Exam 1 Flashcards
Geology
The study of Earth
Geologist also study…
Rocks, water, soil, & the atmosphere
Natural Disaster
A naturally occurring event that has a negative effect on humans
What makes a natural disaster?
A disaster that happens in nature by nature
What makes a natural event a disaster?
The destruction of homes and loss of lives
“Great” Natural Disaster
A natural disaster that kills 1,000s of people & require international aid
Why are “Great” Natural Disasters increasing?
Because Earth’s population is increasing
“Return Time”
The average # of years between same-sized events
Gas giant planets
Large, low density balls of gas
Terrestrial planets
Small, more dense balls of gas
Earth’s constant changing surface
.Internal heat from radioactive decay
.K, Th, & U isotopes
.”Tectonic system”
.”Hydrologic system”
Scientific Method
Analyze scientific problems in a way that leads to verifiable results
Hypothesis
A possible explanation, involving naturally occurring processes
Theory
Scientific ideas that are tested and could be proved wrong
Law
Scientific ideas that are absolutely correct
Uniformitarianism Principle
.Traditional: The present is the key to the past
.”Actualism: The laws of nature do not change through time
Application of uniformitarianism
Traditional
Principle of Cross-Cutting Relationships
Any geologic phenomenon that cross-cuts something is younger than whatever it is cross-cutting
Hydrologic System
Water in solid, liquid, & gas form
Tectonic System
Moving plates
Tectonic plates control
Mountain ranges, position of continents, earthquakes, & volcanoes
Seismologists
Study earthquakes
Volcanologist
Study volcanoes
Scientific Method Steps
- Identify problem
- Collect data
- Propose hypothesis
- Test hypothesis
Everyday Theory
A “hunch”
4 common elements on Earth
Iron, Oxygen, Silicon, & Magnesium
Mineral
Solid substances of specific chemical composition, w/ arranged atoms in an orderly pattern
Rock
Aggregates of minerals
3 types of rocks
Sediment, Metamorphic, & Igneous
Igneous rock
.Granite
.Intrusive/Extrusive
.Solidification (Crystallized) from magma/Consolidation
Sedimentary rock
.Conglomerate .Metamorphism .Lithification .Deposited by water, wind, glaciers, or landslides .Compacted/cemented .Forms near the surface
Metamorphic rock
.Former igneous/ sedimentary rock
.Changes due to high temperature and pressure
.Compresses
.Foliation/banding
Intrusive
.aka plutonic
.Rocks forming deep underground
Extrusive
.aka volcanic
.Rocks forming from lava cooling quickly
Foliation
Pressure squeezes mineral crystals into layers
Banding
Separation of minerals into light & dark layers
Silicate minerals
.Minerals that contain silicon & oxygen and aluminum of iron
.Found in the Earth’s crust
Mohorovicic discontinuity
Boundary between crust & mantle, where velocity of earthquakes waves change
Crust
.Outermost layer
.Continental crust less dense than oceanic crust
Mantle
.Below the crust to 2900km
.More dense
.Composed of silicates minerals w/ more Fe & Mg
Core
.Most dense
.Composed mostly of Fe & no silicates
.2900km to the center
Atmosphere
Mostly gas
Hydrosphere
Water originated from volcanic activity
Lithosphere
.Solid, rigid and brittle
.Crust & upper mantle
.Thickness
Asthenosphere
.Upper mantle
.Ductile rocks
.Deform easily
Mesosphere
.Middle to lower part of mantle
.More solid
.Somewhat ductile
.Temperature decreases with height
Outer core
Liquid
Inner core
Solid
Radioactive decay
Earth’s internal heat source
Earth’s energy sources
.Sun
.Radioactive decay
.Gravity
.Impact by extraterrestrial objects
Seismic wave refraction
.Light travels more slowly
Seismic wave reflection
.Light travels faster
Hydrologic system
.Erosion & deposition by water
.Primary source: sun & gravity
Tectonic system
.Plates moving on Earth’s surface
.Primary source: radioactive decay
Mars
.Has no tectonic plates
.Volcanoes are not common
Oceanic crust
.Composed of volcanic igneous rock aka basalt
.Created by sea floor spreading
Continental drift
.Alfred Wegener (1914)
.Continents were united to form pangaea
Wegener’s evidence
.Fossil distribution .Ancient glacier .Rocks .Fit of continents .Paleoclimate distribution
Wegener’s evidence rejected
Lack of a mechanism
Plate tectonic theory
.Lithosphere- rigid plates which move relative to each other
.Asthenosphere- plastic, allowing movement of the lithosphere
Principle of superstition
Older layers are on the bottom
Fixed continent
Wandering poles & don’t move
Drifting continent
Fixed pole & continents move
Seafloor
.Igneous & thin layer of sediments
.Gives clues as to how plates move
Mid-ocean ridges
High heat flow & volcanic activity
Ocean ridge spreading rapidly
Longer and wider
Pillow lava
Fount at the bottom of mid-ocean ridges
Sea-floor magnetic anomalies
.Parallel bands of reversed & normal polarity
.Found across mid-ocean ridges
.Calculate the rate of plate movement
Global Positioning System
Helps us understand plate movement
Oceanic plate
thin, dense
Continental plates
thicker, less dense
Isostasy
An idea that the asthenosphere deforms plastically to accommodate the plates
GPS
Precisely calculate rate & direction of movement
Guyots
.Seamounts
.Flat-topped ones
Paleomagnetism
Preserves Earth’s magnetic field in iron-rich rocks
Magnetite
.Common in igneous rocks
.Can be found in sedimentary rocks where grains align
Poles of continents
Varied by continent
3 types of plate boundaries
Divergent, convergent, & transform
Majority of divergent plates
Mid-ocean ridges
mid-ocean ridges features
Increase in age & decrease in temperature & volume as you move away from the center
Continental rifting, less common why?
They eventually become a mid-ocean ridge
Triple-junction rift
3 armed rift (shaped like a “Y”)
Aulacogen
1 failed arm in a triple-junction ritft
East African rift
Is a triple-junction rift
Basin & range area
.Rifting at 1-5 cm/yr
Name of Basin & range area
Presence of “fault block mountains & valleys
Subduction zone
Oceanic plate is pushed beneath another plate
Where are subduction zones?
Deep ocean trenches
Plates involved in subduction zones
Continental and oceanic
Pattern of earthquake distribution at subduction zones
Deep earthquakes
Focus of an earthquake
Exact location below the surface measure in km
Volcano activity at subduction zones
Magma rises towards the surface
Volcanic arc
A chain of volcanoes overridden by a continental plate
Island arc
A chain of volcanoes overridden by a oceanic plate
Japan
.Oceanic plate & oceanic plate
.Island arc
Andes
.Continental plate & oceanic plate
.Volcanic arc
Cascade range
Volcanic arc
Pacific ocean aka “Ring of Fire”
subduction zones surround it
Continental & continental plates
.No subduction
.Highly deformed rocks of mountain ranges form
The Himalayas
Continental & continental plates
What are common at continental/ continental plates
Because the earthquakes are shallow
Transform plates
Move past each other
Name: transform plates
It causes faults
Most common type of transform boundary
.Mid-ocean ridges
.Contact between 2 plates
Mantle plume
A long-lived fixed “hot spot” in the mantle
Why do mantle plumes rise?
Because if comes from the core-mantle boundary
No silicate material
The core
Subduction zones properties
.Deep focus earthquakes
.Volcanic arc
.Deep ocean trench
Tectonic system primary source
heat from radioactive decay from unstable isotopes