Planet Earth Midterm
Radiometric dating of a magnetic anomaly stripe of rock that is 225 km away from the mid-ocean ridge axis gives an age of 9 million years. Assuming a constant rate, seafloor spreading in this area occurs at a rate of
2.5 cm per year
The chain of Hawaiian islands can be used to calculate the rate of movement of the Pacific Plate over the last few million years. The island of Hawaii currently sits on the hot spot and is therefore 0 million years old. The island of Oahu used to sit on the hot spot and is now approximately 360 km away from the hot spot, to the northwest. If the average plate motion is 9 cm/yr, how old is Oahu (Remember to convert your units properly!)
4 my (Rate = distance/time, so 9 cm/yr = 360 km/x years. Now, km needs to be converted to cm. Each km is 1000 m. Each meter is 100 cm.) pg 109
Choose statements true of transgression and regression. Sort the statements as being true of either transgression or regression.
Transgression- Coastline migrates inland, position of beach moves inland, involves a relative rise in sea level regression- involves a relative fall in sea level
Sort these mountain chains based on what caused them to form.
continental collision- alps, Himalayas, Appalachian mountains other- Rocky Mountains
Contrast continental collision and volcanic island arc formation. Sort properties of each.
continental collision- involves continental crust Volcanic Island Arc Formation- involves volcanism, involves oceanic crust, involves subduction
igneous rock that has a medium-gray, fine-grained groundmass with large crystals of plagioclase
could logically be a porphyritic andesite.
Ripple marks, dunes, and cross bedding are useful indicators of
current direction
Which part of the Earth's magnetic field does this tilt represent?
inclination
Scientific cosmology
includes the Big Bang theory.
age of oceanic crust
is least at the mid-ocean ridge and greatest farthest from the ridge.
Brittle deformation
is less likely to occur deep in the crust than at the surface.
The geothermal gradient
is the rate of change in temperature with depth in the Earth.
Continental crust
is thicker than oceanic crust.
Magnetic reversals
reflect changes in the direction of the flow of molten iron in the Earth's outer core.
Large igneous provinces (LIPs)
represent special events in the Earth's history that may have been caused by superplume activity.
Which of the following sedimentary structures indicates that the sediments were deposited in a moving fluid?
ripple marks
What is the most logical past environment to have produced a deposit consisting of very little sand and mud, but instead lots of broken-up carbonate shells of marine organisms?
shallow-water carbonate area
Silica-oxygen tetrahedron
silicon is the inside ball, oxygen is the outer big balls
Which of the following groups of elements make up most of the mass of the Earth's crust?
silicon, iron, oxygen and aluminum
Which of the following fits the definition of a mineral?
space nanodiamonds, because they a definable chemical composition
Order the steps in the formation of a disconformity.
start sediments were deposited in a marine environment sea level fell, exposing marine deposits subaerially erosion took place sea level sore, covering erosional surface, buried by marine sediments finish
Physicists have shown that the 92 naturally occurring elements in the universe form during the life cycle of stars. During what stellar process are the very large elements (those heavier than iron) created?
supernova explosion
Mountains
that are not volcanoes typically occur along plate boundaries.
Studies of interplanetary space have indicated that
the Earth's magnetic field is non-spherical.
A horizontal line on the Earth's surface has a plunge of
0 degrees If something is horizontal, it has 0° plunge; vertical plunge is 90°.
Identify the true statement.
Seafloor spreading causes continents to move apart; subduction brings them together.
Imagine you and your colleague are astronauts who have landed on the moon of a planet in another galaxy. One of your many tasks is to determine the circumference of the moon. You remember learning about how Eratosthenes calculated the circumference of the Earth using shadows and geometry, and you decide to use this technique on the alien moon.You set two poles upright on the surface of the moon that are spaced 1,000 km apart. One person stands at each pole and, at precisely noon, you each measure the angle of the shadow made by the pole. At one pole the shadow makes a 22.5 degree shadow, and at the other pole there is no shadow because the star of this system is directly overhead. What is the circumference of this alien moon?
16,000 km The circumference of the moon is 16,000 km, as shown by the following calculation: x=(360 x 1000 km) / 22.5
Plate tectonics theory was widely accepted by scientists in what decade?
1960s
Order the events chronologically that occurred in the formation of our Solar System.
1st an accretionary disk formed a protosun formed rings formed in the protoplanetary disk planetsimals collected to form photoplants last
A radioactive isotope of the element potassium decays to produce argon. If the ratio of argon to potassium is found to be 31:1, how many half-lives have occurred?
5 half-lives Starting with 32x atoms of K, after 1 half-life the ratio of Ar to K is 16:16, after 2, 24:8; after 3, 28:4; after 4, 30:2, after 5, 31:1. pg 470
identifies an angular unconformity where tilted sedimentary rocks are found beneath flat-lying sedimentary rocks?
B is an angular unconformity because the tilted rocks of the Grand Canyon Supergroup sit beneath the flat-lying Tapeats Sandstone. Note: C is not an angular unconformity, because in an angular unconformity the rocks below the erosional surface must be tilted, and the Muav Limestone is flat, as shown.
Based on your observations of the lava eruption at the West Mata volcano, which statement is most likely to be true of the igneous rock being formed?
Basaltic rock is being formed that has small mineral crystals due to the fast cooling that occurs in water.
Identify the true statement
Becquerel discovered principles of radioactivity, which led to the determination of the Earth's age.
Which of the following statements about hardness is true?
Calcite will scratch gypsum.
Which of the following lists fits the order of these three descriptions: Age of Mammals, Age of Dinosaurs, and longest geologic time period.
Cenozoic, Mesozoic, Precambrian
Identify the true statement.
Chemical sedimentary rocks are crystalline in texture.
Which of the following statements is true?
Conglomerates consist of multiple grain sizes.
Order the steps of volcanic island arc formation.
Convergence begins 1) A subduction trench forms where the subducting plate bends downward into the mantle. 2) An accretionary prism begins to form. 3) Magma, created by flux melting of the mantle, rises through the overriding plate. 4) Lava erupts onto the surface, forming volcanoes. a volcanic island arc forms
Select probable outcomes for rock that was once near the surface but is carried to depth in a mountain belt through continental collision.
Foliations develop. flow folds develop
Which statements are true about William Smith's discoveries?
Fossils are not randomly distributed throughout the rock record. Using fossils, the relative order in which different rock layers were deposited is discernable. Not all fossil species are present in all locations.
Identify the statement that is true about radiometric dating.
It can be used only if some radioactive element is present in the rock.
Why was Ceres re-classified as a dwarf planet?
Its shape was discovered to be spherical rather than angular.
dentify statements true of Pangaea.
Pangaea was one of several supercontinents that have formed and broken up during Earth's history. Rates of seafloor spreading in the Atlantic Ocean are compatible with what is known about the breakup of Pangaea. The regional-scale folds visible in the Appalachian Mountains are remnants of Pangaea's formation.
Which statement is true about the formation of the Moon?
The Moon formed from debris created when Earth suffered a catastrophic protoplanet collision.
identify statements true of the lithosphere and asthenosphere.
The asthenosphere is relatively soft compared to the rigid lithosphere. The asthenosphere underlies the lithosphere.
Which of the following statements is true?
The atomic number equals the number of electrons in a neutral atom.
Obsidian is a volcanic glass that forms when lava cools very quickly and consists of a solid mass of glass through and through. Why is obsidian not classified as a mineral?
The atoms or molecules in obsidian do not have a crystalline structure.
Using the figure above, predict the future location of the red circle. Note that the red circle will move, but the letters will not.
The circle is located along a mid-ocean ridge. Future movement associated with continued spreading will shift the circle westward to location C. pg 95
Which of the following statements about this diagram is true?
The fault occurred before the basalt dike intruded the region. Since the granite pluton is not folded, it must have intruded after (not before) the rocks were folded. The contact between the granite pluton (an igneous rock) and Bed 3 (a sedimentary rock) would be a nonconformity, not a disconformity. The fault is cut by the basalt dike, so the dike must be younger than the fault. Thus, Bed 5 (a sandstone) must be older than the igneous sill that sits beneath it; you can tell because there are inclusions of Bed 5 within the sill, and according to the principle of inclusions, the inclusions must be older than the bed where they are included.
Which of the following statements is true?
The generally accepted age of the Earth is 4.56 billion years.
Which of the following happens at a normal fault?
The hanging wall moves down relative to the footwall. The crust experiences extension.
What would be the significance of finding a precipitated mineral on another planet?
The planet may have or have had liquid water on it.
Order the steps in the creation of mantle-plume related volcanism
a ,mantle plume a regionally restricted column of hot rock, rises inside the asthenosphere at the base of the lithosphere the rock in the mantle plume partially melts magma is intruded upward into the plate magma erupts to form a volcano
Which of the following structures makes a pattern of rock layers on the ground surface that looks like this: parallel stripes, showing bilateral symmetry across a midline (hinge), with rock getting younger as you move outward from the hinge.
anticline
The heavier elements on the Earth (those with atomic numbers greater than 5)
are formed by stellar nucleosynthesis during the life cycles of existing stars.
Diamonds
are found in carrot-shaped structures called kimberlites.
According to the mantle plume model, hot-spot plumes
are thought to originate at the core-mantle boundary.
Ceres is the largest celestial body between Mars and Jupiter. It has a diameter of about 590 miles and is made up of ice and rock. Prior to being classified as a dwarf planet, Ceres was previously considered a(n)
asteroid
A black, fine-grained tabular intrusion that cuts across two layers of horizontal sedimentary rock must logically be a
basaltic dike Granite would be light-colored; a dike would cut across existing layers.
As sediment is transported downstream, away from its point of origin, the particles become
better sorted
Doppler effect
can be applied to sound waves.
Stars
can explode cataclysmically when they die and contribute their matter to future star generations.
Which of the following is a general term used to describe all the physical, chemical, and biological processes that make a sedimentary rock from sediments?
diagenesis
Decide which type of plate boundary the following items would most likely be associated with
divergent- crustal thinning convergent- andesitic volcanism, crustal thickening transform- shear stress
Bowen's reaction series
enables a geologist to predict what minerals will be found as magma cools.
Choose the most likely product of partially melting a rock of intermediate composition.
felsic magma
The East African Rift
has volcanoes along it because asthenosphere is rising under the rift and supplying heat.
Crystals
have an orderly internal arrangement of atoms arranged in a lattice pattern.
Place the events in the order they occur between the mid-ocean ridge and deep-ocean trench.
mid-ocean ridge ocean crust created sediment accumulates on oceanic curst oceanic crust scraped off plate to from accretionary wedge oceanic crust recycled into mantle deep ocean trench
Identify the following substances as mineral, mineral simulant, or non-mineral.
mineral- gypsum, corundum, aragonite, graphite mineral simulant- hematine, cubic zirconia non-mineral- menthol, sugar, DNA, glass
A clastic sedimentary rock with clay and silt-sized grains that does not break in thin sheets is called
mudstone
The two most common gases of the Earth's atmosphere, and their percentages, are
nitrogen (N2), 78%; and oxygen (O2), 21%.
The Earth's magnetic field is generated in the
outer core
Choose the list that accurately shows rock composition increasing in silica and decreasing in iron and magnesium.
peridotite, basalt, granite
Magnetic anomalies are
places where the magnetic field strength is either greater or less than the expected strength.
According to current plate tectonics theory,
plates are composed of the crust and the uppermost part of the mantle.
Which of the following lines of evidence for continental drift/plate tectonics was found after Wegener published his theory?
the existence of mid-ocean ridges, where seafloor spreading starts
The Badlands of South Dakota are elevated, eroded plateaus and valleys composed of undeformed sedimentary strata. These are not mountains, because
there's no deformation of rocks or structures
Categorize processes related to transform boundaries. Sort the following processes those likely to be related to a transform boundary or those likely associated with other boundary types.
transform boundary- earthquakes other- divergence, convergence, subduction
Peridotite is
ultramafic.
which tectonic setting would you expect to find igneous activity?
volcanic arcs bordering ocean trenches
heliocentric model
was supported by Johannes Kepler's observation that planets follow an elliptical orbit.
Igneous rocks
were the 1st rocks to exist on the earth
Earthquakes are generated
when rock moves along faults.
