Getting to the Core: Understanding Lakes through Sediment Coring

Pre-/Post-AssessmentTeacher Note: This assessment may be used prior to and following instruction to evaluate learning objectives.

Questions 1 and 2 address learning objectives from Activity 1; Question 3 addresses Activity 2 objectives; Question 4 addresses Activity 3 objectives; Questions 5 and 6 relate to objectives from Activities 4 and 5.

DirectionsQuestion 1-2. Circle the letter of the answer that best answers each question.

Question 1. How are glacial lakes formed?

A. They form when two glaciers crash into each otherB. As glaciers move, they grind away soil and rock to form lakesC. They are formed on the top layer of glaciers when ice melts

Question 2. Where do rift lakes generally form?

A. Along the boundary of tectonic plates that are moving apartB. Along the boundary of tectonic plates that are moving togetherC. Along the boundary of two different countries

Question 3. Below are two satellite images of Lake Chaquita in Argentina. The image on the left was taken in 1998 and the image on the right in 2011.

Image credit: NASA State of Flux website (accessed June 21, 2013) http://climate.nasa.gov/state_of_flux#Mar_Chiquita_930x461.jpg

What might have caused the changes to Lake Chaquita between 1998 and 2011? Check the box next to each of the things that may have caused the changes shown above.

☐ An increase in the amount of agriculture in the region☐ An increase in the amount of rainfall in the region☐ Lower average temperatures in the region☐ Long periods of drought during that time period☐ A dam was built on a river that flows out of the lake

Question 4. Below is a map that shows the depth of the bottom of a lake.

Image credit: https://your.kingcounty.gov/dnrp/wlr/water-resources/small-lakes/data/LakePage.aspx?SiteID=17 (accessed June 21, 2013)

On the map above, do the following:Draw an X at the deepest point in this lakeDraw a circle around an area where the lake floor depth change is steepDraw a box around an area where the lake floor depth change is gradualWrite the word “BEACH” in a good place for a swimming beach

Question 5. Name two things that can influence the amount of sediment deposited at the bottom of a lake.

Question 6. What are two things that you can learn about a lake by studying the sediments from the bottom of a lake?

ANSWER KEY for Pre-/Post-Assessment

Teacher Note: Correct answers are in bold or italics.

DirectionsQuestion 1-2. Circle the letter of the answer that best answers each question.

1. How are glacial lakes formed?A. They form when glaciers crash into each otherB. As glaciers move, they grind away soil and rock to form lakesC. They are formed on the top layer of glaciers when ice melts

2. Where do rift lakes generally form?A. Along the boundary of tectonic plates that are moving apartB. Along the boundary of tectonic plates that are moving togetherC. Along the boundary of two different countries

3. Below are two satellite images of Lake Chaquita in Argentina. The image on the left was taken in 1998 and the image on the right in 2011.

Image credit: NASA State of Flux website (accessed June 21, 2013) http://climate.nasa.gov/state_of_flux#Mar_Chiquita_930x461.jpg

What might have caused the changes to Lake Chaquita between 1998 and 2011? Check the box next to each of the things that may have caused the changes shown above.

An increase in the amount of agriculture in the region☐ An increase in the amount of rainfall in the region☐ Lower average temperatures in the region Long periods of drought during that time period☐ A dam was built on a river that flows out of the lake

4. Below is a map that shows the depth of the bottom of a lake.

Image credit: https://your.kingcounty.gov/dnrp/wlr/water-resources/small-lakes/data/ LakePage.aspx?SiteID=17 (accessed June 21, 2013)

On the map above, do the following:Draw an X at the deepest point in this lakeDraw a circle around an area where the lake floor depth change is steepDraw a box around an area where the lake floor depth change is gradualWrite the word “BEACH” in a good place for a swimming beach

X

BEACH

5. Name two things that can influence the amount of sediment deposited at the bottom of a lake.

Human activity, such as agriculture, irrigation, dams, and recreationThe amount of precipitation in the areaThe amount of living things in the areaThe flow of rivers into a lakeGeological activity in the region

6. What are two things that you can learn about a lake by studying the sediments from the bottom of a lake?

Changes in the climate near the lake over timeChanges in the biological activity in the lake over timeHow long ago sedimentary layers were deposited (varve counting)Human impact on lakes over time (beaches, dams, irrigation,

agriculture, etc.)