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57 Cards in this Set

  • Front
  • Back
How many years ago did the Earth begin?
4.5 billion (Ga)
How many years ago did life begin?
3.5 billion (Ga)
Geology includes the study of what?
Natural hazards, land, earth materials, hydrologic processes, geologic processes
Humans have been on earth for less than how many years?
2 million (Ma)
Where were the first fossils found?
Australia and Africa
What is relative time? "chronostratic"
Geological subdivisions based upon relative age relationships (cretaceous, cambrian, cenozoic) usually on the basis of fossils; changes slightly around the world
What is absolute time? "chronometric"
Numerical ages (millions of years); most commonly obtained via radiometric dating methods
What is the K-T boundary? When did it happen?
The boundary between the Cretaceous (K) and Tertiary (T) periods; huge ice age and the extinction of dinosaurs; happened 65 million years ago
What is cultural and environmental awareness?
Uncovering the causes of current problems; we need to consider: political, economic, ethical, religious and aesthetic issues
What do environmental ethics involve?
Limitations on social and individual freedom of action
What does a land ethic mean?
We are responsible for our total environment
What has resulted in an environmental crisis?
Demands on diminishing resources by a growing population and the production of human waste
What does our planet suffer from?
Overpopulation, urbanization, and industrialization (deforestation, mining, development of water resources)
What is the number one environmental problem?
Increase in human population
In 2000 what was the population number and what would it be in 2050?
6.3 billion in 2000, 9-15 billion in 2050
What are the 4 reasons for increase in population?
Medicine, sanitation, agriculture, energy
What is the environmental objective? What does it mean?
Sustainability; sustain our resources so that they can continue to provide benefits for people and living things on the planet
What is critical to solving environmental problems?
Understanding earth's systems and their changes
The Earth is an open system with respect to ? and a closed system with respect to ?
energy; resources
What can we do about hazardous earth processes?
There have always been earth processes that are hazardous so the only thing we can do is recognize and avoid them
What does understanding our environment require?
Understanding of earth sciences and related disciplines
What is the earth's mean diameter?
12,742 km
What can Earth's internal structure be divided by?
Composition and density, behavior
How thick is the inner core, is it solid or liquid, what is it made of, and what is the density?
>1200 km, solid, 90% iron, 13
How thick is the outer core, is it solid or liquid, what is it made of, and what is the density?
>2200 km, molten, 90% iron, 10.7
How thick is the mantle, is it solid or liquid, what is it made of, and what is the density?
3000 km, mostly solid, iron and magnesium-rich silicates, 4.5
What is the moho? What is the density?
Boundary between mantle and crust; 2.8
How thick is the aesthenosphere? What are 2 characteristics?
300-400 km, molten and weak
How thick is the lithosphere? What are 2 characteristics?
100 km, cool and rigid
What are 2 types of crust?
Oceanic and continental
How thick is the oceanic crust, what's the rock type, and how old is it? Less dense
6-7 km, basaltic, less than 200 million years old (Ma)
How thick is the continental crust, what's the rock type, and how old is it?
35 km, heterogeneous, several billion years old (Ga)
What is seismology?
Study of earthquakes and passage of seismic waves through the earth
What is the focus?
Location where earthquake energy is first released within earth
What is the focal depth?
Depth of the earthquake focus
Are P-waves fast or slow and travel through liquid or solid?
Fastest, travel through both liquid and solid; similar to sound waves in the air
Are S-waves fast or slow and travel through liquid or solid?
Slower, travel through solids only; none are known to have traveled through Earth's core
What marks the moho?
The difference in speed of P-waves in the crust (6.5km/s) and upper mantle (8 km/s)
When do P-waves slow down?
When traveling through liquid
What are tectonics?
Large-scale geologic processes that deform Earth's lithosphere
What do plate tectonics produce and what are they driven by?
Landforms (ocean basins, continents, mountains); force deep within the Earth
What are plate tectonics associated with?
Creation, movement, and destruction of lithospheric plates
What is the tectonic cycle?
Process of continuous recycling
What is continental drift and who came up with the theory?
Lithospheric plates move over the asthenosphere, carrying the continents with them; Alfred Wegener
When did the breakup of Pangaea start?
180 million years ago (Ma)
Plates move about how many cm/year?
How can rigid continents move relative to each other and how can ocean floors change their shape?
Plate boundaries
What are the 3 types of plate boundaries?
Divergent, convergent, transform
What is divergent boundary?
Where new lithosphere is being created and neighboring plates move away from eachother
What is convergent boundary?
Where two plates collide
What is transform boundary?
where two plates move past one another and crust is neither destroyed nor created
What is triple junction?
When 3 plates share common boundaries (Japan)
What are mid-ocean ridges or spreading ridges?
New crust is formed, continually adding to the edge of the lithosphere
What are the 4 things for evidence of sea floor spreading?
continents fit together, seafloor mapping, paleomagnetism, dating volcanic rocks
What is paleomagnetism?
Study of magnetism of rocks at the time their magnetic signature formed; earth has a magnetic field that can be represented by a dipole magnetic field with lines of force connecting the north and south poles
What does magnetic reversal mean?
Earth's magnetic field has been reversed in the past; scientists have mapped out reversals through time
What are hot spots?
Volcanic centers and uplift resulting from hot material produced deep in the mantle