Quiz 5 for martin's class
If 16 radioactive parent atoms decayed to half of their original number after one year, how many radioactive parent atoms would be left after two years?
4
Metamorphic rocks are exposed at the Earth's surface mainly in
Current of former mountain belts, continental shields, regions of deeply incised crust
The rate of decay (dP/dt) of a population of radioactive parent atoms __________ over time.
Decreases
Where is magma generated as a result of increased temperature?
Hot spot
QUIZ FIVE
Magma, dating, formations
What makes the isotopes of a given element different from one another?
Number of neutrons
The half-life of carbon-14 is about 6,000 years. Assume that a sample of charcoal was formed by burning of living wood about 12,000 years ago. How much of the original carbon-14 would remain in the wood today?
One-fourth
__________ dating is the task of placing rock units and geologic events in their proper sequence
Relative
The volcano shown is
Stratovolcano
Which of the following regions in the US is most at risk for violent volcanic eruptions
The Cascade Mountains of California, Oregon and Washington
What is a caldera?
The depression
What is a dike?
Vertical band
Do nutrients move around the biosphere?
YES
The dark rack the arrow is pointing to was broken off from a magma conduit wall and incorporated in to magma that subsequently solidified into the surrounding lighter colored igneous rock. Thus, the dark rock would be
Zenolith
The feature to which the arrow in the figure below is point is
a dike
The presence of stishovite, coesite, and tektites in a rock would be evidence for the past existence of
a shock metamorphism as from a meteorite impact
An unconformity represents
a time gap in the geological record
The lava flow shown in the foreground of the photograph below is an example of
aa
The bold line shown in the sedimentary rock package shown in the figure below represents
an angular unconformity
The principle of Inclusions states that
an inclusion is always older than the rock matrix that encloses it.
In a sequence of undeformed sedimentary rock layers, the youngest rock layer would be
at the top
Why would the contact between sedimentary rock and high grade metamorphic rock represent an unconformity?
because sedimentary rocks form at the Earth's surface and metamorphic rocks form deep in the Earth; for sedimentary rocks to be in contact with metamorphic rock, the rock burying the metamorphic rock must have been removed
Why would radiometrically dating a mineral in the clast of a sedimentary rock not yield the age of formation of the sedimentary rock?
because the date would give the age of the older source rock from which the sediment was derived
What is a sill?
dark band of rock
Radiometric dating can provide the numeric mineral age if the mineral...
hasn't lost or gained parent/daughter atoms after the mineral formed
Why does magman viscosity increase the likelihood of an explosive eruption
higher viscosity magmas tend to be hotter than more fluid magmas, giving viscous magmas more energy for explosions
What is The Principle of Uniformitarianism
holds that the same geologic processes we recognize in action today have been operating throughout the Earth's history to create the features we see in the geologic record
The principle of Uniformitarianism
holds that the same geologic processes we recognize in action today have been operating througout the Earth's history to create the features we see in the geologic record
Changes in the number of neutrons in an atom
may cause the atom to become unstable and undergo radioactive decay
Within a sequence of undisturbed sedimentary rock layers where would the oldest layer be located
on the bottom
WHich of the following igneous features is not associated with violent volcanic eruptions?
pillow lavas
Why are sedimentary rocks typically deposited in a horizontal orientation?
sediments tend to slide down steeply dipping surfaces but can more easily accumulate on horizontal surfaces
Cinder cones...
tend to be smaller than shield volcanoes or stratovolcanoes
How would a metamorphic quartzite differ from a sedimentary quartzite (i.e. quartz sandstone)
the quartz grains in the metamorphic quartzite would be more tightly interlocking, leaving less pore space
The vast expanses of 150 to 80 million year old granite that form the core of the Sierra Nevada Mountains in eastern California are products of
the subduction of the Farallon plate beneath North America
What do the volcanoes, Mount St. Helens, Vesuvius, Krakatau, Lassen Peak, and Mount Pinatubo have in common?
they all have erupted explosively
The vast expanses of 150-80 million year old granite that form the core of the Sierra Nevada Mountains in eastern California are products of
transform plate boundary motion between the North American and Pacific plates