Lecture 17 - History of the Earth Flashcards
The history of the earth is recorded in its __________
strata
What is the principle of superposition?
“In a sequence of layered rocks, any layer is older than the layer next above it.”
Who is Nicholas Steno?
Principle of Superposition
What are 2 exceptions to superposition?
- intrusions
- overturned rock
What are plate tectonics?
movements of the earth
Layers are originally deposited _________
horizontally
What alters the the orientation of the layers?
plate tectonics
What is uniformitarianism?
-processes that alter the Earth are uniform through time
Who was Charles Lyell?
- believed in uniformitarianism
- earth was transformed not by unimaginable catastrophes by slow changes
What are 4 processes that result in the production of sediment particles?
- erosion
- volcanic eruption
- organisms
- mineral precipitation
What are 4 conditions that make it more likely that an organism will have fossil record?
- has hard parts
- is abundant and widespread
- exists for a long time
- lives in a habitat conducive deposition
How are rocks and fossils dated?
biostratigraphy
Sedimentary strata only reveals __________ ages
relative
how can absolute dating in igneous strata be determined?
radiometric dating
a “parent” isotope decays into a “daughter isotope at _________
a constant rate
What is a half-life?
time required for half the parent isotope to decay
What is the believed age of the earth?
4.6 billion years ago
What is most atmospheric origin?
biological origin
What produced this biological origin?
photosynthesis in bacteria similar to modern cyanobacteria
What did O2 reacted with?
dissolve iron
What did the O2 and dissolved iron do?
precipitated out to form banded iron formations
What did the O2 revolution cause?
- enormous die-off of many organisms
- anaerobic organisms had to either hide or adapt
What are 3 qualities of the earliest eukaryotes?
- from about 2.1 BYA
- probably spherical algal protists
- probably formed by endosymbiosis
What are 3 qualities of terrestrial plants?
- primitive vascular system
- waterproof coating
- mycorrhizal fungi
What are 2 qualities of earliest terrestrial animals?
- possibly arthropods
2. included organisms similar to modern millipedes etc.
What is the Principle of Superposition?
in a sequence of layered rocks, any layer is older than the layer next/above it
What happened 3.8 BYA?
oldest rocks on earth’s surface
What happened 3.7 BYA?
oldest fossils of cells appear (stromatolites)
What are stromatolites composed of?
- bacteria
- sediment biofilm
What happened 2.7 BYA?
concentration of atmospheric oxygen
What happened 2.1 BYA?
oldest fossils of eukaryotic cells apear
How were the oldest fossils of eukaryotic cells formed? What were they?
endosymbiosis
spherical algal protists
What is the Theory of Serial Endosymbiosis?
- large host cell and ingest bacteria could easily become dependent on one another for survival
- permanent relationship
What happened 635 MYA?
Ediacaran
What was the Ediacaran age?
- diverse algae
- soft body invertebrate animals appear
What happened 540 MYA?
Cambrian Explosion
What was the Cambrian Explosion?
- resulted in modern body plans
- hardbody forms
- movement from seafloor to new niches
What was the reason for the explosion in diversity? Theories?
- unknown
- theories: increase O2 availability, mineral availability, evolutionary innovation
What happened 488 MYA?
marine algae abundant
-colonization of land by diverse fungi, plants, animals
