Exam 2 Flashcards
What is a sediment?
A collection of loose earth minerals
What counts as an earth mineral?
Rocks, minerals, soils, and fossils
Where on earth is very little sediment found?
At the tops of mountains
How can sediments form?
Rocks breaking apart, rocks dissolving and re-precipitating elsewhere, animals extracting ions to build shells
What are the two most common ways sediments can form?
Chemically, and clastically
How can sediments form chemically?
Minerals precipitate out of a solution
How can they form clastically?
Broken pieces of earth materials
What is the difference between physical and chemical weathering?
Physical is breaking apart rocks, while chemical alters rocks to create new compounds
Where does weathering happen?
In highlands at the source rock
What are the four agents of erosion?
Water, air, ice and, gravity
What is likely to carry more sediment?
Something which is fastmoving
When can clasts be deposited?
A drop in velocity and viscosity
What type of sediment is more likely to stay where they are?
Coarser and larger sediment
What is the Hjulstrom Diagram?
It predicts the critical velocities of a given grain size and determines where it will be picked up, moved and deposited by flowing water
Why is clay hard to erode?
Clay clumps together
What are the three environments sediments are deposited in?
Continental, coastal, and marine
Where do sediments tend to gather?
In low spots (such as the ocean)
What are some primary sedimentary structures?
Graded bedding, symmetrical ripples, asymmetrical ripples
What are primary sedimentary structures?
Structures which form at the same time as sedimentary rocks
What are secondary sedimentary structures?
Occurs after deposition
What are some examples of secondary sedimentary structures?
Mud cracks, bioturbation, soft sediment deformation
What is the process where sediment turns to stone?
Lithification
What are the two parts of lithification?
Compaction, and cementation
What are the three types of sedimentary rocks?
Siliclastic rock, chemical sedimentary rock, and bioclastic rock
How are metamorphic rocks made?
Begins with a parent rock (Protolith)
How are protoliths metamorphized?
Heating, squeezing, or hot fluids (or a mix of these three)
When is a rock no longer considered to be metamorphic?
When it melts
What is hydrothermal metamorphism?
When hot fluids are the main agent of metamorphism
What is the difference between lithostatic and directed stress?
Lithostatic stress is applied equally to all sides, and directed stress is applied higher in one direction
Does metamorphism affect the composition of the rocks?
No, as elements aren’t added nor removed – they are merely rearranged
What is the difference between re-crystallization and neocrystallization?
Minerals change size and shape without changing compositions vs using the same minerals, growing new crystals that weren’t present in the protolith
How does foliation form?
Dependent on how close a rock is to the collision site, and how much pressure was applied
What are the two ways we can date rocks and fossils?
Relative and absolute dating
What are the seven principles of relative dating?
Principle of..
- Superposition
- Original Horizontality
- Lateral Community
- Cross-cutting relationship
- Inclusions
- Uniformity
- Faunal Sucession
What is the principle of superposition?
Sediment are deposited over time, with oldest being at the bottom, and youngest at the top
What is the principle of original horizontality
Sediments are always deposited in horizontal layers
What is the principle of lateral continuity?
Because beds are always deposited horizontally, you can trace back unformed layers – even if some of the layer had been eroded away
What is the principle of cross-cutting relationship?
A feature which cuts across a rock bed is younger than the rock surrounding it
What is the principle of inclusion?
Rock inclusions are older than the host rock surrounding it
What is the principle of uncomformity?
An unconformity (erosional surface) are younger than the rocks below
What is an unconformity?
Where time is missing from the rock record
What is the principle of fauna succession?
The order in which fossils are first and last seen in the rock record
What is the difference between relative and absolute dating?
Relative determines a rough timeline, while absolute dating determines exact numerical values
How are radioactive isotopes determined?
By measuring half-lives
What are the four divisions of the Geological Time Scale? (From oldest to youngest)
Eons -> Eras -> Periods -> Epochs
When were fossils uncommon?
4 million years ago
What are fossils?
Preserved evidence of ancient life
What is a factor which determines if an organism turns into a fossil?
How quickly it is buried and protected from scavengers, the elements and decay
What are the nine ways to fossilize an organism?
1) Freeze them
2) Jerkification
3) Encasement
4) Replacement
5) Permineralization
6) Petrification
7) Recrystallization
8) Carbonization
9) Molds and casts
What is an example of jerkification?
Mummification
What is an example of encasement?
Insects getting trapped in amber, animals getting trapped in tar
What is replacement?
Remains which have been turned to stone, original bone had been dissolved and replaced by a mineral
What is permineralization?
Filling up pore space in bone with depositing minerals and water
What is petrification?
Permineralization + replacement
What is carbonization?
To bury or to squeeze out all water leaving film behind
What is the difference between a mold and a cast?
Mold: Stamp into a sediment which is then removed
Cast: Fills up mold with other sediments, then mold is removed
Which fossilization method leaves remains unaltered?
Freezing and mumification (Jerkify)
What is the modern definition of evolution?
Differential reproductive genes within a population
Who was Charles Darwin inspired by?
Lyell’s “Principles of Geology”
What did both Darwin and Wallace observe?
Pattern and Hypothesized Process
What is a pattern?
Organisms live where they are the best adapted
What is the Hypothesized Process?
Environmental factors which prevent an organism unsuited from the environment from successfully reproducing
How does variation influence natural selection?
Variation provides material for natural selection to act upon (Only the best fitted individuals survive)
When and where does mutation occur?
Randomly inside the DNA
What is evolution?
A change in gene frequency within populations from generation to generation
What does “fitness” describe?
Ability to survive, find a mate, and to reproduce
What is genetic inertia?
More genetic variation (traits take longer to express themselves + more genetic variability)
Where is genetic inertia more likely to occur?
In larger populations
What kind of dangers are smaller populations at risk for?
Vulnerable to rapid extinction, less variability, prone to evolving quicker
What are analogous structures?
Homologous structures that cannot be traced back to a common ancestor
What is convergent evolution?
Though structures evolved from different ancestors, their functions are the same (Wings)
What is the difference between small-scale and large-scale modification?
Small-scale occurs in one generation to the next, large-scale occurs in different species from one common ancestor
How do we define a species biologically? (Changes can be seen in nature)
Members of a group who can breed, and produce offspring
How do we define a species morphologically? (Using the rock record)
Their morphological similarities (Same bone structure)
How do we track biodiversity in the fossil record?
Origination and extinction rate
What are the five known mass extinction events?
- End Ordovician
- End Devonian
- Permo-Triassic
- End Triassic
- Cretaceous-Paleogene
What is a collection of landforms called?
A terrain
What is the difference between relief and slopes?
The relief is the distance between the highest and lowest points (low, moderate, high) and the slope is the change in elevation (shallow, moderate, steep)
What does cooling cause?
Decrease in elevation
How can subsistence (downward movement) be caused?
By stretching the crust (divergence/rifting)
What is a load?
When downward pressure is applied to the crust
What happens when a relief develops?
Can be subjected to weathering and erosion
What factors control the creation of landforms?
Tectonic life forms, volcanic landforms, erosional lifeforms, and depositional landforms
What factors can modify landforms?
Weathering, erosion and deposition
Why is earth not completely flat from weathering and erosion?
Uplift and subsidence continuously move rocks up and down
What are the six factors which determine how a landform is made?
Eroding agent, relief, climate, substrate composition, life activity, and time
What is water most used for in Alberta?
Energy generation and agriculture
What is stream discharge?
The volume of water passing through a point in a specific amount of time
Between turbulent and laminar, which one is better for transporting sediment?
Turbulent flow as chaotic motions promote sheering of larger rocks and mixing of sediments
What is a thalweg?
A part of the stream with the highest flow velocity
What is the difference between a suspending and bed load?
Suspending loads are sediments which are carried in the water, bd loads are particles which directly interact with the bed
What is a dissolved load?
Any sediment which is dissolved in water
What is the purpose of the Hjulstrom Diagram?
tells the relationship between sediment size and the water’s ability to erode and transport sediments
What are the three types of stream channels?
Straight, meandering and braided
How are Oxbow lakes formed?
By meandering cut-offs
What are biogenic sediments?
Sediments formed through biological activity
What are siliclastic sediments made up of?
Feldspar, quartz, rock fragments, clay
What is a source area?
An exposed chunk of rock where sediments form
What is in situ?
A chemical reaction between air or water with a rock
What are two marine depositional environments?
Continental shelf and abyssal plain
What is the difference between beds and lamination?
Beds: >1 cm, lamentation: < 1 cm
Where do symmetrical and asymmetrical ripples form?
Beaches, rivers and deserts
If water is included in metamorphic systems, what happens?
The metamorphic process is sped up
Hydrothermal fluids often contain dissolved elements rejected from normal silicate minerals that form as magma solidifies. What is an example?
Gold
What causes foliation in metamorphic rocks?
Directed stress
What does radiometric dating measure in igneous rocks?
The age of crystallization
What does radiometric dating measure in sedimentary rocks?
The age of the formation minerals in the rock
What does radiometric dating measure in metamorphic rocks?
The age of metamorphism
