Which statement best describes science?
Science is the process of discovery
Which of the following is not a characteristic of scientific explanations
They are able to answer all questions
Scientific results are unpredictable and are mainly determined by the personal views of the scientists.
False
Once a scientific explanation has been established it never needs to be changed
False
What distinguishes science from non-science?
Science is based on empirical observations
Which type of plate motion is characteristic of a convergent boundary?
Plates move toward one another
Which type of plate motion is characteristic of a divergent boundary?
Plates move away from one another
Which type of plate motion is characteristic of a transform boundary?
Plates move past one another
What is the proper order of Earth's compositional layers from the interior to the surface?
Core, mantle, crust
At least three seismograph stations from three different locations are required to determine the epicenter of an earthquake
True
A Richter magnitude 6 earthquake has about double the ground motion compared to a Richter magnitude 5 earthquake
False
A magnitude 8.0 earthquake will always cause more damage and loss of human life than a magnitude 7.0 earthquake
False
P and S waves are both body waves
True
Magnitude is a measure of the size of an earthquake while intensity deals with the earthquake's effect on humans
True
This earthquake-generated hazard can occur when seismic waves shake saturated soils
Liquefaction
What is the difference between earthquake magnitude and intensity?
Magnitude measures earthquake size, intensity documents damage
Which volcanoes are most likely to explode and why?
Strato- because the magma is more viscous than in shield volcanoes
Shield volcano
Broad gentle slopes, low viscosity (basalt)
Strato-volcano
Steeper slopes, explosive tephra, magma is andesite
This forms mostly from ash deposits
Cindercone
This is composed of multiple layers of ash and rock
Strato-volcano
Which geologic time principle places events in order based on their position?
Relative time
When was the extinction of the dinosaurs?
66 million years ago
What year was the oldest fossil found?
500 million years ago
When was the Earth formed?
4.6 billion years ago
What are the 2 types of surface waves?
Rayleigh waves and Love waves
Rayleigh waves
Vertical movement of surface
Love waves
Produced horizontal movement
What are the Eons of geologic time?
Archean, Proterozoic, and Phanerozoic
What are the Eras of geologic time?
Paleozoic, Mesozoic, and Cenozoic
How long ago was Archean?
5000 million years ago
How long ago was Proterozoic?
2,500 million years ago
How long ago was Phanerozoic
541 million years ago
How long ago was Paleozoic?
541-252 million years ago
How long ago was Mesozoic?
252-66 million years ago
How long ago was Cenozoic
66-0 million years ago
What are the two mass extinction that occurred in geologic time?
Permian-Triassic and Cretaceous-Tertiary extinction
Permian-Triassic
Elimination of over 95% marine and 70% of terrestrial animals.
Cretaceous-Tertiary
Elimination of approximately 80% of all species of animals. Includes the extinction of dinosaurs. Mostly birds survived.
How long ago are the fossils traced back?
500 million years ago
What is dirt made up of?
45% mineral fragments, 25% water, 25% air, and 5% organic materials
Why is soil important?
Allows us to grow crops, water filtration, help with flooding and more
What is weathering?
Physical, chemical, and biological breakdown of rocks and minerals
Physical Weathering
Disintegration of rocks and minerals into smaller pieces
Unloading
Erosion strips away overlying material
Wedging (frost)
Process by which water seeps into cracks in a rock, expands on freezing and thus enlarges the cracks. The process repeats
Wedging (Crystal Growth)
Growth of salt crystals in small rock openings
Chemical Weathering
Decomposition of rocks due to the chemical breakdown of minerals
Dissolution
Minerals in a rock are dissolved by water (ex: acid rain)
Hydrolysis
A chemical reaction in which water reacts with a compound to produce other compounds
Oxidation
Oxygen reacts with iron and other metals to form new mineral compounds (ex: rust on your car)
Microscopic Biological Weathering
Primarily caused by decomposition of material that converts solid material to gases with or without water
Macroscopic Biological Weathering
Includes the actions: Plant roots, animal burrows, termites, and other boring organism
Rock composition
Weathering is faster in rocks composed of weaker material or material that is easily converted to weaker material (such as feldspars) and rocks made up of minerals that dissolve in water (salt). Slower in rocks made up of resistant materials (quartz)
Rock Properties
Weathering is faster in rocks that allow air and water (porous, fractured). Fractures are natural weathering surfaces.
Name the layers in Soil
O: Organic debris, dead leaves, and plant, and animal remains, makeup 30% of this layer. A: Topsoil, dark organics mixed with mineral grains by organic activity E: Subsurface layers that have lost most of their minerals. Can be embedded in A horizon or replace A horizon B: Subsoil, accumulation of iron, aluminum, and clay leached down from the A and E horizons C: Weathered, lowest rock layer, partially broken down the bedrock
Mass wasting
The downslope movement of materials under the influence of gravity (landslides)
What are some factors influencing Slope failures?
Gravity moves materials down a slope (Gravity has 2 components: parallel to the slope and perpendicular to the slope)
Friction acts to prevent or movement of material down a slope
Steeper slopes are more likely to fail
What happens when there are too much water?
promotes instability
very wet sediment flows like a liquid
Excess water reduces cohesion between grains and allows them to move more freely
Adds weight to the slope
Water supports some of the weight of overlying materials
How can we minimize slope failures?
Improve slope drainage
Attach the slope material to bedrock with physical restraints
Build a restraining wall
Urban planning
Careful of deforestation
What types of slope failures are there?
Rockfall, Rockslide, Slump, and Creep
Rockfall
A descent of loose rocks
Rockslide
Large-scale movement of rocks down a hill
Slump
Movement of material down a slope on a curved surface
Creep
Slow, downslope movement of soil and earth materials
Why are Rivers important?
Good for farming, soil has moisture/sediment, river deposit silt for goods, easy transportation for goods, good for hunting, and hydroelectricity
Stream
Any flow of water through a channel (defined by its banks), from the smallest creek to the biggest river
Hydrologic Cycle
Water moves in and around the earth system, changing from one physical state to another
Where do streams come from?
Comes from uphill and orginates from a springs
What is an aquifer?
A body of rock and sediment that's saturated - water is in it and around it. And water can move through it
Where does water go?
Regardless of where or how it starts, streams always flows downstream and empty into another body of water (stream, lake, ocean, reservoir, wetland)
What controls the amount of water in a stream channel?
The size of the area it drains and the average precipitation over the area
Drainage Basin
The area drained by a stream and its smaller streams (tributaries)
Drainage Divides
Found along the high ground separating drainage basins
Dendritic pattern
Develops on relatively uniform bedrock
Trellis pattern
Develops in areas of alternating weak and resistent rock
Rectangular pattern
Develops on highly jointed bedrock
Radial pattern
Develops on isolated volcanic cones or domes
Gradient
The slope of the stream. it is the change in elevation of the stream over a horizontal distance
Channel Roughness
Rocky banks and channels -> becomes less rock, changing to gravel, the sand, then fine-grained silt and mud
Wetted Perimeter
Height + Length + Height
Cross-sectional Area
Height x Length
Hydrolysis Rate
Height x Length / Height + Length + Height
Drainage Rate
Volume/Time = m^3/seconds = Height x Length x Volume
Stream Discharge
Volume of water that passes a given point in one second (Width x Depth x Velocity = ... m^3)
Groundwater
Water held underground in the soil or in pores and crevices in rock
What are some potential threats to the water supply?
Fertilizer, oil spills, pesticides, bacteria, usage, chemical spills, gasoline stored underground, but mostly caused by human activity
How does water get underground?
The amount of groundwater at any location depending on porosity and permeability materials beneath the surface
Porosity
The proportion of a material that is made up of spaces (Sand, gravel)
Permeability
The capacity of water to flow through earth materials (coffee beans)
Specific yield
The groundwater that can drain from a rock or sediment
Specific retention
Water on the surface of grains that will not flow through the material
Aquitards
Low permeability materials such as clay, shale, or unfractured igneous or metamorphic rock that act as a barrier (ziplock bags)
Unconfined aquifer
Open to Earth's surface and to infiltration
Confined aquifer
Overlain by less permeable materials
Water Table
The level below which the ground is saturated with water
Gaining Streams
Gain water from an area with a high water table (form of discharge not recharge)
Losing Streams
Flow overground in dry areas and lose water into the groundwater supply
Groundwater overdraft
The supply cannot replenish as fast as we extract it for human use which causes a decline in the water table
Pumping Groundwater
Trying to pump groundwater is like sucking up a spilled drink from a table. No matter how big a straw you use, most of the drink stays on the table top