3: Earth History Flashcards
What are original remains?
Organisms that have been ambered in stone.
What is the mnemonic to remember the order of the geological time scale?
Cold Oysters Seldom Develop Many Precious Pearls, Their Juice Conceal Too Quickly
What is angular disconformity?
When new rock deposits on top of an old rock that has been tilted. Where the old jagged rock and the new horizontal rock join, this is called the angular disconformity.
What is the principle of original continuity?
When rocks are separated by a large basin, even though there is a large gap between layers, they are still the same layer.
What is an epoch?
Smallest divide of time in comparison to others (i.e.: Era/Period, etc)
What is the principle of succession?
When forming rocks, they form one on top of another with the eldest at the bottom and the youngest at the top.
What does mya mean?
A million years before the present time.
What is a classic example of a place where the rocks may have taken a million years to develop?
Grand Canyon
What are the key points of an angular disconformity?
- The old rock is not horizontal, it is jagged
- The new rock forms in parallel and horizontal layers.
What are the 5 steps to relative dating?
- Principle of Superposition
- Principles of Original Horizontality
- Principle of Cross Cutting
- Principle of Original Continuity
- Principle of Faunal Succession
What are the 4 eons the geological time scale is separated into?
Precambrian, Paleozoic, Mesozoic, and Cenozoic.
What are the name(s) of the eons?
Proterozoic Era, Mesozoic Era, Cenozoic Era (current era)
What are casts and molds?
These are usually caused by organisms that have hard shells or the like. The underlayer is usually very soft, so when the shell or the bones sit on top, they create a mold. Then, the soil hardens giving time for the shell to disintegrate. It will then be filled with minerals, and the like.
What is an eon?
A large period of time where there was a mass extinction
What are the 3 stages that are under precambrian?
Hadean, Archean, and Proterozoic
How long ago was the Earth created?
4.55 billion years ago
What is catastrophism?
The thought that everything on Earth was created by some supernatural force of power.
What does the mnemonic stand for?
Cambrian, Ordovician, Silurian, Devonian, Mississipian, Pennsylvanian, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary
Why do varves occur more often in freshwater lakes than saltwater lakes?
Saltwater Lakes tend to cause a homogenous mixture of the substance (uniform).
What happens to varves in the summer months?
Water and sediment take up more room. They are usually a lighter colour. The amount of sediment flowing back and forth is relatively large.
What is nonconformity?
When the igneous or the metamorphic rock is exposed to the surface, a new layer of rock forms on top of it. Where the igneous/metamorphic rock meets the new rock, is known as nonconformity.
What are the 5 types of fossils?
- Original Remains
- Casts and Molds
- Carbonization
- Permineralization
- Trace Fossil
What happened during the Cenozoic Era?
Lots of mammals
What are 2 things that eras are separated by?
Time and structure of organisms
What is the principle of cross cutting?
Faults are caused by intrusions or earthquakes. The rock layers that surround this intrusion are older than the fault itself.
What are the key points of nonconformity?
- The contact between new and old rock is formed in parallel layers.
What are varves?
Layers that have deposited in one year. They usually occur in freshwater lakes rather than saltwater lakes.
What happened during the Proterozoic Era?
Happened 248 million years ago with extinction of 90% of Marine Animals
What are the key points of disconformity?
- Disconformity: Boundary between old rock and new rock
- Contact between the old and new rock is an irregular surface
What is disconformity?
The youngest horizontal layers erode, revealing the older layers. New rock is then deposited. Where the old and the new rock join, this is known as disconformity.
What type of thing was very prevalent at the end of the Hadean time?
Bacteria
What happened during the Mesozoic Era?
The Dinosaurs were all killed due to a meteorite impact.
What was Hutton’s evidence?
Geological processes that he witnessed were so complex that it would not be able to form in a short amount of time.
What is one thing that varves may tell us about the temperature of a certain time period?
The thickness of layers can help determine the temperature or the climate of a certain time period. A very thick light coloured layer would then represent a very long and warm summer.
What is the principle of original horizontality?
The Principle of Superposition relies very much on this principe which says that when the Earth’s Crust shifts the different layers, it may look like it is not horizontal. However, when it was first deposited and created, it was.
What are the characteristics for a good fossil?
- Wide Distribution of Fossil
- Fossils are abundant
- Fossil appears in a narrow time span
When did mammals first appear?
Triassic Period
What did William Whewell do?
Claimed Hutton’s observations at “uniformitarianism”.
What is the KT boundary?
The time period in which the dinosaurs roamed the land and the Earth to when there were terrestrial mammals walking about.
What are the three types of unconformities?
- Disconformity
- Angular Disconformity
- Nonconformity
Who suggested that the Earth was much older?
James Hutton
What happens to varves in the winter months?
The flow is reduced significantly because they are all frozen. Also, the particles are usually much darker.
Name 2 epochs:
Either:
- Holocene
- Pleistocene
- Pilocene
- Miocene
- Oligocene
- Ecoene
- Paleocene
What is the principle of faunal succession?
The evolution and extinction of life has produced many different distinct fossils. The age of the rock can help determine the age of fossils. You would only find organisms or fossils that pertain to that time period.
When was cyanobacteria start forming?
Archean and Proterozoic
What are the 5 main pieces of evidence that supports Pangaea?
Perfect puzzle, fossils, fossilized bones, tillite, and mountain ranges.
How can paleoclimates be measured?
Ice, dendroclimatology, and fossils and living organisms.
What is the role of ice in paleoclimatology?
The materials inside the core allow us to estimate the chemical composition at that point in time.
What is the role of dendroclimatology in paleoclimatology?
It is the measuring of tree rings and the age of trees. It can help determine precipitation and many other things.
What is the role of fossils and other organisms in paleoclimatology?
The species can change based on the temperature.
What are the main things that happened during the Precambrian Period?
- Harsher Climate
- Global temperature were much warmer
- “Snowball Earth” at the end of the period.
What are the main things that happened during the Paleozoic Climate?
- Ice sheet covered most of Gondwanaland.
What are the main things that happened during the Mesozoic Era in paloeclimatology?
- Climate stayed relatively warm
- Warmed a lot in the first Cretaceous period
- Temperature differences in poles were very small
- End of Mesosoic Era - cooled down
- Asteroid Impact
- Volcanism
What are the main things that happened during the Cenozoic Era related to paleoclimatology?
- Relatively cool in comparison to the rest of the Earth
- Multiple ice ages in the last 2 mya
- Most of the ice sheets melted 100 000 years ago.
What is the thing that Milankovitch is trying to explain?
Cyclic “rotation” or changing of glaciers.
What are Milankovitch’s 3 main points?
- Eccentricity
- Axial Tilt
- Precession
What is eccentricity?
The Earth’s orbit is not entirely circular, it is often changing between elliptical and circular.
What happens when the earth’s orbit is more circular?
The season conditions in both regions wil be relatively the same.
What happens when the earth’s orbit is more elliptical?
There will be significant differences in temperature (ie: one will have very hot summers and very cold winters while the other will have mild summers and winters).