Question | Answer |
Why do most metamorphic rocks have a fabric (planar and/or linear alignment of mineral grains) | Because most have been dynamically recrystallized |
Durring strike-slip faulting: | Crustal blocks scrape past one another, which frequently leads to massive earthquakes |
Which of these was NOT part of the evidence supporting sea-floor spreading? | The homogeneous basaltic composition of sea floor lavas |
When stressed slowly, silly putty: | Gets thinner and thinner, like deep crustal rocks at a divergent plate boundary |
It is famously difficult to determine the age of deposition of clastic sedimentary rocks using absolute geochronology techniques. The best approach to this problem would be: | Attempt to date the mineral cement that holds grains together |
Reverse faults and folds are related in this way: | The both result from compression |
Which is most accurate about seismic waves | P-waves travel more rapidly through dense material than through llow-density material |
Which is most accutate about metamorphism? | Mafic (basalt); the crust is thinned, and the mantle melts as pressure decreases |
Which of the following is most accurate about the significance of metamorphic rocks? | The record evidence of how the crust thickens, thins, and is deformed over time |
Which of these is most llikely to blame for the destructive 1811-1812 New Madrid earthquakes (in the interior of the North American continent) | Sudden release of stress on ancient faults, where the crust is weak |
Which is most accurate about earthquakes? | The happen where stress builds and released suddenly |
What is most accurate about atoms of radioactivity carbon-14 | They form when cosmic rays collide with atoms of atmospheric nitrogen-14 |
An earthquake occurs in Mexico City, Mexico. The following is most accurate: | P-waves from the quake arrive at our seismograph in Oswego before S-waves |
A perfectly preserved bone fragment has been buried for exactly two carbon-14 half-lives. How long has the fragment been in the ground? (Carbon-14 half life = 5380yr) | 10,760 years ( Times halflife by 2. (“exactly two carbon-14 half-lives”)) |
Why does thickening the crust generate orogenic belts containing huge bodies of granite (batholiths)? | When the crust thickens, high grade metamorphic reactions release water, melting the crust. |
Which of these is the most diagnostic for estimating the Mercalli intensity of an earthquake in an area: | the identification of ground rupture and broken underground utility pipes |
Which would be the case if the Earth did NOT have a solid inner core: | (a) There would be no S-wave shadow zone.
(b) The S-wave shadow zone would be much smaller than it is today.
(c) P-waves and S-waves would travel through the Earth in the same amount of time.
(d) none of these (The answer is none of these) |
The age of the formation of the Earth is (within ±5%): | 4.5 Byr (billion years). |
Earthquakes are concentrated at plate boundaries, but some occur in the interiors of plates, far from boundaries. What does this tell us about stress in the crust as a whole? | Stress occurs throughout the entire crust, stress released more often at weak points |
Why does oceanic crust contain rocks exclusively less than 200 Myr old, whereas every continent contains rocks in excess of 2000 Myr old? | - Oceanic crust denser than continental crust melted down into mantel |
Give THREE pieces of evidence that Wegener used to support his theory of continental drift. | Fossils, Glaciers, Rock ages, |
Reverse Fault | Acute angle went up, obtuse went down |
Sheer Stress | Compressional Boundary |