A: Basic, Earth, Time

Question 1

Describe the scientific method and its steps

Answer 1

Observation->Question->Hypothesis->Experiment->Analysis->Conclusion
1. Compile observations
2. Form a hypothesis
3. Test the hypothesis
4. repeated testing raises the hypothesis to a Theory (not a guess, but sth that has been tested many different ways and withstood those tests)
5. If a theory or group of theories are always observed to happen it can become a Law.
6. Continual re-examination

Question 2

What is ESS? And why is it important.

Answer 2

Earth System Science. ESS looks at Earth as a complex system with many interacting parts.

ESS divides the Earth into a series of systems or “spheres” including the atmosphere, the biosphere (all life), the lithosphere (all things to do with the Earth’s crust), the hydrosphere (all bodies of liquid water) and the cryosphere (ice)

The Earth is composed of a series of linked systems arranged in hierarchies that evolved together over geological time. As such ESS is particularly important to the Paleontologists and Geologists when we are trying to decode the deep history of our planet and the life that inhabits it.

Question 3

What is defined a system by ESS?

Answer 3

a system is anything that can be set apart from any other part of existence and studied

Question 4

List the layers of Earth from exterior to interior

Answer 4

Lithosphere, asthenosphere, mantle, outer core, inner core (there are 5 layers)

Question 5

Describe the lithosphere

Answer 5

continental and oceanic crust, the uppermost part of the mantle

this layer is fractured into many rigid sections or plates.

Question 6

Continental crust vs. oceanic crust

Answer 6

they have different compositions
continental crust is richer in minerals containing silica; Continental crust is less dense, thus usually subaerial (high standing and well above sea level)
oceanic crust has higher iron content. Oceanic crust is much thinner but much denser. Usually submarine (covered by oceans)

Question 7

What can rocks be thought of as

Answer 7

Aggregates of minerals

Question 8

Define mineral

Answer 8

A naturally occurring crystallion inorganic substance with an ordered arrangement of atoms

Question 9

What are the 3 main categories of rock?

Answer 9

Igneous, metamorphic, sedimentary

Question 10

Describe igneous rocks

Answer 10

They crystallize (process known as solidification) from molten material (called a melt) to form rock of interlocking crystals

can be plutonic/ intrusive, or extrusive

Question 11

Plutonic/ intrusive vs extrusive rocks? What are they

Answer 11

They are both igneous rocks

Plutonic:
Initially buried under other rocks and soil, plutonic rocks are eventually exposed at the surface via weathering and erosion. Because plutonic rocks cool slowly in the subsurface they generally possess large crystals.

Extrusive:
extrusive rocks cool rapidly and as a result, have very small, often microscopic, crystals.

Question 12

Describe metamorphic rocks

Answer 12

They are rocks formed by altering of pre-existing rocks (of any category) via metmorphism

The processes that transform or metamorphose rocks involve heat and/or pressure and very often fluids percolating through the subsurface. Rocks can be compressed and flattened and new minerals may be generated that are more stable under the new temperature and/or pressure conditions. Pressure is often the result of compressional tectonic forces generated when plates collide; this can also generate heat. In addition, pressure and temperature will increase with depth.

Question 13

Describe sedimentary rocks

Answer 13

Sedimentary rocks form by a number of processes. These processes can generally be classified as:

Physical erosion and weathering of another rock to form a clastic sedimentary rock such as a sandstone, siltstone, or mudstone. These rocks are composed of the fragments and grains of the rock(s) that were being eroded to form the sediment.

Chemical precipitation to form an evaporite. These form when a body of water such as a lake or inland sea evaporates to form layers of salt. It is this process that produces most commercially mined salt.

Biological precipitation of minerals includes the production of coral reefs, sediments composed of shells, clams, or the skeletons of microscopic plankton (often producing limestone), and deposition of plant material in swamps to form peat and eventually coal.

Question 14

True or False: Every rock passes through each stage in the rock cycle

Answer 14

False

Question 15

How old is Earth

Answer 15

4.5 billion years

Question 16

What period did we find the oldest fossils?

Answer 16

Archean

Question 17

Explain the earliest ways of estimating Earth’s age

Answer 17

James Ussher estimated age of Earth using the Bible, at just over 6000 years old.
Geroge Louis De Buffon hypothesized Earth solidied from a molten state: so he constructed iron spheres, heated till they were hot, and times how long it took for them to cool to room temp. Then used a time scaling factor relative to the scale of the Earth model he used (iron spheres), he estimated Earth was around 75000 years old.

Question 18

Define stratigraphy

Answer 18

the study of rock strata (layers of sedimentary rock or layered igneous rocks), particularly the sequences of layers, and the information this provides on the geological history and relative ages of a region
alternative def’n: the way in which rocks (mostly sedimentary) are laid down

Question 19

How can stratigraphy help us, and what are its downfalls?

Answer 19

By viewing rock strata in terms of straigraphic sequence, each layer having a chronology or point in geological time, then we can estimate the passage of time; e.g. we will know how long it took for some rock formations to build up.

Downfalls:
1. constant rate of deposition of sediment can’t be assumed always
2. sediment may have been actively eroded from the sedimentary pile before it was lithified into rock and/or
3. deposition of large volumes of sediment causes compaction of the sedimentary pile, resulting in underestimate of total amount of accumulated sediment

Question 20

What’s relative dating?

Answer 20

determining the relative order of past events, without necessarily determining their absolute age in years; developed from laws of stratigraphy

Question 21

List the main stratigraphic principles by Nicolas Steno

Answer 21

Principle of Superposition, Principle of Original Horizontality, Principle of Lateral Continuity and Cross-Cutting Relationships)

Question 22

Explain the Principle of Original Horizontality

Answer 22

This principle states that rocks that are currently folded or tilted were once deposited as flat horizontal layers.

Question 23

Explain the Principle of Superposition

Answer 23

This states that in a stack of sedimentary rocks, the layers (beds) at the bottom of the pile will be the oldest. (what’s on top is youngest)

Question 24

Explain the Principle of Lateral Continuity

Answer 24

Strata extend horizontally in all directions. The strata will continue until:

1. It thins – sedimentary layers will become thinner the further it is transported away from the source of that sediment.
2. It grades into another sediment type - imagine sandy sediments that were deposited on a beach passing gradually laterally into finer sediments that were deposited in the deeper parts of an ocean.
3. It comes to the edge of the depression into which the sediment was being deposited – imagine sediment deposited in a lake … it will thin and cease to be present once it reaches the margin of the lake.

Question 25

What kinds of rock strata exist?

Answer 25

Flat horizontal strata, tilted strata, folded strata (syncline is ‘dip’ part, anticline is ‘pointy’ part), unconformities (e.g. angular unconformity)

Question 26

Explain James Hutton’s info on cross cutting relationships and unconformities

Answer 26

he noticed ‘breaks’ or gaps in geological record of strata

Question 27

what may be the cause of unconformities?

Answer 27

major geological events, like mountain-building

Question 28

What sequence of events could lead to the formation of an angular unconformity?

Answer 28

1. Deposition of horizontal sediments in ocean and subsequent burial underneath younger sediments.
2. Lithification and folding of sediments;
   uplift and erosion of folded sedimentary rocks.
3. Return of ocean and deposition of sediments atop of erosion surface.
4. Continued deposition of new sediments.

Question 29

Explain the various cross-cutting relationships

Answer 29

Faulted strata: occur when there is a fracture in the rocks along which some movement (movement along faults generates earthquakes)

Intruded strata: when hot molten rock has forced its way thru an older series of rock layers and then cooled it, forming an intrustive igneous rock

Question 30

What is biostratigraphy?

Answer 30

Biostratigraphy is based on the principles of stratigraphy as it relates to the passage of geological time. Leonardo da Vinci was probably one of the first people to understand that fossils were the remains of once living organisms but it was an English engineer, William Smith (1769-1839) who recognized its importance in stratigraphy.

Question 31

Explain William Smith’s Principle of Faunal Succession.

Answer 31

Smith’s Principle of Faunal Succession states that different types of fossils can be found in a regular order through sedimentary rock layers.

Question 32

Explain what is the fossil range

Answer 32

the time that a fossil exists (the time between its evolution and eventual extinction)

Question 33

What technique does absolute dating use?

Answer 33

Absolute dating uses an understanding of radioactive decay to date rocks. The technique is also called radiometric or radioactive dating.

Question 34

Explain the technique for absolute dating; i.e. explain radiometric or radiactive dating.

Answer 34

During radioactive decay the nucleus of a radioactive atom (the parent atom) spontaneously reacts. This results in the production of an atom of a different element (the daughter atom) and the release of radiation energy.

Question 35

Absolute dating must be used in conjunction with relative dating in studies of Earth history, why?

Answer 35

A radiometric date will only be valid if it can be demonstrated that the decay took place in a closed system, namely where there has been no contamination or loss of either parent or daughter material. The best closed systems are crystals in igneous rocks.

Other limits:
Weathering can cause leakage of isotopic material;
Metamorphism resets the isotopic clock such that any date obtained from the rock would date from the time of metamorphism and not the original formation of the rock;
Radiometric techniques cannot be used on sedimentary rocks, the most common rocks at the Earth’s surface.

Question 36

What are the 3 parts of the Mesozoic era?

Answer 36

Mesozoic Era, the time between 251 and 65 million years ago (Ma).
This Era is composed of three Periods, listed below from youngest to oldest:

Cretaceous: 144 - 65 Ma
Jurassic: 201 - 144 Ma
Triassic: 251 - 201 Ma

Question 37

What are fossils? Describe the 2 broad categories of fossils

Answer 37

Fossils = preserved remains or traces of animals, plants, other organisms from the remote past.

1. Physical fossils = bones, shells, also rarer fossils like gastroliths (stomach stones from large plant eating dinos; they were swallowed to help grind plant material). Skin impressions. Corpolites (fossil poop). Eggs.
2. Trace fossils / ichnofossils = tracks and trails left by organisms and preserved in the geological record

Question 38

What is the fossil record?

Answer 38

The totality of fossils, both discovered and undiscovered, and their placement in fossiliferous (fossil-containing) rock formations and sedimentary layers (strata)

Question 39

How are fossils formed?

Answer 39

Many ways. Amber, freezing, mineralization, impressions.
Common way is mineralization, the replacement of organic material by inorganic minerals.
Also common mode of fossilization: moulds and casts (original remains not present or completely dissolved; hole in rock = mould, if filled with sediment or mineral = cast)
Most common dino fossils are mineralized remains of bones and teeth.
Finest form of mineralization is called permineralization (atom by atom replacement of original organisms tissues and/or bones by minerals)

Question 40

Permineralization?

Answer 40

The finest form of mineralization. Atom by atom replacement of original organisms tissues and/or bones by minerals

Question 41

What are bones composed of?

Answer 41

Calcium phosphate and organic material

Question 42

What are some common mineralizing media?

Answer 42

calcite, iron minerals, and silica

Question 43

How does mineralization work in fossils?

Answer 43

When fluids containing certain precipitate materials percolate through fossil and leave and form the fossil

Question 44

How are impressions type fossils formed?

Answer 44

Impressions are just what something used to look like, they’re usually soft. E.g. a leaf fall to lake bed and leaves behind an imprint of what a leaf used to look like.

Question 45

What are moulds and casts?

Answer 45

Common mode of fossilization. Original remains not present or completely dissolved.

hole in rock = external mould,
if filled with sediment or mineral = cast
if internal space filled but original shell/bone gone = internal mould

Mould: a negative imprint of the surface of the fossil
Cast: preserved the external surface of the organism (may have original material preserved)

Question 46

Describe the common processes of fossilization

Answer 46

1. Physical changes- organisms may become flateened
2. Chemical changes-
   Diagenesis = preocesses that convert sediment to a rock
   Also change carcass in sediment- will react different depending on what original composition of material was

Question 47

How does environment affect fossilization potential?

Answer 47

Terrestrial- poor fossilization potential (reasons: rapid rotting; so land animals/plants/ flying organisms may not preserve well)
Aquatic- better fossilization potential (esp. if living in bottom of lake/ocean due to less currents); swimming organisms usually poor potential due to predation and currents.
Burrowing organisms probably highest preservation potential due to already buried in sediments

Question 48

List the factors that can affect the preservability / fossilization potential of a creature.

Answer 48

composition of the creature

the environment where the organism lived and died

processes affecting the dead organism

Question 49

What is taphonomy? What are some taphonomic processes?

Answer 49

The study of processes that affect a creature prior to it becoming a fossil.

These taphonomic processes include decay (necrolysis) and movement of the corpse.

Question 50

Describe necrolysis. And what factors determine the degree of necrolysis?

Answer 50

Necrolysis is decay of the corpse. Necrolysis starts a few minutes after death and will continue until the destruction of the corpse or until fossilization.

Factors that determine degree of necrolysis:
1. supply of oxygen- less available oxygen, fewer scavengers/microbes exist; e.g. swamps, bottom of some large bodies of water like Black Sea

2. pH extremes- acidic areas effectively transform flesh into a kind of leather (e.g. peat bogs)
3. temperature- the lower the temp, the less microbial activity occurs and the more decay is prevented
4. nature of the organic carbon- organical material like fats and muscles decay relatively rapidly; other types decare slower (e.g. cellulose in plants)
5. movement of the corpse (biostratinomy)- corpses may be moved by scavengers of physical processes (wind and water transport)

Question 51

What is paleoenvironment?

Answer 51

The environment which a creature (dead) once inhabited

Question 52

List the steps of how marine animals with a hard shell become fossils.

Answer 52

1. Original shell buried by sediment. Inside of shell filled with sediment. Sediment becomes rock.
2. Shell dissolves
3. Shell replaced with sediment of mineral precipitate

In the preserved fossil, there will be an ‘external mould’, a ‘cast’ of the original shell, and the impression of the inside of the shell called the “internal mould”.

Question 53

List the different types of morphologies

Answer 53

functional morphology: How did the organisms move?

developmental morphology: How did the organisms grow?

behavioural paleontology: What did the organisms do?

interaction between organisms: How did the organisms interact with other organisms in their environment?

Question 54

What are trace fossils

Answer 54

Trace the fossil tracks. Can examine the way creatures moved and interacted with environment

Question 55

What are bone beds

Answer 55

Concentrations of dino bonews

Question 56

Where to find dinos in…
Fluival (river) environments?
Lacustrine (lake) environments?
Aeolian (desert) environments?
Deltaic (delta- formed when river enters a body of water) environments?

Answer 56

Fluvial- most common sedimentary environment to find fossil in. Open sources of water attract large animals and a flowing river can rapidly cover a dinosaur corpse with sediment. But fossils usually found in pieces, unless on flood plains next to rivers due to slower water flow and more finger-grained sediment to cover corpse.

Lacustrine- dinos found in fine sediments around lake margins or one river deltas; no fossils in deeper lake sediments suggest few dinos were aquatic

Aeolian- very rarely found in deserts due to wind-blown silt and sand very abrasive and erosive.

Deltaic- yes

Question 57

Explain Alfred Wegener’s Theory of Continental Drift

Answer 57

He was the first person to postulate that the existing contients were originally joined as one large land mass (i.e. Theory of Continental Drift)

Question 58

Why are plate tectonic processes so important?

Answer 58

They move 100 km / million years.

1. Almost all earthquakes, and most volcanoes, occur where lithospheric plates are interacting with one another;
2. Most of our main mineral and hydrocarbon resources occur in very specific tectonic settings; and
3. Plate tectonic processes going on at depth are almost entirely responsible for what happens at the Earth’s surface, including the size and shape of oceans, the nature and distribution of landforms, and the general climatic conditions that each part of the Earth’s surface experiences.

Question 59

Define paleogeography

Answer 59

The study of the evolution of landforms through time

Question 60

What is sea floor spreading?

Answer 60

New material getting pushed out from deeper hot areas, spreading out material
Essentially:
Magma oozes up at mid ocean ridges, creating a new ocean lithosphere, displaces older crust to either side (spreads away from crest)
Ocean lithosphere removed as it sinks into mantle at ocean trenches (subduction)

Sed floor spreading causes continents to get carried as ocean floor spreads away from ridges

Question 61

Why is there so little sediment on ocean floor and why are fossils no more than 180 million years old?

Answer 61

Because the oceans are relatively young compared to the continents, as it’s an ongoing process

Question 62

How does the age of ocean plate change from the ridge crest to the ocean trenches?

Answer 62

Youngest at ridge, getting progressively older away from the ridge

Question 63

How are Earth’s layers described by?

Answer 63

Their chemical composition and their relative rigidity- how they behave when stressed

Question 64

Define a plate. What is a tectonic plate composed of?

Answer 64

Plates are fractured blocks of lithosphere “floating”on ductile / plastic
asthenosphere mantle.

A plate is composed of Lithosphere (a unit defined by its physical properties) =
Crust + Upper Mantle

Question 65

Where does the most dynamic geological activity take place in the plates?

Answer 65

At plate boundaries

Question 66

Describe Divergent/ Constructive Margins

Answer 66

Plates move apart - molten material rises and fills the gap = new ocean curst
Characterized by shallow earthquakes, basaltic volcanic activity

Question 67

Where are divergent/ constructive margins usually located?

Answer 67

Under the ocean (exception of Iceland)

Question 68

Describe Convergent/ Destructive margins

Answer 68

Plates collide: 3 fold sub-classification
A. Ocean- Continent Convergence: ocean lithosphere subducts below continents due to density difference
Folding/uplift of mountains/ crustal shortening/thickening
Shallow-deep earthquakes
Development of ocean trench and accretionary wedge
Magma generated at these boundaries by subduction is usually more rich in silica and sticky; explosive eruptions

B. Ocean-Ocean Convergence: which plate subducts? Depends on age and temperature! The older/ colder plate subducts below the younger; fromation of volcanic isalnd arcs
Shallow- deep focus earthquakes
Also development of ocean trench and accretionary wedge
Magma is not as explosive but can get lots of dust

C. Continent - Continent Convergence: plates not dense enough to be subducted into mantle –> form large mountains (e.g. Tibetan range)
Folding/ crustal shortening/thickening
Earthquakes are shallow to medium depth.
No volcanic activity

Question 69

Describe Transform Boundaries

Answer 69

Plates move past each other with no
net formation or destruction of
material. Transform zonesommonly found with ocean plates too.
Not associated with volcanic activity

Shalllow focus earthquakes.
Example: San Andreas Fault, Pacific/ North American Plates

Question 70

Describe Conservative/ Passive Boundaries

Answer 70

*Area between different types of lithosphere on same plate
* Represents where continents rifted apart
* Earthquakes, rare, no volcanic activity

Question 71

Note: some features cannot be linked to plate boundaries, but can still be explained by plate tectonics. Give an example.

Answer 71

Movement of plates above a mantle plume can form volcanic structures and island chains.

Question 72

List the different ways lithospheric plates interact with one another.

Answer 72

1. Divergent boundaries (plates moving apart from one another)
2. Convergent boundaries (plates moving towards one another)
3. Transform boundaries (plates sliding along one another)

Question 73

How are oceans formed?

Answer 73

Via divergent margins.
Evolution of an Ocean Basin.
A) Continent undergoes extension;
B) The crust is thinned and a rift valley forms;
C) Continent tears into two; continent edges are faulted and uplifted; basalt magma erupts from oceanic crust;
D) The ocean widens and a mid-oceanic ridge develops.