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57 Cards in this Set
- Front
- Back
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How many years ago did the Earth begin?
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4.5 billion (Ga)
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How many years ago did life begin?
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3.5 billion (Ga)
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Geology includes the study of what?
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Natural hazards, land, earth materials, hydrologic processes, geologic processes
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Humans have been on earth for less than how many years?
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2 million (Ma)
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Where were the first fossils found?
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Australia and Africa
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What is relative time? "chronostratic"
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Geological subdivisions based upon relative age relationships (cretaceous, cambrian, cenozoic) usually on the basis of fossils; changes slightly around the world
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What is absolute time? "chronometric"
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Numerical ages (millions of years); most commonly obtained via radiometric dating methods
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What is the K-T boundary? When did it happen?
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The boundary between the Cretaceous (K) and Tertiary (T) periods; huge ice age and the extinction of dinosaurs; happened 65 million years ago
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What is cultural and environmental awareness?
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Uncovering the causes of current problems; we need to consider: political, economic, ethical, religious and aesthetic issues
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What do environmental ethics involve?
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Limitations on social and individual freedom of action
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What does a land ethic mean?
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We are responsible for our total environment
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What has resulted in an environmental crisis?
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Demands on diminishing resources by a growing population and the production of human waste
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What does our planet suffer from?
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Overpopulation, urbanization, and industrialization (deforestation, mining, development of water resources)
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What is the number one environmental problem?
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Increase in human population
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In 2000 what was the population number and what would it be in 2050?
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6.3 billion in 2000, 9-15 billion in 2050
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What are the 4 reasons for increase in population?
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Medicine, sanitation, agriculture, energy
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What is the environmental objective? What does it mean?
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Sustainability; sustain our resources so that they can continue to provide benefits for people and living things on the planet
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What is critical to solving environmental problems?
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Understanding earth's systems and their changes
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The Earth is an open system with respect to ? and a closed system with respect to ?
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energy; resources
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What can we do about hazardous earth processes?
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There have always been earth processes that are hazardous so the only thing we can do is recognize and avoid them
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What does understanding our environment require?
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Understanding of earth sciences and related disciplines
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What is the earth's mean diameter?
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12,742 km
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What can Earth's internal structure be divided by?
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Composition and density, behavior
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How thick is the inner core, is it solid or liquid, what is it made of, and what is the density?
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>1200 km, solid, 90% iron, 13
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How thick is the outer core, is it solid or liquid, what is it made of, and what is the density?
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>2200 km, molten, 90% iron, 10.7
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How thick is the mantle, is it solid or liquid, what is it made of, and what is the density?
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3000 km, mostly solid, iron and magnesium-rich silicates, 4.5
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What is the moho? What is the density?
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Boundary between mantle and crust; 2.8
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How thick is the aesthenosphere? What are 2 characteristics?
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300-400 km, molten and weak
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How thick is the lithosphere? What are 2 characteristics?
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100 km, cool and rigid
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What are 2 types of crust?
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Oceanic and continental
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How thick is the oceanic crust, what's the rock type, and how old is it? Less dense
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6-7 km, basaltic, less than 200 million years old (Ma)
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How thick is the continental crust, what's the rock type, and how old is it?
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35 km, heterogeneous, several billion years old (Ga)
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What is seismology?
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Study of earthquakes and passage of seismic waves through the earth
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What is the focus?
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Location where earthquake energy is first released within earth
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What is the focal depth?
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Depth of the earthquake focus
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Are P-waves fast or slow and travel through liquid or solid?
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Fastest, travel through both liquid and solid; similar to sound waves in the air
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Are S-waves fast or slow and travel through liquid or solid?
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Slower, travel through solids only; none are known to have traveled through Earth's core
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What marks the moho?
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The difference in speed of P-waves in the crust (6.5km/s) and upper mantle (8 km/s)
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When do P-waves slow down?
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When traveling through liquid
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What are tectonics?
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Large-scale geologic processes that deform Earth's lithosphere
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What do plate tectonics produce and what are they driven by?
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Landforms (ocean basins, continents, mountains); force deep within the Earth
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What are plate tectonics associated with?
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Creation, movement, and destruction of lithospheric plates
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What is the tectonic cycle?
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Process of continuous recycling
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What is continental drift and who came up with the theory?
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Lithospheric plates move over the asthenosphere, carrying the continents with them; Alfred Wegener
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When did the breakup of Pangaea start?
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180 million years ago (Ma)
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Plates move about how many cm/year?
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1-15
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How can rigid continents move relative to each other and how can ocean floors change their shape?
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Plate boundaries
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What are the 3 types of plate boundaries?
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Divergent, convergent, transform
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What is divergent boundary?
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Where new lithosphere is being created and neighboring plates move away from eachother
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What is convergent boundary?
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Where two plates collide
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What is transform boundary?
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where two plates move past one another and crust is neither destroyed nor created
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What is triple junction?
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When 3 plates share common boundaries (Japan)
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What are mid-ocean ridges or spreading ridges?
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New crust is formed, continually adding to the edge of the lithosphere
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What are the 4 things for evidence of sea floor spreading?
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continents fit together, seafloor mapping, paleomagnetism, dating volcanic rocks
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What is paleomagnetism?
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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
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What does magnetic reversal mean?
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Earth's magnetic field has been reversed in the past; scientists have mapped out reversals through time
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What are hot spots?
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Volcanic centers and uplift resulting from hot material produced deep in the mantle
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