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Rock layers go from older to younger (from
bottom to top). This is a
restatement of which relative age principle?
Principle of Superposition
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What is the principle of Original Horizontality?
Layers of sediment are originally deposited horizontally. Any folding happened after desposition
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What is the Principle of Original Continuity?
Sediments generally accumulate in horizontal sheets
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What is the Principle of Cross-cutting relations?
If one geological feature cuts another, the one that has been cut is older
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What is the Principle of Inclusions?
Fragments of rocks included in a layer must be older than that layer.
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What are inclusions?
Fragments of an older rock layer
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What is the principle of Baked Contacts?
A rock that has been contact metamorphosed is older than the intrusion.
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What are the 3 types of Unconformities? What is the difference between each?
Angular -one older layers of sedimentary rocks is tilted/folded/eroded and another is deposited on top
Nonconformity - one layer of metamorphic rocks rests under a deposited layer of sedimentary rocks
Disconformity- one layer of sedimentary rocks is deposited on another layer from a different age
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What is Dendrochronology?
Dating past events through the record of trees and their rings. By correlating rings among trees whose growth periods partially overlapped, we can create a tree ring chronology back through time
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What is the oldest living (non-clonal) tree?
- Bristle Pine
- Was Prometheus at 4862
- Now Methuselah 4840
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What is an Isotope?
Atoms of the same element with the same number of protons but different number of neutrons.
- Carbon has 3 Isotopes
- C12, C13, C14
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What is the age of the oldest whole rock on
our planet?
- Metamorphic rock 4.03 billion
- Igneous rock 3.5 billion
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What is the age of the oldest substance on our
planet?
Sedimentary Detrital Grains 4.4 billion years
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How far back can dendrochronology take us?
12469 Years BP
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What does crude oil
consist of?
unrefined petroleum
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How many protons
does Carbon-14 have?
6 protons, 8 neutrons
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The half-life of Carbon-14 is?
5730 years
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What kinds of substances can be dated using radiocarbon dating?
Anything that was once organic matter
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How is radiocarbon dating calibrated?
Can be compared with things that can be dated by other factors such as dendrochronology and seafloor sediment.
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What is fractionation?
in radiocarbon dating it is the division of the type of carbon isotopes absorbed
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What does BP stand for?
Before Present (1950)
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The decay product of radiometric decay is called…
beta particles
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The oldest rocks in our solar system are this old
4.6 billion years old
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What are the oldest rocks in our solar system called?
meteorites(?)
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How many times have humans walked on the moon?
6
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Cutting a cake with a knife demonstrates this principle of relative age dating?
principle of cross cutting
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A stream that cuts perpendicularly through a hill forms this
River gap
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The cutoff loop of a meandering stream is known as this
oxbow
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When a riversteals another river’s water we call this
Stream piracy
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What are the 4 watersheds in North America?
- Great Basin
- Arctic
- Atlantic
- Pacific
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Which watershed runs into the Gulf of Mexico?
Pacific
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Is this watershed is closed?
No
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Glacial Accumulation vs Ablation
- Accumulation is where snow fall adds to the glacier
- Ablation is where the glacier loses mass
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What is Glacial till?
Poorly sorted sediment with angular clasts transported within glacial ice
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What is Loess?
Clay to silt-sized glacial sediment transported from outwash plain and glacial surface by winds
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What is a Glacial Period?
interval of time during which the climate is cold enough to allow for a significant advance of continental and mountain glaciers
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A circular scoured-out (flowing water) glacial feature is called?
Glacial Pothole
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Glacial debris that separates two separate, parallel ice tongues forms this
medial moraine
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What are the different ways a stream carves a channel?
- Scouring-removal of loose sediments
- Abrasion-particles grind against channel floor and walls
- Breaking-push of water can break off part of the channel floor or the river bank
- Dissolution- water dissolves soluble minerals in the surrounding rocks
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How does a stream carry sediment?
- Bed load- material in contact with the substrate (bottom of the stream/river)
- Suspended load-material floats in water
- Dissolved load- material chemically dissolved in water
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Windblown glacial sediment is known as?
loess
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A stream that was “lowered” onto a mountain chain is called?
superposed stream
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Characteristics of a Meandering Fluvial System
- low gradient
- mostly sand, silt, mud
- well developed flood plain
- sinuous channel
- continuous water flow
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What are scroll bars?
Scroll bars are the result of the lateral migration of a meandering stream. the river will push outward around a curve due to the differing velocities of the water
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Characteristics of a Braided Fluvial System
- large sediment load
- easily erodible banks
- abundant coarse sediment
- rapid discharge fluctuations
- very wide
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Name of a superposed stream
Goosenecks, San Juan
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How deep is the boundary between ductile and brittle deformation in a glacier?
60meters
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A substance starts out with 60 parent isotopes. How many after 2 half lives?
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The deepest a river can carve into bedrock is controlled by local what?
- rock hardness
- relation to sea level => local base level
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What channel types are there?
- Resistant rocks -deep with steep slopes
- Soft rocks- can be deep with angled slopes
- Both- stair step canyons when channels cut through sediments of hard/soft rocks
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Waterfalls are an example of this fluvial erosional feature?
breaking (knickpoint migration)
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The tallest waterfall in the world is found in this country
- Angel Falls, Venezuela
- Most volume Inga Falls, Congo
- Widest Chutes de Khone, Laos
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A stream that carries water only once per year is called this
Ephemeral Stream
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The boundary between two watersheds is called
Continental divide
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What sedimentary features forms on the inside of a meander?
scroll bar
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This type of river carries large amounts of coarse grained sediment
braided river
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Marble Canyon in the Grand Canyon has great examples of these
unconformities
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What are the different waterfall causes?
- Resistant Rock Layers
- Fault Scarps
- Tributaries lead to a ledge into a trunk stream
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Gradual Vs Rapid Erosion
- Gradual = normal conditions
- Rapid = flood stage =>centuries worth of gradual
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The Scablands of Washington State were carved, rapidly or slowly?
Rapidly by giant meltwater floods at the end of the Ice Age
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A single large, out-of-place glacial boulder is called?
Glacial Erratic
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Why do Niagara Falls exist?
Large Fault Escarpment
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An erosional surface between a sedimentary and metamorphic rock is called?
nonconformity
-
An erosional surface between two sedimentary rocks is called?
disconformity
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How is the amount of C14 remaining calculated?
Counting the number of C14 atoms present or capture of beta particles
- Gas proportional counter
- radiation counter
- large samples (grams)
- slow process (days to weeks)
- low resolution with small samples
- liquid scintillation counter
- radiation counter
- large samples (grams)
- slow process (days to weeks)
- low resolution with small samples
- mass accelerator spectrometer
- isotope counter
- small samples (micrograms)
- fast process (hours to days)
- very high resolution
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The oldest substance on our planet is called?
Zircon Crystals (ZiSiO4)
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Name at least two places in the world that bear continental glaciers
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By how much have global average temperatures risen over the last ~100 years?
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What is stratigraphy?
the study of the nature, age, and geometric relationship of rock layers
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What is radiometric dating?
- the age record of rocks
- Rocks themselves are not dated, but rather the materials that make them up
Can't date sedimentary rocks since they are made of sediments from different times
Dating metamorphic rocks would find the last metamorphism since each one resets the time counter
Can date igneous rocks, mineral crystals formed during solidification of the the melt
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How is decay rate (half-life) measured?
Laboratories with tiny samples that are enormous on the atomic scale allow observation of decay
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What are the different types of Drainage patterns?
- Dendritic-forms when slope and substrate is uniform
- Radial- forms on slopes of cone shaped mountains (volcanoes)
- Rectangular- streams follow regularly fractured rocks
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What is headward erosion?
the extension of the beginning of a tributary due to erosion
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What are Milankovitch Cycles?
Changes in Earth Orbit Eccentricity- change in the degrees of earth's axis
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How does coal form?
- Coal swamps
- near shore
- fresh or salt water
- flat
- stagnant waters
- near sea level
- => organic matter forms peat
- change in sea level buries it w/ sediment=> pressure and temperature change it to coal
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How does oil form?
micro organisms die and sink to the bottom of the ocean => sediment buries the organic matter =>compression and temperature change it to oil
Anticlines- oil migrates upward so must be trapped inside of porous rock under impermeable rock. If not seeps to the surface as an oil seep
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Products of Crude oil refinement
- bottom coke is used for plastics
- motor oil
- kerosene
- gasoline
- vapors
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Common uses of oil
- liquid: refrigerants
- plastics
- fabrics: nylon & polyester
- agriculture
- medical
-
Challenges for renewable alternatives
- replace 150 year global fuel economy
- fuel transportation
- fuel electricity
- replace fossil fuel produced products
- make profits
- replace jobs
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Mountain vs Continental Glacier
- Mountain-in or next to mountains at high altitudes and/or high latitudes
- Continental- over vast stretches of land at high latitudes
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Requirements for a Glacier
- cool summers
- enough snowfall
- gentle slope
- little wind
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Formation of Glacial Ice
layers of snowfall build up pressure for lower layers to form compressed ice with little air
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What are Crevasses?
Cracks that form in the upper brittle layer of glacier when ice beneath flows, NO deeper than 60 meters
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Why do Glaciers move?
- Ice flows because the pressure makes the lower ice ductile and viscous
- Ice slides because in the summer the ice melts and lubricates the bottom
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What is an Arête?
thin ridge or spoke of rock carved between two parallel glacial valleys
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What is a Cirque?
a bowl-shaped depression on side of mountain where glacial ice originated and flowed from
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What is a Drumlin?
Deposit of sediment that was shaped into a tear-shaped hill by overrunning glacial ice
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What is a Hanging Valley?
A shallow valley formed by a small glacial tributary as it joined with the large main glacier
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What is an Esker?
former subglacial meltwater stream that was clogged with sediment as glacier melted
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What is a Horn?
a tall, steep-faced mountain that formed as the result of converging cirques
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What is a Kettle Lake?
water-filled depression formed when large junks of ice were left behind by receding glacier
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What is an Outwash Plain?
surface in front of glacial tongue that is covered by water-reworked glacial sediment
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What is a Tarn?
A lake inside of a cirque
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What is a Terminal Moraine?
a ridge-like structure formed from debris that melts out of the ice at the toe of the glacier
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What is a U-shaped Valley?
a glacially carved valley that is u-shaped in cross-section
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What are Mega-Ripples?
meter-scale ripples, that consist of gravels moved during massive glacial meltwater floods
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What is a Lateral Moraine?
rock debris that melts out of the glacier along the edges of its u-shaped valley
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What is a Fjord?
Water-filled glacial valley due to rising sea level
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What is a Medial Moraine?
rock debris that separates two parallel glacial ice tongues
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