Examination 1 Natural Sciences II (ERTH 1040), Feb. 24, 2006 There - - PDF document

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Examination 1

Natural Sciences II (ERTH 1040), Feb. 24, 2006 There are 28 questions over 5 pages on this examination. You have 50 minutes to complete the exam. You may use a calculator, a ruler, and writing implements. Please read each question carefully. Also note that the questions towards the end are worth more, so budget your time accordingly. Part I – multiple choice and short answer questions (π points each)

• 1. Which best describes “Scientific Law”

a. It is a behavior of a natural system that can be directly tested through repeated observation

• b. It is a hypothesis that has held up to repeated scrutiny and supported by a wide-range of

evidence c. It is an initial impression of a natural system.

• d. It is a hunch or loosely-constrained idea
• 2. The surface of the moon contains craters accumulated over billions of years. This is because…

a. The moon cooled off three billion years ago

• b. Asteroids and comets have intersected the earth’s orbit in the past

c. There have been little to no tectonics on the moon for three billion years

• d. There has been little to no erosion on the moon for three billion years

e. All of the above

• 3. When the iron-oxide mineral, magnetite, is cooled from high temperature to below 560ºC, it’s

Curie point,… a. It pops out of its host rock

• b. It traps oxygen

c. It locks in a specific uranium-lead isotopic concentration

• d. It locks in the orientation of the earth’s magnetic field

e. All of the above

• 4. Which meteorite has a composition of the earth’s mantle (upper mantle+crust)?

a. Chondrite

• b. Achondrite

c. Iron-nickel meteorite

• d. Ice VII

e. Fulgerite Bonus (2 pts) How old are most meteorites? 4.6 billion years

• 5. This week, researchers from Johns-Hopkins,

SRI, STSI, and Lowell Observatory reported that they found two new moons orbiting Pluto using the Hubble telescope. Yet, three weeks ago in this class we learned that Pluto has only

• ne moon. Which is correct.

a. Obviously the researchers are wrong

• b. The new moons popped into existence last

year c. New observations produced new data, changing our understanding

• d. Despite the pricey tuition, RPI can only

afford to tell its students about one moon.

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• 6. Local noon (the sun at its highest point in the sky)…

a. Occurs sharply at 12:00 EST in Troy, each day

• b. Occurs one hour later for every 15º west longitude

c. Happens all night at the north pole in winter

• d. Is the test start time

e. Occurs immediately after martini time.

• 7. What happened in the colony of New York on September 10, 1752?

a. George Washington surrendered Fort Necessity to the French

• b. The British, under Amherst, took Fort Ticonderoga

c. William Henry Harrison’s clock permitted accurate assessment of longitude

• d. The earth’s true diameter was measured by French naturalist, Jean-Claude Kildaire

e. Nothing – note that this date was removed in Britain’s shift from Julian to Gregorian

• 8. Which is the actual length of time in days between northern-hemisphere spring equinoxes?

a. 365 days

• b. 365.2524 days Gregorian

c. 365.2424 days

• d. 365.25 days Julian

e. 7 dog days Bonus (1pt each) – label the corresponding answers above for the length of an average Julian year and the length of an average Gregorian year (averaged over 2000 years).

• 9. The Coriolis force on earth greatly influences…

a. Wind patterns

• b. Airplane routing

c. A toilet flush

• d. Both a & b

e. Both b & c

• 10. Earth history can scaled to relative (as opposed to absolute) time based on

a. Radiochronology (measuring the concentrations of unstable elements and their stable products)

• b. The appearance and disappearance of specific fossil life forms

c. Tree ring dating

• d. Ichthodendrology

e. The time-traveling adventures of Mr. Peabody and his boy Sherman

• 11. We know the structure of the Earth (the depth of interior boundaries) from…

a. Meteorites

• b. Direct sampling

c. The transmission of earthquake waves

• d. The exploits of the terranauts, in the based-on-a-true-story movie, The Core
• 12. Which of the following is not among the most common elements in the entire (bulk) Earth?

a. Silicon

• b. Iron

c. Carbon

• d. Magnesium

e. Oxygen

• 13. What controls the magnitude of an earthquake?

a. The type of fault

• b. The length of the break in the earth

c. The time between P and S waves

• d. The generation of a tsunami

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• 14. Which is not true of the island of Hawai’i (the Big Island)?

a. It is made of mid-plate hot spot volcanoes

• b. It contains the youngest rocks of all the Hawaiian islands

c. It is south of the Tropic of Cancer

• d. It is near a plate boundary

e. It has snow-covered, shield-shaped mountains

• 15. The oldest sea floor is …

a. Between 10 and 30 million years old

• b. Between 30 and 50 million years old

c. Between 120 and 220 million years old

• d. Between 1.0 and 2.5 billion years old

e. In the oldest mermaid’s house

• 16. Which is not true of the moon

a. It causes the earth to zig-zag in its orbit around the sun

• b. It is composed of reflective anorthosite rock and darker basalt

c. Its mass causes tidal response on the earth

• d. Its phases directly determine the length of the Gregorian calendar

e. It was formed after the earth’s iron catastrophe. Bonus (2 points): Is there a dark side of the moon? Why or why not? Not in a permanent sense – it rotates such that one side always faces the earth so light moves across it.

• 17. What causes volcanism at subduction margins (ocean-ocean, or ocean-continent collision)

a. thinning of the lithosphere (depressurization)

• b. dewatering of the subducted oceanic lithosphere

c. melting of the subducted oceanic lithosphere

• d. heat plumes rising through the mantle from the core

e. magma men

• 18. The diagram on the right schematically shows initially flat lying rocks that have undergone

a. Brittle extensional deformation

• b. Brittle compressional deformation

c. Ductile extensional deformation

• d. Ductile compressional deformation

e. a and c f. b and d Bonus (2 points): Draw arrows on the diagram to the right to show the direction of principle deviatoric stress. Horizontal and points outward

• 19. Which is not an influence on volcanism

a. Amount of dissolved volatile components in the magma (such as H2O and CO2)

• b. Magma supply rate

c. Earthquake frequency

• d. Magma viscosity

e. Magma composition

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• 20. The Himalayan mountains are the result of

a. Subduction of the Pacific plate under the Eurasian plate

• b. Transform faulting in southern Asia

c. Subduction of the Eurasian plate under the Pacific plate

• d. The collision of the Indian continent with the Eurasian continent

e. They were raised as part of the “free Tibet” movement

• 21. Rifts, either continental or oceanic, are marked by…

a. Compressional faulting

• b. Folding

c. Extensional faulting

• d. A lack of deformation

e. Large herbivore super lizards

• 22. Most of the earth’s available freshwater is…

a. Trapped in polar ice

• b. Underground

c. In lakes, streams, and oceans

• d. In the mantle

e. Is conveniently packaged in 8 ounce bottles

• 23. When water evaporates

a. It releases heat

• b. It absorbs heat

c. It condenses

• d. More molecules return to the liquid than leave for the air

e. It keeps on going downhill

• 24. Most aquifers are hosted in rocks or sediments with…

a. High porosity and low permeability

• b. High porosity and high permeability

c. Low porosity

• d. High clay content

e. With numerous wells

• 25. (4 pts) To date, no one has sent a spacecraft to Mars that has returned to Earth. Yet we have

several samples of Martian crust. How is this? Achondrite meteorites

• 26. (3 pts) How do we know the outer earth’s outer core to be partially molten? No shear (no s wave

propagation) Part II: Longer answer

• 27. (8 points) On the solstice, the vertical flagpoles outside the RPI union are located at 43.71° N

73.67° W. Note – this problem is a rehashing of that solved by Eratosthenes using shadows in Egypt. What is the angle of the shadow cast by the flagpoles on the summer solstice? 20.2º N If there is an identical set of flagpoles on Long Island, The Bahamas (23.5º N 75.18º W), what shadow do they cast on the summer solstice? No shadow (0º) – at Tropic of Cancer

Name:____ _______________ Page 5 The two places (RPI and Long Island, The Bahamas) are roughly 2,100 km apart. Assuming the earth to be a sphere, calculate a diameter for the earth (recall that the circumference of a circle, including the great circle of a sphere, is C = π d). For this calculation, you may ignore the slight change in longitude between the two locations. Show all work for possible partial credit. (12 points – for a thoughtful answer that provides sound evidence for its thesis) Do you think that the continents have been slowly created over time or have they been about the same size since the Earth differentiated (~4.5 billion years ago)? Provide a thoughtful answer explaining where crust is created (and whether such crust is continental or oceanic) and where crust is consumed as understood in the Plate Tectonic theory. Explain any constraints on your understanding. Consider drawing a diagram to aid your explanation. C = 2100 km x [ 360º / 21.2º ] C= 37,462 km d = C / π = 37,462 km / 1.14159… d = 11,913 km