FAQ about the mid-term

1. FAQ about the mid-term • When: Thursday, February 19, 2015 during normal class period • Where: • If your last name starts with A to L : Leacock-219 (this room) If your last name starts with M to Z: Otto Maass, Room 10 • Short questions; short answers. • No multiple choice questions. • Book chapters covered: Chapters 1 to 5

2. UNDERSTANDING PLANET EARTHEPSC-201MID-TERM TEST QUESTIONS DATE:   NAME: STUDENT #: INSTRUCTIONS:Answer ten (10) of the fifteen (15) questions in the spaces provided. If you chose to answer more than 10 questions, only the first 10 answers will be marked. Provide sketches where appropriate. All questions are weighted equally. No documentation permitted. Only basic calculators are allowed.

3. Question 1: What two pieces of evidence are typically presented in support of the Big Bang theory?

4. The expanding Universe Hydrogen light observed from distant galaxies, shifted to longer wavelengths or towards the red of the light spectrum– “Red Shift”. Hence, the hydrogen light spectrum from distant galaxies is recorded on Earth at different wavelengths which are characteristic of the retreat velocity of the galaxy.

5. Background radiation from the Big Bang Arno Penzias Robert Wilson 1963 The shape and intensity of the radiation spectrum is characteristic of a given temperature

6. Question 1: What two pieces of evidence are typically presented in support of the Big Bang theory? • Hydrogen light observed from distant galaxies is shifted to longer wavelengths or towards the red of the light spectrum– “Red Shift”. In other words, all galaxies are moving away from the Earth. “Red Shift” measurements indicate that the more distant a galaxy, the faster it is moving away from the Earth. Hence, the Universe is expanding. • The presence of long-wavelength electromagnetic radiation in the dark voids between stars and galaxies. This afterglow is believed to be the thermal signature of a very hot cloud of gas whose temperature dissipated by expansion of the Universe

7. Question 2: • What is an ion? • What is a positive ion called? • Why are positive ions typically smaller than negative ions having a similar number of electrons in their electronic cloud?

8. CATION positively-charged ion ANION negatively-charged ion For atoms with similar numbers of electrons, cations will typically be smaller than anions.

9. Question 2: • What is an ion? • An element that has shed or captured an electron from its electronic cloud and for which the number of electrons in the electronic cloud is no longer equal to the number of protons in its nucleus. Consequently, this element carries a net positive or negative charge. • b) What is a positive ion called? • A cation. • c) Why are positive ions typically smaller than negative ions having a similar number of electron in their electronic cloud? • Because they have lost one or more electrons from their electronic cloud, they hold on more tightly to the ones that remain.

10. Question 3: Briefly outline a theory for the birth and death of stars. Where do gravity, red giants and supernovae fit into this theory?

11. Question 3: Briefly outline a theory for the birth and death of stars. Where do gravity, red giants and supernovae fit into this theory? The expanding cloud of gas from the Big Bang (and subsequent nucleosynthetic events) broke up into clusters. Once a gas cloud collapses into a star, kinetic and gravitational energy are converted to heat which ultimately initiates thermonuclear reactions. In the largest stars (Red Giants), a cycle of fuel depletion, renewed collapse, core temperature rise, and ignition of a less flammable nuclear fuel is repeated several times until the star implodes into a supernovae.

12. Question 4: What are the four possible states of matter?

13. States of matter solid plasma liquid gas

14. Question 4: What are the four possible states of matter? Solid, liquid, gas and plasma.

15. Question 5: • What is the highest mountain on the surface of the Earth (the one that stands highest above sea level)? • Where and at what depth is the deepest oceanic floor?

16. Question 5: • What is the highest mountain on the surface of the Earth (the one that stands highest above sea level)? • Mount Everest in the Himalayan mountain belt. • b) Where and at what depth is the deepest oceanic floor? • The Mariana Trench, east of the Island of Guam in the Northwest Pacific,at nearly 11,000 m depth.

17. Question 6: What three lines of evidence support Wegener’s hypothesis of continental drift?

18. Evidence from ancient climates: past glaciations and equatorial climate belt

19. Continental drift and the fossil record

20. Evidence from geological structures and rock types

21. Evidence from paleomagnetic measurements: polar wandering curves

22. Question 6: What three lines of evidence support Wegener’s hypothesis of continental drift? • Evidence from ancient climates: past glaciations and the equatorial climate belt • Presence of glacial tills of the Carboniferous period in South America, South Africa, India, Australia, areas now located in subtropical to tropical regions where glaciers are unlikely to be found. Distribution of major coal fields that date from the same period and are found today in continents of the North Hemisphere. • Paleontological evidence • Striking similarities of certain fossils found on continents now separated by large oceans. • Evidence from coincident geological structures and rock types on continents now separated by an ocean. • The continuity of geological formations and correspondence of ages of rocks found on the east coast of South America and the west coast of Africa. • Evidence from paleomagnetic measurements: polar wandering curves. • The polar wandering curve based on European paleomagnetic data is roughly parallel to the North American curve but separated by about 30o in longitude for much of the Paleozoic and Triassic time (210 to 600 M.Y.B.P.).

23. Question 7: Explain what is meant by the term “polar wandering”.

24. Apparent polar wandering curve

25. Question 7: Explain what is meant by the term “polar wandering”. Apparent movement of the position of the Earth’s magnetic pole with respect to the pole of rotation, as determined from the magnetic record imprinted in rock of various ages. When igneous rocks (e.g., lava flows) form, they become weakly magnetized as they cool below the Curie point (~500°C), and the direction of magnetization preserves a "fossil" record of the Earth's magnetic field at the time and place of formation. Assuming that the rocks have not been rotated, folded or otherwise magnetically disturbed (e.g., heating), the rocks provide the magnetic declination or direction of the magnetic pole at the time the rock formed and the magnetic inclination from which the magnetic latitude can be calculated. Once the magnetic latitude of a rock and the direction of the magnetic poles are known, the position of the magnetic pole at the time of formation can be determined.Geophysicists have reconstructed paleomagnetic pole positions for the last 600+ million years and showed that the pole has wandered all over the globe. The plots of paleo-pole positions are referred to as paths of apparent polar wandering.

26. Question 8: How is it possible to determine rates of seafloor spreading? Name three methods.

27. ISOCHRONS are contours of equivalent age of the seafloor. They show the time that has elapsed and the amount of spreading that has occurred since the magnetized rocks were injected as lava into a mid-ocean rift.

28. Laser-ranging across divergent margins GPS measurements across ocean basins

29. Question 8: How is it possible to determine rates of seafloor spreading? Name three methods. • Magnetic stratigraphy of polar reversals established on land can be applied to the sequence of magnetic anomalies recorded in the seafloor to determine the rate of seafloor spreading. The spacing of strips differs in the various oceans because the sequence of reversals is either compressed or stretched out according to slower or faster spreading. • Laser ranging across divergent margins (e.g., Red Sea, East African Rift) • Global Positioning System (GPS) measurements across ocean basins (e.g., Atlantic)

30. Question 9: The Hawaiian Islands represent a chain of volcanic islands. How did they form?

31. Question 9: The Hawaiian Islands represent a chain of volcanic islands. How did they form? The Hawaiian Islands sit above a long-lived magma source that lies deep in the mantle, a hot spot. As magma oozes up from the mantle, it creates a volcano on the surface of the drifting lithosphere. As the lithosphere moves over the hot spot, it leaves behind a trail of volcanoes increasing in age from one to the other.

32. Question 10: a) Is the “white” refined sugar you use to sweeten your morning coffee a mineral? b) Explain your answer with respect to the mineralogical criteria.

33. Question 10: a) Is the “white” refined sugar you use to sweeten your morning coffee a mineral? Answer: No b) Explain your answer with respect to the mineralogical criteria. • Homogeneous - Yes • Naturally occurring – No (refined & recrystallized from an extract and, thus, man-made) • Solid - Yes • Definable chemical composition - Yes • Orderly arrangement of atoms - Yes

34. Question 11: Few metals are found in their “native” state in nature (metal atoms with no charge, i.e., #é = #protons). Name three “native” metals found in natural deposits.

35. Question 11: Few metals are found in their “native” state in nature (metal atoms with no charge, i.e., #é = #protons). Name three “native” metals found in natural deposits. Answer: Iron, copper, gold, silver, mercury.

36. Question 12: Describe the molecular structure of pyroxene (a silicate mineral).

37. Question 12: Describe the molecular structure of pyroxene. Pyroxenes are single chain silicate minerals. In a single chain silicate, the silica tetrahedra are linked to form a chain by sharing two oxygen atoms. [Pyroxenes are a group of black or dark-green minerals that occur in elongate crystals with two cleavage directions at 90° to each other.]

38. Question 13: • What are pyroclastic flows? • Give two reasons why they are so devastating?

39. Pyroclastic flows or « nuée ardente » Mt. Unzen, Japan Hot (220-450°C) clouds of pyroclastic debris that travel at great speed (up to 300 km/hr).

40. Question 13: • What are pyroclastic flows? • Fast moving avalanches of hot pyroclasticdebris (hot ash and lapilli) that rush down the flanks of a volcano. • b) Give two reasons why they are so devastating? • They are very hot clouds of debris (220-450oC) that travel at great speed, up to 300 km/hr.

41. Question 14: Explain why melting of mantle occurs at subduction zones.

42. Question 14: Explain why melting of mantle occurs at subduction zones. At subduction zones, hydrated minerals contained within the subducting oceanic lithosphere and sediments introduce volatiles to the mantle and induce melting between the subducting slab and the overlying lithospheric plate. The presence of volatiles helps to break up the chemical bonds that hold mineral grains together and, consequently, decrease the melting point of rock.

43. Question 15: When a rock undergoes mechanical weathering it is broken into smaller and smaller pieces, each retaining the characteristics (i.e., mineralogy, composition) of the original or parent material. How does this affect chemical weathering rates?

44. Question 15: When a rock undergoes mechanical weathering it is broken into smaller and smaller pieces, each retaining the characteristics (i.e., mineralogy, composition) of the original or parent material. How does this affect chemical weathering rates? By breaking rocks into smaller pieces, mechanical weathering increases the amount of surface area available for chemical weathering.In other words, more of the rock is exposed to the atmosphere (air, moisture) and becomes available for surface reactions.