on structure and lithology?
1) Structure
2) Lithology
3) Minerals
4) Age

There are pattersn in the geology based on these characteristics
What two main groups can the Canadian Shield rocks be subdivided into?
1) Granulates
2) Green Stone belts
What are granulates?
They are high-grade metamorphic rocks

They contain little environmental information (because they are so metamorphosed) and if you look and one and the other they kind of look the same and don't give you much info
What are Green Stone Belts?
What is a common mineral in Green Stone Belts (the one that makes them green)?
They are metamorphosed rocks and volcanics with sediments.

Green chlorite
What is the main point about these "Green Stone Belts"?
They are small blocks or features that developed during this time as opposed to large continents.

*Think of small blocks with subduction under each one that creates all of these backyard basins."
Are Green Stone Belts being presently formed?
What were the Green stone belts like?
We must likely have the presence of basins flanked by volcanoes and small steep-sided blocks of felsic crust

Small "mini-continents" that are spread out among the globe

We also have the presence of banded iron formation in these sequences
These are a source of iron ore.
Iron-rich layers alternating with quartz layers

The chert, or the quartz, is precipitated from seawater

These probably tell us about the chemistry of the seawater in the old Archean rocks
How common were Non-marine and Continental Shelf deposits during the Archean?
Rare. Most archean sedimenst are deep water.

Shallow water sediments are quite rare

Terrestrial and fresh water deposits are unknown

There were NO large continents
Tell me about Archean Tectonics.
There were Cratons

Cratons at that time = small, steep-sided, felsic protocontinents, separated by numerous basins that accumulate lava and volcanic sediments to form a greenstone belt
What major geological formation was finally formed at the end of the Archean? How old is one of the oldest and where is it located?
Cratons; occurred in late archean. On some of the oldest cratons, like South Africa, you'll find rocks that are 3.6 billions years old
What was the stability of the crust like during the archean and why?
It was very unstable becaue of all the heat and volcanic activity occurring.
What is one the big differences between the Proterozoic and the Archean?
The proterozoic has broad shallow seas that existed
What does it take to develop a continental margin?
It takes a lot of erosion to pile thousands of feet of sediments to build that margin at the edge of the continent.
What happens to cratons when orogenies take place?
Craton Growth- The suturing of microplates, associated with a lot of igneous activity
What where the four intervals over which Laventia was formed?
1)Kenorian Orogeny => 2.5 bya
2) Hudsonian Orogeny => 1.7 bya
3) Elsonian Orogeny => 1.4 bya
4) Grenvillian => 1.0 bya
What do each of the four intervals during the North American supercontinent formation also correspond with?
They also correspond with provinces => ancient zones of orogenic activity
Why does the geology get complicated with these orogenies?
Multiple events are occurring, the collision of microcontinents at different places and different times
What was involved in the Kenorian Orogeny?
The Kenoran appeared to have united many small Archean blocks into a large stable craton
What happened during the Elsonian orogeny?
Most of the Canadian Shield had been accumulated
What happened during the Grenvillian orogeny? And when did this occur?
A new event; the craton being formed BROKE APART. In other words, rifting occurred.

This happened from 1.0-1.3 bya
It is referred to as the mid-continental rift. Thus, there is actually spreading in Larentia (a spreading center existed) along with faulting and igeneous rocks being produced
What kinds of igneous rocks were produced during the Mid-Continental rifting in the Grenvillian interval?
1) Lava
2) Keweenawan basalts
What ultimately happens to the rift that formed during the Grenvillian interval?
The rifting ceased and the continent stops breaking and becomes stable. Thus, it its an example of a FAILED rift.
Where were some of the Grenville rocks deposited in the USA?
In New York, the Blue Ridge Mountains, and other areas near the Appalachians

These are some of the oldest rocks in the USA
In North America, what kind of deposits were found in the western United States and what did they provide possible evidence for?
They found sedimentary deposits that are locally preserved from 1.4-1.5 bya.

They may be evidence that some rifting occurred in western parts of North America as well, which might be slightly older than the eastern continental rifting
What is Rodinia? What time was it asssembled? When did it split apart?
It is the larger supercontinent which the grenville and previous orogenic events are thought to be part of which was thought to have been assembled by 1 billion years ago

It split apart about 800-700 mya
What is the Pan-African Orogeny and when did it occur?
It is another supercontinent that was thought to have possibly come together after the split that occurred
When did the first evidence of large scale glaciers occur?
During the Proterozoic period.
How long ago was the Gowganda formation and what is it?
It was about 2 bya, and there is evidence of extensive glaciation

They had well-laminated mudstones = "varves"

Sediment deposits during the warm part, and then the clay solidifies during the cold period, so you get these really well-layered varves
When was the Late Proterozoic glaciation?
It was 800-850 mya

This was the time that people popuplarly refer to as "Snowball Earth"

It is thought that the entire earth was glaciated at that time
What are tillites and tills?
They are deposits left by glaciers
What do the ages of the glaciation during the Proterozoic range from?
They range from 1bya to about 600mya.

It is thought that there were several episodes of glaciation
What started to appear during the Proterozoic that wasn't in the Archean (geological stuff)?
1) Large Cratons
2) Sediments => lots of quartz sands formed, which implies a lot of weathering (which didn't occur during the Archean)
What evidence do we have in proterozoic rocks regarding atmospheric oxygen?
There are examples of unoxidized carbon in sulfur minerals in the Precambrian => This means that there was not abundant oxygen at the time

Also pyrite and uranium would be unstable in the presence of oxygen and these are found in rocks older than 2 billion years
What are iron-banded formations and why are they significant? About what time did they show that _______ levels were high?
1) Really colorful white and reddish (dark colored rocks)
2) The iron here is at least weakly oxidized
3) Indicates that some oxygen is present
4) The Oxygen is thought to be relatively high by about 2.0 bya
What was the first signs of PreC life?
Primitive Bacteria and Blue-Green Algae (Cyanobacteria)

1) These are the only life that is present in Archean rocks
2) These are prokaryotic celss
3) They lack a nucleus and internal organelles
4) DNA is not clustered into chromosomes
What are two main ideas regarding how these early cells developed?
1) Lived in an environment filled with nutrients (nutrient broth in a shallow environment)
2) Perhaps new-life formed at mid-ocean ridges (hot water, rich in dissolved compounds)
Where did the Eukaryotes come from?
They evolved from the Prokaryotes.
What is the difference between prokaryotes and eukaryotes?
1) They have chromosomes and organelles and are generally larger
2) In general, they are about 60um or larger whereas prokaryotes are around 20um or smaller
How do people think prokaryotes developed?
1) One prokaryotes consumed another one and the one inside became the mitochondria and thus they became a eukaryote
What is one common fossils that is a super important part of our information regarding early life?
The Stromatolite
-They are some of the earliest evidence of life
These things are basically structures with layers of carbonate sediments which are rich in organic matter alternating with carbonates

Its not an actual organism, it is the sediments that are left by cyanobacteria

It looks like a toadstool with the cyanobacteria growing on top and they make the organic material and the carbonates land on top too
What are the characteristics of Stromatolites?
1)They have banded cabbage-like structures rich in organic matter
2) They are formed by B-G algae which lays down the organic matter
3) CaCO3 trapping occurs
4) Stromatolites can be supersmall (just microns) and up to tens of meters as well
What is the oldest stromatolites that have been found and where?
3.4-3.5 bya in Australia

That being said, Archean stromatolites are present but rare.

They are important however, because they represent the presence of blue-green algae
What is the Fig Tree Formation?
And when did it occur?

-It is a formation caused by blue-green algae that occurred about 3 billion years ago
-There are filaments of organic carbon suggesting that there was primitive but vigorous microscopic life at the time
About what time did Stromatolites start becoming abundant?
About 2.3-2.2 bya
What are the Gunflint fossils (ALSO ON TEST!!)? How many species of BG Algae where in them?
They are direct evidence of the life found at 1.9bya. They are a black chert in a banded iron formation near Lake Superior. Here we have on the order of 12 species of Blue-Greens
What are three formations that had eukaryotes and when did they occur?
1) Neggunee Fron Formation => 2.1 bya

2) Beck Springs Dolomote => 1.3 bya

3) Bitter Springs Formaiton, Australia =>0.9-1.0 bya

4) Acritarchs => Plankton =>1.4 bya
What time span was the Eocambrian Period?
From 540-100 mya
What were the characteristics of the Eocambrian period?
1) Evolution occurred
2) Eukaryotes=> colonies, specialized cells arose
When did the Ediacara fauna exist?
670-545 mya
What are some examples of Ediacara fauna?
1) 1947 in Austrailia they found Pound Quartz

2) Impressions of jellyfish, corals, worms and echinoderms found
What are some of the significant things about the Ediacara fauna?
1) The first glimpse we have of our ancestors?
2) Highly unusual occurrence => shows that life back then was more diverse than we thought
3) There are no skeletons from this period
Give me a summary of the dates of life in the Eocambrian
Eukaryotes => 2 bya
Trace Fossils => <1 bya
Multicellular organisms = <1 bya
What time period was the tommotion stage?
530 million years ago and lasted for about 3 million years
What was the most significant thing about the tommotian stage?
It had the acquisition of skeletons!!
Where was the Burgess Shale Fauna found?
Field, British Columbia - Middle Cambrian
Who discovered the Burgess Shale fauna?
Charles Walcott in 1909,1910
What level of diversity of species was found in the Burgess Shale?
>120 species
The Largest Diversity of fossils yet
They were unusually well-preserved; even had some soft parts
What environment were the fossils in the Burgess Shale preserved in?
They were at the base of reefs; there was turbidity current; There were anaerobic conditions; They were buried at all angles
What were the characteristics of the assemblage of the fossils?
1) They were 20% trilobytes, brachiopods echinoderms
2) Antropods, prifera, coelenterates, mollusks, annelids, chordates
What was there a sudden radiation of at the end of the ediacaran fauna?
There was a sudden metazoan (animalian) radiation following the Ediacaran fauna
What major extinctions occurred in the Cambrian?
Trilobytes and Nautiloids
Why did Trilobytes and Nautiloids go extinct?
-Sudden sea level change doesn't occur
-Sudden cooling => perhaps the cause
What are some characteristics of Ordovician life?
1)Trilobyes => not as diverse (they are going out)
2) Brachiopods - Expansion
3) Graptolites
6) Vertebrates
7) Corals
8) Echinoderms
9) Colonial animals
Tell me about Graptolites.
1) They were common in the Ordovician and Silurian
2)They are found in black shales
3) They are good index fossisl
4) They are from planktonic orkanisms
Tell me bout Conodonts.
They were worm-like animals
They had a broad distribution
What happened to the mollusks?
1) Nautiloids=> expansion
2) Cephalopods=> 6m long; they were large predators (Giant Squid)
3) Bivalves did well
What about Vertebrates?
1) Jawless Fish did good
2) Predators = starfish, nautiloids
How about Corals?
1) Ragose Corals (horn corals); Prominent during this period, almost always made casts becuase it would get filled with stuff
What about EChinoderms?
1) Crinoids very important (sea lillies)
2) Sea urchins too
What kind of Colonial Animals were around in the Ordovician?
1) Bryazoa = ???
a)Stromatoparoides = ???
b)Tabulate Corals=> "Honeycomb corals"
What are Archeocyathids?
Reefs that look like hollowed out horn corals that are sponge-like in nature
How big could the tabulate corals get in the Ordovician?
100 meters across, 6.7 meters high
What was happening with the Stromatolites during this whole Cambrian=> Ordovician switch?
They were abundant at the end of the Cambrian and at the beginning of the Ordovician

They declining sharply by the end of the Ordovician
What happened at the End of the Ordovician?
There was a terminal mass extinction event; 1/2 of the brachiopods and bryozoans died out in N. America
-Coincided with sea level change and global cooling
What was the sealevel like in the Cambrian and then throughout the Ordovician?
The sealevel rose during the Cambrian so that the craton kept getting smaller and smaller as the sea rose

At the beginning of the Ordovician the sea level was high; it regressed a big at the end of the early Ordovician, but then it stayed high after that.
What kinds of sediments were deposited during the Ordovician?
1) CaCO3 was predominate
2) Oolites are common
-They are small spheres of CaCO3
What are Oolites?
Small spheres of CaCO3
Where are Oolites found and how do they form?
They are found in the Grand Baham banks, and they are accretionarily formed over time in shallow water as a small bit of shell or something aggregates layers of CaCO3
What is Central Laurasia like during Ordovician?
1) The area is exposed
2) there is well-sorted sandstone => called St. Peter's sandstone; many pure quartz crystals, sandstone indicates reworking, erosion (sea level regression)
Tell me about the progression of Appalachian Tectonic Activity.
1) During Precambrian= only siliciclastics stuff
2) Early Cambrian/ Cambrian = Trangression of sea and CaCO3 becoming prominent again with the rising sea level
3) Mid-Ordovician => CaCO3 increases; flysch deposits occur
What is the name of the formation that is made of organic rich darker sediments - flysch - that we are going to visit on our fieldtrip?
Martinsburg formation
What does the Martinsburg formationn have?
1) Black Shales
2) Turbidites
When did Mountain Building begin?
the Middle Ordovician
What is the Taconic Orogeny and when did it begin?
It is the first phase of the Appalachain mountain building and it began middle-late ordovician
What happens to the flysch at the end of the ordovician (deep water)?
It turns into molasse (sandstone, shale, shallow water)as foredeep fills with mountain eroded sediment
What happens with plate tectonics during the Ordovician?
1) The Iapetus ocean forms and separates Laurentia from Baltica
2) Volcanism produced on land margins due to subduction
Tell me about the paleoclimates during the Cambrian
The early Cambrian had cool conditions
1) cool
2) warming
-many continents (NA,Europe,Antartica) near equator
-The presence of evaporites and limestones at high latitudes (not only equator) indicate a warm climate
What happened with the paleoclimate during the Late Ordovician?
There is evidence for glaciation on Gondwanaland
1) Glacial Deposits in Sahara Desert
c)ice-rafted boulders
2)Gondwana Land (Africa part of)
-Located over South Pole
-Enhanced chance for glaciation but were times w/ land over South pole w/o glaciation