EAR 101 Test 3
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EAR 101 Test 3
earth science syracuse university
EAR 101 Test 3 - Syracuse University
What is the law of superposition?
in an undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below
What are cross cutting relationships?
A rock is younger than any rock through which it cuts
What is a halflife?
The time required for half of a sample to decy
How can we determine half lives?
When the quantities of the parent and daughter are equal
What elements make useful geologic clocks?
What is the half life of 40K?
1.3 billion years
What is the half life of 238U?
4.5 billion years
How is 14C dating different from other forms of radiometric dating?
It has a half life 5,730, so it dates more recent things
What is the Shroud of Turin?
Cloth bearing image of man, used radioactive testing, from 1260-1390
How does radioactive 14C Form?
Produced in the upper atmosphere
Cosmic Rays shatter gas atoms releasing neutrons
What is the oldest rock on earth?
Precambrian, metamophic rocks
What is the oldest terrestrial mineral on Earth?
zircon---4.3 billion years
When did the Archean Period end?
2,500 million years ago
What is special about 543 million years ago?
The Paleozoic Era began
What is the age of the Earth?
4.6 billion years old
What is the half life of 14C?
Can we calculate the half life of a radioactive element without waiting for half of it to decay?
Yes, when the parent and daughter quantities are equal
What kinds of evidence makes us more convinced that geochronologic ages are correct?
What is significant about the Cambrian Period of geologic time?
It is the first evidence of abundant fossils
What is ground water?
Any water in saturation zone
What is a water table?
The upper limit of the saturation zone
What is the shape of the water table?
it replicates the topography of the land
What is permeability?
the measure of interconnected pore spaces, or ability of water to flow through pores
What is porosity?
The measure or water that soaks into the ground
What rocks have high porosity/permeability?
Coarse grained rocks
What is an aquifer?
Permeable rock strata that transmit groundwater freely
What is an aquiclude?
solid impermeable body that acts as a barrier to groundwater
What is a perched aquifer?
Small aquifer with a local water table that sits above the main aquifer
What are some problems with ground water?
-Use more then put in
How much fresh water does groundwater account for?
24% or 83.3 billion gallons per day
What is Karst?
Large areas that have been shaped by the dissolving power of ground water
What are speleotherms?
Dripstone features found in caverns
What is a stalagmite?
Speleotherms that form on the form reaching upward
What is a stalacite?
Speoleotherms that form on the ceiling coming down (think icicles)
What is a sink hole?
depression produced in a region where soluble rock has been removed by groundwater
How can you determine how fast groundwater moves?
Velocity= K* (h2-h1)/L
K-coefficient of permeability
What is Darcy's Law?
Showed velocity of groundwater flow is proportional to the slope
How do you find the hydraulic gradient?
What is the cone of depression?
The cone groundwater makes from wells
What is an artesian well?
A well drilled into an aquifer where the hydraulic head is higher than ground surface
What is a spring?
Where the water table intersects Earth's surface
What does the unsaturated zone mean?
A mix of air and water
What is a glacier?
A permanent mass of moving ice made of compressed snow on land
What are the different kinds of glacier?
How do glaciers move?
How many glacial period have there been in the past 1 million years?
How many glacial periods have been in the last 2 million years?
How do fossils and oxygen isotopes help in understanding glaciations?
Helps to tell times or warmth and glaciation
Normal to high levels of oxygen isotopes means glaciation
What are Arretes?
Sharp edged ridges
What are horns?
Sharp pyramid like peaks projecting above surroundings
What are Cirques?
Bowl shaped depressions with precipitous walls on 3 sides but are open downvalley
What are hanging valleys?
Where glaciers recede and valleys of tributary glaciers are left standing
What is a tarn?
Small lake from where a glacier used to be
What is a fjord?
flooded glacial valley
What are striations?
Grooves in the glacier
What is an erractic glacier?
"Rock out of place"
What is a kettle lake?
A large block left behind
What are Moraines?
glacial till deposited at the sides and ends of glaciers
What are Drumlins?
Whale shaped object composed of glacial till
What is a lateral moraine?
Parallel ridges of debris along the side of glaciers
What are medial morraine?
The middle part of the glacier
What are ground moraines?
At the base of the ice
What are the 3 cycles of the Milankovitch Cycle?
2. Change in tilt of Earth's rotational axis
3. Change in precession of Earth's rotational axis
What causes seasons?
Rotational axis tilt causes seasons
What is plastic flow?
Movement within the ice
What is basal slip?
Meltwater acts as a hydraulic jack and helps move ice over rock
What is Firn?
The granular recrystallized snow
How many kilometers are in a mile?
How many Liters in a gallon?
How many pounds in a kilogram?
How many inches in a centimeter?