Test 2 Flashcards
- Viscosity of the magma is controlled by?
temperature and silicon content of the magma
The shape of shield volcanoes is a function of?
lava viscosity
Why do composite volcanoes consist of alternating lava and pyroclastic layers?
Composite cones are created by a mixture of explosive activity and lava flows.
A lahar is produced when?
ash and other pyroclastic ejecta become saturated with water
Why is topographic monitoring sometimes useful in forecasting a volcanic eruption?
A volcano sometimes swells as lava moves into the edifice.
Why is the geologic history of a volcano important in hazard prediction?
The geologic history reveals the frequency and style of eruptions.
Seismic activity serves as a tool of volcanic forecasting because
moving magma causes earthquakes
Which volcano represents the greatest hazard to the area around Tacoma in Washington State?
Mt. Rainier
What is the name for the basaltic lava flow that has a ropy, folded surface?
pahoehoe
Yellowstone, in Wyoming, is an example of a
Caldera
- Why did extensive flooding occur upstream of St. Louis during the 1993 Mississippi River flood?
Floodwalls protecting St. Louis caused a bottleneck in the river’s flow.
The portion of rainfall that flows off the land and directly into a river is called
runoff
What is river base level?
the lowest level to which a river may erode
The suspended load of most rivers consists mostly of
silt and clay
If a stream channel is of constant width and depth, how must increased discharge be accommodated?
increased velocity
The Ventura Beach RV Resort was flooded because
it was constructed in an unrecognized distributary channel that became active
The total load of sediment that a river carries in a given period of time is called
Capacity
Why might logging of a drainage basin change the slope of the river?
Increased sediment load causes the river to steepen its gradient to transport more sediment.
What type of river channel is characterized by multiple channels and gravel bars?
Braided
How do point bars and cut banks differ from one another in a stream system?
Cut banks are sites of erosion, while point bars are sites of deposition.
What is the best description of the “10-year flood”?
a flood that has a 10% chance of occurring on any given year
The degree of urbanization can amplify flooding primarily by
a high percentage of impervious cover and the percentage of area served by storm sewers
In what way can structural control of floods actually increase flood damage?
by encouraging development on the floodplain
Which of the following particles is the MOST likely to be eroded from a stream bed?
Sand
Which of the following is MOST likely to be transported as suspended load?
Clay
Which of the following equations for stream discharge is correct? Discharge = length x velocity Discharge = Depth x velocity Discharge = width x depth x velocity Discharge = volume x velocity x distance
Discharge = width x depth x velocity
Because of undercutting action, waterfalls…
Retreat upstream
A stream that has a smoothly curving longitudinal profile representing a balance between erosion and sedimentation is referred to as a __________ stream.
Graded
. A drainage divide is a….
topographic high that separates stream systems
A tree-like drainage pattern is known as
Dendritic
In 1908, the Tunguska River Valley in Siberia experienced
an aerial burst of a meteor
A meteoroid is
a small particle of an asteroid
A meteor is
a meteoroid that has entered the Earth’s atmosphere
A meteorite is
a meteoroid, asteroid, or comet that strikes the Earth’s surface
In 1994, the comet Shoemaker-Levy 9 collided with
Jupiter
A meteorite impact crater can be distinguished from a volcanic crater through the presence of
high pressure metamorphic minerals
Why are impact craters more common on the Moon and Mars than on Earth?
the Moon and Mars have thinner atmospheres
The Cretaceous-Tertiary mass extinction was apparently caused by a meteorite that struck
Yucatan Peninsula
What element was found to be enriched in a thin clay layer marking the Cretaceous-Tertiary boundary at several sites around the world?
iridium
How big was the meteorite that apparently caused the Cretaceous-Tertiary mass extinction?
10 km
Archaeopteryx was an important discovery for its time because
It was transitional between feathered dinosaurs and modern birds
Which of the following represents the longest time period
Precambrian
The ____________ was an era dominated by the dinosaurs
Mesozoic
Age defined by radiometric dating is often referred to as ________________age.
Absolute
A rock formed with 1,000 atoms of a radioactive parent element, but only contains 250 radioactive parent atoms today. If the half-life is 1,000,000 years, how old is the rock?
2,000,000 years
Mammals become abundant in the ______________era.
Cenozoic
The study of faunal succession allows ___________
matching of similarly-aged rocks from different outcrops
A cladogram is a ______________________.
a diagram showing relationships among organisms.
Which of the following does NOT describe an Index Fossil
Answer
Only preserved in one area of the Earth
Easily identifiable
Existed for only a short time before going extinct
Commonly preserved in the rock dating to the time period in which they existed.
Only preserved in one area of the Earth
Stromatolites are some of the earliest fossils dating to the _____________________.
Precambrian
What factor has contributed to the drying up of streams and the intrusion of salty groundwater in the Long Island area?
overpumping of groundwater
If water is so abundant on Earth, why are water resources such a big concern?
Water resources are not necessarily where humans need them and when they need them.
Why is sediment yield an important consideration in a discussion of water supplies?
Sediment is a common water pollutant.
The boundary between drainage basins is called the
drainage divide
Vegetation decreases runoff by
intercepting rainfall and slowing its fall to the ground
Which of the following would likely serve as an aquitard?
Silt
An artesian well is one that
Emits water without pumping
The rate of groundwater flow is proportional to the
the hydraulic gradient and hydraulic conductivity
Why has water quality degraded in the Edwards aquifer?
The aquifer is recharged by rivers flowing into karst limestones.
Why is karst topography a concern for groundwater quality?
Waste disposed in karst areas can easily infiltrate into the ground.
How did Hurricane Floyd contribute to dramatic water pollution in North Carolina?
Intense rain and river flooding caused poorly sited pig farm waste lagoons to overflow.
The level of decaying organic matter in water is indicated by what measure?
biochemical oxygen demand
What measures have largely eliminated waterborne diseases in the United States?
separation of sewage and drinking water
The biomagnification of mercury occurs as mercury moves through
the aquatic food chain
Which of the following would be considered a point source of pollution?
industrial wastewater discharge
What happened to the Cuyahoga River in Cleveland in 1969?
it caught fire
Saltwater intrusion results from
overpumping of groundwater
Acid mine drainage is a problem because
the acid water may mobilize hazardous heavy metals
In what type of rock do caves mostly form?
Limestone
How fast does most groundwater move in aquifers?
A few centimeters per day
How many NEOs (Near Earth Objects) have been discovered so far?
13,850
How many of these are considered PHAs (Potentially Hazardous Asteroid)?
1,681
What is the threshold size of an object that would produce a catastrophic disaster if it struck the earth?
1 kilometer (1,000 meters)
How often is it expected that an asteroid or comet with a diameter greater than 1km strike the earth?
On average, about every 1 million years.
Why would collision with such an object produce more than just a local effect?
A collision that size would affect the climate of the planet for many years.
Fragmented
rock, ash &
dust is?
Pyroclastics
3 types of volcano types are?
shield, composite, and cinder
High viscosity lavas dont do what?
flow far from eruption center
Most of the gases in magma are?
H20 (water vapor), and C02
The three types of magma are?
Basaltic, Andesitic, and Rhyolitic
What type of volcano can for abruptly?
Cinder Cones
Gas cavities from escaping dissolved gases are?
Vesicles
Extremely vesicular volcanic rock, and very silica rich
Pumice
any flowing body of water. A stream
is a body of water with a current, confined within a bed
and stream banks
Stream
3 basic parts of a stream are..
Valley, channel, and floodplain
Low sediment load, and low velocity streams are….
Meanders
High sediment load, and high velocity streams are…
Braided Streams
What type of stream can form oxbow lakes?
Meanders
A stream whose channel divides into an interlacing network of channels, which then rejoin in a pattern resembling braids of hair.
Braided Stream
Why are floodplains so important?
They form natural levees
: The volume of water passing through a given
location of a river per unit of time is a rivers…
Discharge
What is the Archaeopteryx?
Link between feathered dinosaurs and modern birds
The order of events in geology is the…
Relative Time
Radio active varieties of an element are…
Isotopes
This is used to date a particlular rock strata based on sequence of living organisms
fossil assemblage
These are geological records of biological activities
Trace Fossils
Coprolites are..
fossilized droppings
What were some of the first multi-cellular organism, and were also once widespread?
Stromatolites
the most rapid and widespread diversification of life in Earth’s
history, known as the
Cambrian explosion
most of the hoover damns power goes where?
california
the study of water movements on,
over, and under the Earth’s surface; how this flow
responds to natural and human induced change
Hydrology
50% of water usage can be attributed to what?
Industy
a sinking of the
Earth’s surface caused by loss of
aquifer porosity
subsidence
