midterm 1 winter 2009
ATOC/EPSC/GEOG 104 The Earth System Midterm #2 March 26, 2009
The exam period is from 13:05 to 14:25. Answer every question in the space provided. The back of pages will not be graded; you may use them as scratch paper. Closed book. IMPORTANT: Write your name and student number at the top of every page. Exams will be split apart for grading and your work could get lost if you forget to do this!
ATOC/EPSC/GEOG 104 Midterm 2 Name__________________________________
March 26, 2009 Student Number________________________________
The (mostly) Solid Earth 1) You’ve inherited some beautiful land on the slopes of a volcano: a) It hasn’t erupted in recent memory, but you’ve read a scientific study that analyzed a tree log underneath a lava flow. This log contains half of the amount of carbon-14 found in modern trees. Is this volcano dormant (between eruptions) or extinct (will never erupt again), and why (think about the timescale of plate tectonics)? (5pts)
b) Why would anyone live on the slopes of a volcano (a practical reason)? (2 pts)
c) what sorts of eruptive processes might harm you or your property? Does it matter what kind of volcano this is? If so, why? (think of the plate tectonic environment) (5 pts)
2) a) Strong rocks produce larger earthquakes in areas of active deformation (active plate boundaries). Why would this be? Use the word ‘elastic’ in your answer. (3 pts)
b) What is a tsunami and how is it generated? (4 pts)
3) a) Almost all of the geological time periods were defined before numerical ages were known for them; that is, before radioactive dating was developed. How could this be? (5 pts)
b) If you were walking next to a rock outcrop and found a fossil clam, you would know that these rocks were younger than what age (approximately)? (4 pts)
ATOC/EPSC/GEOG 104 Midterm 2 Name__________________________________
March 26, 2009 Student Number________________________________
4) Below is a geological cross section: a) What is the relative age of formation ‘B’ (a basaltic magma intrusion) compared to the other four formations (‘A’, ‘C’, ‘D’, and ‘E’) (careful!)? (3 pts)
b) what is represented by the wavy lines on this cross section? (3 pts)
5) Describe a way in which the atmosphere of the Earth differs from a geologically and biologically dead terrestrial planet. How did it get this way? Mention at least two different gasses. (6 pts)
6) a) During the Snowball Earth, something called ‘ice-albedo feedback’ contributed to freezing the oceans all the way to the equator. What does this mean? (5 pts)
b) Once frozen, how could the Snowball Earth unfreeze? (5 pts)
ATOC/EPSC/GEOG 104 Midterm 2 Name__________________________________
March 26, 2009 Student Number________________________________
Atmosphere, Oceans and Climate 7) a. What are the three types of natural climate forcing? (3 points)
b. Of these three, which is considered most responsible for the ice ages? (3 points)
c. We know from ice cores that during ice ages atmospheric carbon dioxide concentrations have fallen as well as temperature. Describe the feedback process responsible for the dwindling concentrations and into what reservoir does the carbon dioxide go? (6 points)
d. How could one estimate past global temperatures from air bubbles trapped in ice sheets? (5 points)
e. Besides ice cores, name a type of proxy data one could use to study the climate of the last ice age. (5 points)
ATOC/EPSC/GEOG 104 Midterm 2 Name__________________________________
March 26, 2009 Student Number________________________________
8) a. Besides warmer air temperatures, list three consequences global warming might have on the Earth system. (6 points)
b. What is the most abundant greenhouse gas in the atmosphere? (2 points)
c. Increased cloudiness in a warmer world could act both as a positive and a negative feedback on temperature. How? (6 points)
d. Explain how a warmer climate could increase the likelihood for both droughts and floods. (6 points)
9) a. Methane (CH4) is another important greenhouse gas in the atmosphere. What is its largest natural source? (3 points)
b. In class we discussed a theory by the climate scientist William Ruddiman that humans had been altering the composition of the atmosphere and the climate for over 8,000 years. By what mechanism could early societies do this? (5 points)
