Earth Science 1

Oceanography Discussion

Sample Problems

The word problems below are typical of the problems you will be required to do in the lab for this course. Answers to these questions will be posted in the middle of the quarter. If you have any questions about how to do these problems, please ask your TA. If most of the math involved in these problems looks unfamiliar, please contact your TA or a math tutor.


1. Assume 24% of all Texans live within 70 miles of Houston

a. Assuming the state population is 425 thousand people, how many Texans live within 70 miles of Houston?

b. Express the value 425 thousand in standard notation (with zeroes instead of words) and in scientific notation.

c. Convert 70 miles to kilometers

d. Convert 70 miles to centimeters

e. Convert 70 miles to feet

2. If a frozen lake has a surface area of 25 thousand square feet and there are 80 people skating on the lake:

a. What is the surface area in square meters?

b. What is the population density on the lake?


3. There is an imaginary city in the US called Jimville. 45% of the inhabitants are African-American. 23% are Latino, 30% are Eurasian, and 2% are Native American. If the number of African-Americans living in this city is 2.4 million people, how many Eurasians, Latinos, and Native Americans live in Jimville?


4. If Brenda takes a trip from Sao Paulo, Brazil to Santa Cruz, California.

a. Find a world map, and give the distance between these two locations in kilometers and in miles.

b. If the trip lasted 10 days, what speed was Brenda traveling at (In miles per hour)?


5. What is the scale of the map you are using?


6. On a map of Beitler Bay, the Dahl Submarine Canyon extends offshore from Jimville a measured length of 40 cm. The map scale is 1 cm = 5 km, calculate the offshore extent of the canyon. Give answer in km and miles.

7. The distance to the shelf break due south of Jimville is known to be 15 km. If the map scale is 1 inch = 1 mile. What is the expected measurement from Jimville to this feature in cm?

8. The Andreasen spreading ridge is located in the Fischer Ocean. Based on paleomagnetism, the age of the seafloor 500 km from the Andreasen spreading ridge is 20 My. Calculate the seafloor spreading rate in cm/yr.

9. Based on the calculated spreading rate for the Andreasen ridge, calculate the time necessary for the Fischer Ocean to open to a width of 3000 km and 6000 km.


10. A fault has displaced rocks of the same age by 200 km. These quakes occurred at a rate of 1 earthquake every 5 years. Every earthquake displaced the rocks by 1 m. How old are the rocks?
 


Ocean Chemistry

necessary information: Ocean volume: 1.38 x 109 km Ocean Mass: 1.41 x 1021 kg Density of river water: 1 gm/cm3


10) A water mass in the ocean has a density of:

a. 1.024 g/cm3. Express this in kg/m3.

b. 1025 kg/m3. Express this in g/km3.

c. What could account for the difference in the densities of these two water masses?

d. If these two mater masses were to mix which would form the bottom- most water mass?

11a) Approximately 2.8 x 1018 kg of water enters the ocean every year as river runoff. Assuming that most of this water this leaves the ocean through evaporation, what is the residence time of water in the ocean?


11b) If the average concentration of calcium (Ca) is 12 mg/kg of seawater, calculate the total mass of Ca in the oceans. Report the answer in kg.

11c) If the average concentration of Ca in river water is 0.4 mg/kg, and rivers are the only source of Ca to the oceans, calculate the residence time of Ca in the ocean.


Ocean Physics:

necessary information: Ocean volume: 1.38 x 109 km3 Latent heat of evaporation and condensation: 540 cal/g @100°C.


12) If 4.7 x 105 km3 of water evaporates from the surface of a lake every year through evaporation:


a) What mass of water evaporates every year? Assume the density of the water is 1.0 g/cm3. Report the answer in grams and kilograms.


b) What is the latent heat required to evaporate this mass of water each year? Report the answer in kilocalories.



Paleoceanography

13) What is the average accumulation rate for:

a) carbonate sediment that is 800 meters thick and accumulates over 5 million years?


b) carbonate sediment that is 40 meters thick and accumulates over 7 million years.