Lesson 10: East African Rifting

Assignment: Palynology from African Rift Lakes

In this activity you will use data obtained on fossil pollen from sediment cores in five different lakes from the African Rift Valley in order to chart the climatic history of the region. You will be given data from six cores, and you must use those data to interpret the changing amount of rainfall throughout the region over the nearly 13,000 years for which you have data.

Use the data supplied in the "Palynology from African Rift Lakes" Resource Page (located in our Lesson 10 folder of ANGEL) to answer the questions below and to assess the paleoclimatic changes that have occurred in the East African Rift Valley.

You will find a form in the Lesson 10 folder of ANGEL called "Palynology from African Rift Lakes" Submission Form. This is where you will submit your responses to the questions listed below.

Suggestions for tackling this assignment: How to read palynology charts

The graphs in the"Palynology from African Rift Lakes" Resource Page(located in our Lesson 10 folder of ANGEL) were drawn on the basis of data from the African Pollen Database. (It is suggested you take a quick look at the graphs now, so you can tie in the rest of the material presented here to the data.) They record the relative abundances of several selected species of trees, shrubs, grasses, and wetland plants as reflected by the presence of pollen from these plants within sediment cores taken from the lakes indicated. To gather these data, sediment is taken from the lake bed in a long tube (you can see the depth of the core in centimeters along the red line at the left hand side of each panel). The sediment is washed, dried, and sieved, and the tiny grains of pollen are separated from all other soil constituents and examined under a microscope. Tedious work, indeed!

Specific organic-rich horizons are dated using 14C techniques, and those ages are reported with their uncertainties along the left side of each panel. The red dots indicate the depths at which the dates were obtained. You will need to interpolate within and between graphs to constrain the timing of environmental changes. Notice that each panel covers a specific range of time and, for the most part, they do not overlap with one another.

In these panels, blue labels and yellow patterns indicate tree species, while brown labels and patterns indicate herbs, ferns, and grasses. The x-axis scales of absolute percentage of each species’ pollen have been removed so that you can focus simply on the presence or absence of each species. Individual species presented in these panels were chosen following two criteria:

  1. they must be species identified in a majority of the cores used, and
  2. they must provide some indication of the degree of moisture available in the environment.

Use the table on the bottom of the Resource Page: Palynology from African Rift Lakes to decide which species will be most useful to you in determining the changing rainfall patterns over the East African Rift Valley.

Be aware that you may encounter data that are contradictory—welcome to my world of science! You should make an informed decision as to how you will interpret that data and clearly discuss your interpretation.

As always, Turnitin.com is available for you to use as a resource to verify your responses are in your own words.

Keep in mind... I am going to assume that everyone knows nothing about palynology and the paleoclimatic history of East African Rift Lakes! So your job in this course is to prove to me that you are learning something! I will look for details and evidence that you have thought about the material. And trust me, I can see through "fluff" that is copied directly from the Internet!

Deadline

All responses must be uploaded in the ANGEL no later than 11:00 PM on the due date (see Calendar tab in ANGEL). Note that is 11:00 PM by ANGEL's clock, not by the clock on your computer! The submission form will disappear at 11:00 PM, and this assignment will not be accepted late under any circumstances. I have no problems giving students a zero for an assignment if they do not take the responsibility to submit by the deadline, so don't even think about trying to submit this late!

Assignment Questions:

  1. Summarize (in your own words) a synthesis of the pollen data for Wenchi, Ethiopia. Include an explanation of increases and decreases in rainfall over time, written from the oldest event to the youngest event.
  2. Summarize (in your own words) a synthesis of the pollen data for Oyo, Sudan. Include an explanation of increases and decreases in rainfall over time, written from the oldest event to the youngest event.
  3. Summarize (in your own words) a synthesis of the pollen data for Bir Atrun, Sudan. Include an explanation of increases and decreases in rainfall over time, written from the oldest event to the youngest event.
  4. Summarize (in your own words) a synthesis of the pollen data for Lake Turkana, Kenya. Include an explanation of increases and decreases in rainfall over time, written from the oldest event to the youngest event.
  5. Summarize (in your own words) a synthesis of the pollen data for Lake Tanganyika (North), Democratic Republic of the Congo (Zaire). Include an explanation of increases and decreases in rainfall over time, written from the oldest event to the youngest event.
  6. Summarize (in your own words) a synthesis of the pollen data for Lake Tanganyika (South), Zambia. Include an explanation of increases and decreases in rainfall over time, written from the oldest event to the youngest event.
  7. Now that you have learned about the climate record from each individual core, describe the climatic history of the region. Discuss the changing amount of rainfall throughout the region over the at least the 13,000 years for which you have data.
  8. References in APA format (if you used any from outside ANGEL).

Resources to help get you started

All information you need for this assignment is included in this page and in the resource page. Pay careful attention to the graphs and pollen species identified downcore.

Grading criteria

Here is how the assignment will be graded.

  • Question #1-6 will be graded on a scale of 0-3, with 3 being the highest value possible. Zero points will be awarded if the answer is completely incorrect or left blank.
  • Question #7 will be graded on a scale of 0-10, with 10 being the highest value possible. Zero points will be awarded if the answer is completely incorrect or left blank.
  • As for your references, I am looking for correct format in APA style. If you do not have the correct style, then I reserve the right to deduct 15 points off of your final assignment grade (once it is scaled to 100%) for inaccurate documentation. If there is an academic integrity violation, I will puruse the procedures outlined in Lesson 0. If you do not use any references for this assignment besides the data table provided, please write "no additional sources used" in the space provided. You do not need to reference the data I provide with this assignment.

The entire assignment is worth 28 points and will be scaled to a percentage out of 100%.

How do you find out your assignment grade?

One week after the assignment is due, the submission form will become "active" again. You need to go back into the form and click on your responses to see your score and my comments. Again, I will be recording in my gradebook your score based out of 100%.

If you have any questions...

...on this assignment, on Africa, on anything! Don't hesitate to get in touch with me via phone or email ASAP. I would not recommend waiting until the last minute to contact me, as I cannot guarantee a response before the assignment deadline.