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OLEMISS / Geology / G E / GEOL 102 / How do we classify organisms?

How do we classify organisms?

How do we classify organisms?


School: University of Mississippi
Department: Geology
Course: Historical Geology
Professor: Janet steeper
Term: Spring 2019
Tags: Geology, Geology 102, Plate Tectonics, nebular, and Theory
Cost: 50
Name: Study Guide For Exam 2
Description: Exam 2 study guide for chapters 5-8
Uploaded: 03/22/2019
8 Pages 60 Views 6 Unlocks

Exam 2 Study Guide

How do we classify organisms?

Chapter 5:


∙ A marine transgression is a geological event during which sea level  rises relative to the land and the shoreline moves towards high ground, resulting in flooding. Transgressions can be caused either by land  sinking or sea level rise  

 Facies move landward because more of the land has been  flooded  

 When are grains are getting smaller


∙ Regression is a geological process occurring when areas of  submerged sea flood are exposed above the sea level. Regression can  be caused either by the land uplift or sea level fall  

 Move seaward  

 When our grains are getting bigger

What is a species?

o Formation: distinctive rock units with recognizable contacts that can  be mapped over a large area  

∙ At any given instant in time, deposition will be occurring in different  environments  

 These various depositional environments are called facies o Facies- is a part of a rock body that has characteristics  from which we can infer the depositional environment  Don't forget about the age old question of Was the pre- wwi era a “golden age”?

o This is all telling us about a depositional environment  

Chapter 6:


∙ The remains or indications of former living things preserved in  rocks or sediment  

∙ The odds that a dead organism or its traces will be preserved are very  low  

What was alfred wallace's theory of evolution?

∙ Conditions on the sea floor commonly favor preservation. Most fossils  are found in marine rocks  

∙ Conditions on land do not favor preservation. Most fossils on land are  found in lake or river rocks  

∙ Most organisms are not preserved. Two special conditions are  necessary for most fossil preservation:

 Rapid burial 

o Means scavengers cannot get to you and eat all your body  parts  

o Be protected so other things can’t degrade you

 The possession of hard parts  

o Helps define what the organism is and what it looks like If you want to learn more check out What characteristics define an animal?

∙ Remains of an actual animal and plant are called BODY FOSSILS- they represent some portion of the actual animal or plant (leaf, bone, shell,  or even an entire animal) Don't forget about the age old question of Characterize burgess shale.

∙ Many different methods of fossil preservation  

Fossil Preservation Types:

∙ Unaltered

∙ Carbonization  

∙ Replacement

∙ Permineralization

∙ Mold and casts


∙ No changes to hard parts (sometime soft parts)

 Ex. Teeth


∙ Soft tissue preserved as thin films of carbon  Don't forget about the age old question of What are some effects of protein deficiency within the body?
Don't forget about the age old question of How is benefit cost ratio calculated?

 Soft tissue gets compressed, compacted and all that remains is a film of carbon  

 Organisms that are already pretty flat and thin  


∙ Simultaneous exchange of the original hard part with mineral matter of another composition  

 Already buried  

 Will dissolve the mineral that’s already there and be replace it  with a new mineral  

 Remove a few atoms and immediately replace it with new atoms  Permineralization  

∙ Minerals precipitate into the open spaces of hard parts 

 The black part is the bone its self & the white part is the mineral  that has filled in the spaces  

Mold and Casts  

∙ Mold: void where the organism’s shell was originally (external imprint) ∙ Cast: infilling of void that shows the shell’s original form  

∙ Sometimes what is preserved is not a BODY FOSSIL, but a TRACE  FOSSIL (evidence of a behavior of life)

 Tracks and trails  

 Borings

 Burrows

 Coprolites

 Gastroliths

What is a Species?

∙ Species are groups of organisms that appear to be identical by  morphological (anatomical) criteria. (Typological concept)Don't forget about the age old question of What is the purpose a break-even analysis?

∙ Species are groups of organisms differ by morphological (anatomical)  criteria from other groups. (Morphological concept)

∙ Species are groups of interbreeding natural population that are  reproductively isolated from other such groups (biological concept) ∙ Species are groups of organisms that share a common ancestor  (Phylogenetic concept)

Theory of Evolution  

∙ Evolution is the continuous genetic adaption of organisms or species to the environment 

∙ The mechanism of evolution and the determination of genetic material  took many years to understand  

Charles Darwin (1809-1882)

∙ Naturalist aboard the H.M.S. Beagle  

∙ Observed geographic distribution of organisms and fossils  ∙ Wrote Origin of Species in 1859 

Alfred Russel Wallace (1823-1913)

∙ Father of Biogeography

∙ Extensive fieldwork in South America (Amazon) and Malay Archipelago  ∙ Independently proposed a theory of natural selection  

∙ Jointly presented paper with Darwin to Linnean Society in 1859 Natural Selection  

∙ From Darwin and Wallace’s Observations they proposed a new  mechanism for evolution:

 Natural Selection: the process whereby organisms better  adapted to their environment ten to survive and produce more  offspring 

Darwin’s Natural Selection  

∙ Natural selection is based on the following observations: 1. More offspring are produced that can survive to maturity 2. Variations exist among the offspring  

3. Offspring must compete with one another for food, habitat, and  mates

4. Offspring with the most favorable characteristics are more likely  to survive to reproduce  

5. Beneficial traits are passed on to the next generation  

Darwin’s Natural Selection  

∙ This principle can be states as: “the survival of the fittest” ∙ Darwin’s theory was unable to explain WHY offspring exhibited  variability.

∙ This was to come many years later, when scientist determined that  genetics is the cause of these variations  

How do we classify organisms?

∙ A system of hierarchical classification of organisms is called Linnean  System  

∙ Taxonomy is the naming and grouping of organisms using the Linnean System

Seismic Waves  

∙ Types of seismic waves

 Body waves travel through Earth’s interior 

1. Primary (P) waves are compression waves  

o Can travel through all materials  

2. Secondary (S) waves are shear waves  

o Can only travel through solid material  

∙ Surface waves travel in rock layers just below Earth’s surface  Body Waves: P waves

∙ P waves are compression waves  

Body Waves: S waves  

∙ S waves are shear waves  

Surface Waves  

∙ Two general directions of motion  

 One causes the ground to move up and down similar to the  movement of ocean swells  

 The second causes the ground to move side to side  

 Causes the greatest destruction

Earth’s Internal Structure  

∙ Crust: Mainly silicate minerals low density rock  

 Oceanic crust  

 Continental crust  

∙ Mantle- 82% of the Earth Volume, high density  

 Composed Mg, Fe silicate minerals  

∙ Core- composed of a very high density of iron-nickel alloy ∙ Lithosphere- the rigid outer layer of Earth that consists of the crust  and the upper mantle  

∙ Asthenosphere- the soft, weak layer below the lithosphere  ∙ Earth’s interior based on physical properties:

 Lower mantle  

 Outer core:

o Liquid  

 Inner core: solid 

From Stationary to Continental Drift  

∙ Up until the late 1960s, most geologists believed the continents and  oceans were fixed in position  

∙ In 1915, Alfred Wegener wrote The Origin of Continents and Oceans,  challenging the stationary continents and oceans  

 Continent Drift Hypothesis

Continental Drift Hypothesis  

∙ A single supercontinent existed in the Mesozoic Era (~200 Million  years)  

 Pangea= “all lands”

∙ In the early Mesozoic Era, Pangea fragments and drift to modern  position  

Evidence for Continental Drift  

∙ Continental Jigsaw puzzle

∙ Fossils  

∙ Rock types and geological features  

∙ Ancient climates  

Plate Tectonics  

∙ Evidence  

 Oceanic crust (age, mid-ocean ridge, trenches)

 Magnetics

 Layers of Earth  

 Wegner’s Evidence  

Plate Tectonics: Layers of Earth  

∙ Lithosphere= rigid, brittle crust plus uppermost mantle ∙ Asthenosphere= partially molten part of upper mantle, below  lithosphere  

∙ Rigid lithospheric plates “float” on flowing asthenosphere  Lithosphere  

∙ Upper part of the lithosphere: Crust types:

1. Oceanic crust: thin, dense, basaltic  

2. Continental crust: thick, lower density, granitic

Type of plate boundaries  

∙ Divergent- the plates move apart from on another. New crust is  generated between the diverging plates  

∙ Convergent- the plates move towards one another and collide. Crust  is destroyed as one plate is pushed beneath another  

∙ Transform- the plates slide horizontally past each other. Crust is  neither produced nor destroyed  

Divergent Plate Boundaries  

∙ Plates move apart from one another  

∙ Also known as seafloor spreading  

∙ Rifting occurs on land  

 Two places this occurs is Ireland and Africa  

∙ Igneous intrusions, commonly basalt, forming new ocean crust  Convergent Plate Boundaries

∙ Plates move towards one another  

∙ Crust is destroyed by subduction or shortened and uplifted for  continental collision

Continental Collision  

∙ Continental collision form mountain belts with:  

 Folded sedimentary rocks  

 Faulting  

 Metamorphism  


∙ An oceanic plate is pushed beneath another plate, forming a deep-sea trench 

∙ Rocks and sediments of downward- moving plate are subducted into  the mantle and heated  

∙ Partial melting occurs in the mantle. Molten rock rises to form  volcanoes

Ocean-to-Ocean Subduction  

∙ An oceanic plate is subducted beneath another oceanic plate, forming  a deep-sea trench, with an associated basaltic volcanic island arc ∙ An oceanic plate is subducted beneath a continental plate, forming a  trench adjacent to a continent, and continental volcanic arc  mountain along the edge of the continent 

Transform Plate Boundaries  

∙ Plates slide past one another  

∙ No crust is created or destroyed  

∙ Transform faults link/offset mid-ocean ridges and convergent  boundaries  

∙ A natural consequence of horizontal spreading of seafloor on a curve  globe  

∙ Example: San Andreas Fault  

The Big Bang Theory:

∙ Calculations indicate that the big bang occurred 13.7-18 billion years ago

∙ The Big Bang marked the instantaneous creating of all matter in the  Universe followed by an expansion

∙ This matter, almost entirely hydrogen and helium, slowly began to cool and condense into the first starts and galaxies

Nebular Theory  

∙ Rotating cloud called the solar nebula  

∙ Composed of hydrogen and helium, and microscopic dust from  supernova

∙ Solar nebula began to contract about 5 billion years ago  ∙ A diffuse, roughly spherical slowly rotating nebula begins to contract  ∙ As nebula cloud condense, it becomes a flat disk shape  ∙ Gravity attracts particles to one another and clumps of matter begin to form

 With the protosun (pre-Sun) at the center and protoplanets  revolving around it  

∙ Heavier elements pulled towards center of nebula 

 Inner planets begin to form from metallic and rocky substances  Larger outer planets began forming from fragments of ice (H2O,  CO2, and others)

Formation of Early Archean Crust  

∙ During the bombardment, Earth experienced heating and partial  melting of mantle rocks from impacts  

∙ The surface may have been covered by an extensive magma ocean  of molten mantle rock during Early Archean  

∙ This magma cooled to form a basalt oceanic crust

∙ The first oceanic crust formed about 4.5 billion years ago  Origin of Continental Crust  

∙ Granite continental crust formed in subduction zones where  descending slabs of oceanic crust partially melted and magma rose to  the surface where it cooled to form continental crust  

∙ Volcanic island arcs collide to form continental crust 

Origin of Continental Crust  

∙ Continental crust developed after the initial oceanic crust  ∙ Granite continental crust begena forming around 4.4 billion years ago   Evidence from 4.38 bya rocks in Australia (oldest dated rocks on  Earth), 4.04 bya rocks in Canada, 3.9 bya rocks in Antarctica by  zircon dating  

 Bya= Billion years ago  

Early Atmosphere  

∙ Early atmosphere was composed of gases released from volcanic  activity, meteorites, and comets (frozen gases, ice and dust) ∙ The atmosphere was right in nitrogen (N2), with carbon dioxide (CO2)  and probably substantial amounts of hydrogen sulfide (H2S),  hydrochloric acid (HCl), and water vapor (H2O)

∙ CO2 dissolved in the water produced acid rain 

∙ No free oxygen in the atmosphere during the Archean  

∙ Any free oxygen during the Archean was rapidly combined with other  elements (oxidation)  

 Often free oxygen was used up to produce iron oxide  

∙ Whatever oxygen was produced in the environment immediately  combined with iron to form Banded Iron Formations (BIF)  

∙ The appearance of BIFs is evidence of biogenic activity releasing  oxygen into the environment  

∙ Much of the iron (and other metals) may have been released from  hydrothermal vents  

∙ These may also have served as the first habitats for life on the planet

Earth’s Earliest Glaciation  

∙ By 2.8 Billion years ago, Earth had cooled sufficiently for  glaciation to occur. Earth’s earliest glaciation is recorded in 2.8  billion-year-old sedimentary rocks in South Africa  

Shields and Cratons  

∙ Most of what we know about Precambrian is based on studies of  rocks from cratons—portions of continents which have been  deformed since Precambrian or Early Paleozoic 

∙ Areas where Precambrian rocks are exposed are shown in yellow  ∙ The most extensive exposures of Precambrian rocks are in  geologically stable regions of continents called shields  

∙ Canadian shield in North America. Mostly igneous and  metamorphic rocks; few sedimentary rocks  

∙ Stable regions of the craton where shields are covered by  sedimentary rocks are called platforms 

Earliest Evidence of Life

∙ The earliest evidence of life occurs in Archean sedimentary rocks   Stromatolites (trace fossils)

 Microscopic cells of prokaryotes (Body Fossil)

 Algal filaments (Body Fossil)  

 Molecular Fossils (Chemical Evidence)

Stromatolites (Trace Fossil) 

∙ Stromatolites form through the activity of cyanobacteria in the tidal  zone. The sticky mucilage-like algal filaments of the cyanobacteria trap carbonate sediment during high tides  

∙ More abundant in Proterozoic rocks than Archean rocks   Oldest are ~3.5 Billion years old, Australia  

 Likely produced free oxygen that was used to produce BIFs

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