Rock layers go from older to younger (from
bottom to top). This is a
restatement of which relative age principle?
Principle of Superposition
What is the principle of Original Horizontality?
Layers of sediment are originally deposited horizontally. Any folding happened after desposition
What is the Principle of Original Continuity?
Sediments generally accumulate in horizontal sheets
What is the Principle of Cross-cutting relations?
If one geological feature cuts another, the one that has been cut is older
What is the Principle of Inclusions?
Fragments of rocks included in a layer must be older than that layer.
What are inclusions?
Fragments of an older rock layer
What is the principle of Baked Contacts?
A rock that has been contact metamorphosed is older than the intrusion.
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
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
What is the oldest living (non-clonal) tree?
- Bristle Pine
- Was Prometheus at 4862
- Now Methuselah 4840
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
What is the age of the oldest whole rock on
- Metamorphic rock 4.03 billion
- Igneous rock 3.5 billion
What is the age of the oldest substance on our
Sedimentary Detrital Grains 4.4 billion years
How far back can dendrochronology take us?
12469 Years BP
What does crude oil
How many protons
does Carbon-14 have?
6 protons, 8 neutrons
The half-life of Carbon-14 is?
What kinds of substances can be dated using radiocarbon dating?
Anything that was once organic matter
How is radiocarbon dating calibrated?
Can be compared with things that can be dated by other factors such as dendrochronology and seafloor sediment.
What is fractionation?
in radiocarbon dating it is the division of the type of carbon isotopes absorbed
What does BP stand for?
Before Present (1950)
The decay product of radiometric decay is called…
The oldest rocks in our solar system are this old
4.6 billion years old
What are the oldest rocks in our solar system called?
How many times have humans walked on the moon?
Cutting a cake with a knife demonstrates this principle of relative age dating?
principle of cross cutting
A stream that cuts perpendicularly through a hill forms this
The cutoff loop of a meandering stream is known as this
When a riversteals another river’s water we call this
What are the 4 watersheds in North America?
- Great Basin
Which watershed runs into the Gulf of Mexico?
Is this watershed is closed?
Glacial Accumulation vs Ablation
- Accumulation is where snow fall adds to the glacier
- Ablation is where the glacier loses mass
What is Glacial till?
Poorly sorted sediment with angular clasts transported within glacial ice
What is Loess?
Clay to silt-sized glacial sediment transported from outwash plain and glacial surface by winds
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
A circular scoured-out (flowing water) glacial feature is called?
Glacial debris that separates two separate, parallel ice tongues forms this
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
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
Windblown glacial sediment is known as?
A stream that was “lowered” onto a mountain chain is called?
Characteristics of a Meandering Fluvial System
- low gradient
- mostly sand, silt, mud
- well developed flood plain
- sinuous channel
- continuous water flow
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
Characteristics of a Braided Fluvial System
- large sediment load
- easily erodible banks
- abundant coarse sediment
- rapid discharge fluctuations
- very wide
Name of a superposed stream
Goosenecks, San Juan
How deep is the boundary between ductile and brittle deformation in a glacier?
A substance starts out with 60 parent isotopes. How many after 2 half lives?
The deepest a river can carve into bedrock is controlled by local what?
- rock hardness
- relation to sea level => local base level
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
Waterfalls are an example of this fluvial erosional feature?
breaking (knickpoint migration)
The tallest waterfall in the world is found in this country
- Angel Falls, Venezuela
- Most volume Inga Falls, Congo
- Widest Chutes de Khone, Laos
A stream that carries water only once per year is called this
The boundary between two watersheds is called
What sedimentary features forms on the inside of a meander?
This type of river carries large amounts of coarse grained sediment
Marble Canyon in the Grand Canyon has great examples of these
What are the different waterfall causes?
- Resistant Rock Layers
- Fault Scarps
- Tributaries lead to a ledge into a trunk stream
Gradual Vs Rapid Erosion
- Gradual = normal conditions
- Rapid = flood stage =>centuries worth of gradual
The Scablands of Washington State were carved, rapidly or slowly?
Rapidly by giant meltwater floods at the end of the Ice Age
A single large, out-of-place glacial boulder is called?
Why do Niagara Falls exist?
Large Fault Escarpment
An erosional surface between a sedimentary and metamorphic rock is called?
An erosional surface between two sedimentary rocks is called?
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
The oldest substance on our planet is called?
Zircon Crystals (ZiSiO4)
Name at least two places in the world that bear continental glaciers
By how much have global average temperatures risen over the last ~100 years?
What is stratigraphy?
the study of the nature, age, and geometric relationship of rock layers
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
How is decay rate (half-life) measured?
Laboratories with tiny samples that are enormous on the atomic scale allow observation of decay
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
What is headward erosion?
the extension of the beginning of a tributary due to erosion
What are Milankovitch Cycles?
Changes in Earth Orbit Eccentricity- change in the degrees of earth's axis
How does coal form?
- Coal swamps
- near shore
- fresh or salt water
- stagnant waters
- near sea level
- => organic matter forms peat
- change in sea level buries it w/ sediment=> pressure and temperature change it to coal
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
Products of Crude oil refinement
- bottom coke is used for plastics
- motor oil
Common uses of oil
- liquid: refrigerants
- fabrics: nylon & polyester
Challenges for renewable alternatives
- replace 150 year global fuel economy
- fuel transportation
- fuel electricity
- replace fossil fuel produced products
- make profits
- replace jobs
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
Requirements for a Glacier
- cool summers
- enough snowfall
- gentle slope
- little wind
Formation of Glacial Ice
layers of snowfall build up pressure for lower layers to form compressed ice with little air
What are Crevasses?
Cracks that form in the upper brittle layer of glacier when ice beneath flows, NO deeper than 60 meters
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
What is an Arête?
thin ridge or spoke of rock carved between two parallel glacial valleys
What is a Cirque?
a bowl-shaped depression on side of mountain where glacial ice originated and flowed from
What is a Drumlin?
Deposit of sediment that was shaped into a tear-shaped hill by overrunning glacial ice
What is a Hanging Valley?
A shallow valley formed by a small glacial tributary as it joined with the large main glacier
What is an Esker?
former subglacial meltwater stream that was clogged with sediment as glacier melted
What is a Horn?
a tall, steep-faced mountain that formed as the result of converging cirques
What is a Kettle Lake?
water-filled depression formed when large junks of ice were left behind by receding glacier
What is an Outwash Plain?
surface in front of glacial tongue that is covered by water-reworked glacial sediment
What is a Tarn?
A lake inside of a cirque
What is a Terminal Moraine?
a ridge-like structure formed from debris that melts out of the ice at the toe of the glacier
What is a U-shaped Valley?
a glacially carved valley that is u-shaped in cross-section
What are Mega-Ripples?
meter-scale ripples, that consist of gravels moved during massive glacial meltwater floods
What is a Lateral Moraine?
rock debris that melts out of the glacier along the edges of its u-shaped valley
What is a Fjord?
Water-filled glacial valley due to rising sea level
What is a Medial Moraine?
rock debris that separates two parallel glacial ice tongues