Part 3—There and Back Again

In Part 2, you examined the fossil record of Nothofagus in Antarctica. The trends in plant distribution that you uncovered helped you infer past climate by considering where similar plants grow today. In this part of the chapter, you will use the skills you developed in Part 2 to investigate the timing of the last major glacial episode of North America and its impact on plant life. To complete this task you will access data from NOAA's Pollen Database, create a spreadsheet like the one you used in Part 2 and import the data into GeoMapApp.

Step 1 – Open a Base Map and Select a Site with Pollen Data

  1. If you still have GeoMapApp open from the last activity close it and restart the program. This time you will open the Mercator projection shown at the left of the start screen. Select it and click Agree. Notice the difference in this projection and how it distorts high latitude areas. However, for this exercise you will be focusing on the mid-latitudes of North America, so the projection is appropriate.
  2. Select the Zoom tool (magnifying glass with a plus sign on it). Use the Zoom tool to click and drag a box that covers the region of North America between the Great Lakes and the Atlantic Ocean. Remember, you may need to wait a few seconds for the server to import the higher resolution data!
  3. Now that you have zoomed in, you may want to select the Pan tool (looks like a hand) to center the image so that you can see the Great Lakes to the west and the Atlantic Ocean to the east in one map view. When you have centered your image, select the arrow Pointer tool to ensure you do not further change the image.
  4. Once you are zoomed and centered on your location, select Datasets > World Data Center Paleo Climate Open Archives > Pollen from the dropdown menu at the top of your screen.

  5. The list that appears shows authors who have published pollen data to the database. Drag the list to the right of your screen and check the box labeled Show on Map.

  6. Each box outline that appears on the map represents the general area of a particular pollen study site. Like the core sites in Antarctica, these areas have been studied by identifying pollen abundance and distribution through time. Consider the following question:
    • Why do you think the number of studies sites is so much greater in this region than it is in Antarctica?
  7. Scroll down the alphabetical list and highlight the entry entitled: Spear, R.W. Lost Pond (LOSTPOND) Global Pollen Database. Notice that this study area is now highlighted in white on your map. You may need to drag the top window out of your way to see the highlighted area. Once the entry is highlighted click OK at the bottom of the search window. This will direct your web browser to open the Lost Pond dataset on the NOAA Paleoclimatology website. Alternately, you may go directly to the NOAA site by clicking this link. Lost Pond Data.
  8. Once on the NOAA site, use the third link in the list, to the right of the picture, to access the p15 dataset.


  9. Note the site's Latitude and Longitude (44.246944N and -77.251389W). You will use these coordinates to locate the sediment core on your map. Also note the age constraints are much different than those you used in Antarctica. The Carbon-14 age constraints of the sedimentary sequence range from 13,480 years before present to 20 years before the present—much more recent than the first cores that you examined in this chapter!

Step 2 – Build a Spreadsheet File of the Data for the Site

In your study of Antarctica, you used a very small set of data to look at vegetation patterns over 10's of millions of years. In this section, you will create your own spreadsheet to format a larger dataset representing a much shorter time span. For this investigation, you will investigate the conifer genus Tsuga canadensis.

Before you begin, write a brief description of Tsuga canadensis in your journal. Recall that in Part 2 you wrote about an angiosperm: Nothafagidites fusca and discussed how it differed from conifers. Here you will provide details about a particular conifer species: Tsuga canadensis. There is a close relative of the Nothofagidites that you studied earlier in this dataset: it is the Fagus, or Beech tree. If you like, you can also add the Fagus % abundances to your spreadsheet and the following instructions.
  1. Now that you have a little background information, you will create a new spreadsheet in Microsoft Excel, or other spreadsheet program. To accomplish this, first launch Excel and set up a new spreadsheet with the following column headers: Latitude, Longitude, Age, and Tsuga % abundance. Save this file to your desktop or documents folder as "Lost Pond Pollen" and minimize it.
  2. On the NOAA Paleoclimatology page for Lost Pond, that you opened in Step 1, double click the data link labeled: pollen/asciifiles/fossil/p15files/gpd/lostpond_p15.txt. This text file shows the abundance data for the 15 most common types of pollen recovered at the Lost Pond site.
  3. Enter the Latitude and Longitude values for the Lost Pond site in the first two columns of your new spreadsheet.
    Note: For GeoMapApp to correctly process the location you must use the digital values shown in parenthesis. As you can see north latitudes have positive values and west longitudes have negative values.
  4. Copy and paste the latitude and longitude values down to row 35 in your spreadsheet.
  5. Take a moment to more closely examine the p15 data display on the website. It is quite confusing at first glance.
    • Begin to break it down by considering the following questions:
    • Next, take a look at the columns below the words "Reliable age bounds." Notice they are numbered 1-17. To the right of these numbers is an abbreviation for a plant genus and further right the names of the plants are spelled out. You will be using % abundance for the plant Tsuga.
    • Scroll down a bit more and you will find the data themselves. The column to the extreme left reads 1, 25, 30, 50, 75, 100, etc. This represents the depth, in centimeters, of the samples. Just to the right of these numbers is the sample age in years before present.
    • Each depth / age has a record to the right for the most abundant species recovered. Since you are interested in the records for Tsuga you will need to count over to the 13th entry in the file. Note that it is the third entry in the second row for each depth.

      Check your understanding by answering the following questions about the data in the table.
      • What number between 1 and 15 is assigned to Tsuga?
      • What is the age of the sample recovered from 1 meter (100cm)?
      • What was the % abundance of Tsuga at the depth of 1 meter (100cm)?
  6. Now that you know where to locate the data, type the sample age into the third column of the spreadsheet, and the % abundances for Tsuga into the 4th column. If you are also collecting Fagus data, add this to data the fifth column.
  7. Repeat this step to collect the correct information for each depth.
  8. When you are done make sure to save your work in a place that you can locate it for the next step.
    9. If you are unable to access the data for your spreadsheet, you can download and use the following table to complete the exercise.
    Spear Lost Pond Pollen (Excel 23kB Apr24 13)
    .

Step 3 – Import Lost Pond Data into GeoMapApp

  1. Left-click and hold the mouse button to highlight (select) the entire Lost Pond Pollen Spreadsheet. Make sure to include the column headers as they will be used in GeoMapApp. Use Ctrl + C or other command to copy the entire spreadsheet to your clipboard then, minimize the spreadsheet.
  2. On your GeoMapApp screen select File > Import Table or Spreadsheet > From Clipboard....

  3. The spreadsheet of Lost Pond data should show up in the window automatically. If it does not show up, you will need to repeat the appropriate steps, above, and try again.
  4. Click OK. As you did in Part 2, verify that your latitude column is labeled latitude and your longitude column is labeled longitude. Click OK again.

  5. Notice your core location icon appears now on the map just inside the area location box for Lost Pond. Use your Zoom tool to examine the topography around the lost pond core location. (Note: you may want to close the Pollen database sites from Step 1 to clean up your images.)

Step 4 – Compare Tsuga Abundance to Glacial Retreat

In this section you will use the skills you learned earlier to create a line graph of the change in Tsuga abundance over time.

  1. Once you have loaded your spreadsheet file into GeoMapApp, use the Pointer tool to select the Graph button from the Tool Box at the right to the map window as you did in Part 2, Step 3.
    • Select average age as your x-axis
    • Tsuga as your y-axis.
    • Select the line graph function
  2. Copy the graph and paste it in your working file or a word-processing document. Make sure to give the graph an appropriate descriptive title and a caption explaining what the figure shows. You can also give a citation for the graph by reviewing the Lost Pond publication information on the NOAA Paleoclimatology Lost Pond Data website.
  3. Answer the following questions about the graph.
    • When did Tsuga pollen first appear in the fossil record at Lost Pond?
    • When did it peak?
    • Describe changes in Tsuga abundance over the last few centuries.

Step 5 – Compare GeoMappApp Data to Images from Pollen Viewer

  1. Create a new tab on your web browser and open the pollen viewer website: Pollen Viewer
  2. Click on the down arrow to the right of the box that appears above the map. From the drop down menu scroll down to select Tsuga.

  3. Once in PollenViewer, use the forward and back buttons located under the Play button to move forward and back though time. Locate and review the general area of Lost Pond on the map image displayed. Answer the following questions in your journal while viewing the Pollen Viewer images.
    • Did you observe a spike in Tsuga abundance similar to the one you observed in your graph?
    • Write a brief description of the relationship between the location of the North American Ice Sheet and the abundance of Tsuga pollen.
    • Compare the results of this investigation with the one you conducted in Part 2. What similarities and differences do you observe?
    • List several factors that influence the advance and retreat of glaciers.

Step 6 – Develop and Test a Hypothesis of Your Own

Use the knowledge and skills you have acquired in Part 3 to develop and test a hypothesis to answer the following question.
How would the distribution graph for Tsuga differ if the data came from a core 100 km northwest of Lost Pond? Explain your reasoning. Be sure to include data, figures, and citations to justify your response.