Lesson 5: Turnover and Upwelling


Activity 1: Hydrologic Sorting

Materials: 3 soil samples from the local area, one-quart clear jar with lid
For this activity, you are going to observe a process known as hydrologic sorting. While the term hydrologic sorting sounds complicated, it simply means sorting by water. You will begin to learn about sorting by water using materials from your local area — a backyard, a creek bed, or wherever you have permission to collect soil. You will use the sample you collect to conduct an investigation (be sure to keep the sample after this initial activity).

Follow the instructions below to complete your experiment:
  1. Collect soil samples from three different areas. Each sample should be between one half and a full cup. Be sure to look for different soil types (mud, potting soil, sandy soil, etc.).
  2. Fill a clear jar (at least one quart) with water until the water is about two inches from the top. NOTE: Be sure that you have the top for the container.
  3. Put all three soil samples in the container of water and place the lid tightly on the container.
  4. Shake the container until the water and soil are thoroughly mixed together.
  5. Predict what will happen to the soil. Sketch and explain your prediction on the "Hydrologic Sorting" page.
  6. Put the container to the side and allow it to settle.
  7. Once the container's contents have settled (after about 2 hours), sketch what you observe. Also answer the question in the "Make a Connection" box.
  8. When you have completed the experiment, set the container and its contents aside for use in Activity 2.
Student Activity Page
For this activity, your child will be working on observation and induction — developing general principles from observing a specific event. The results of the sorting activity will be two-fold. First, the soil will settle out of the water and collect at the bottom of the container. Second, your child will be able to observe the presence of layers.

The layers are significant because they represent differences in the soil that your child collected. The bottom-most layer is made up of the heaviest particles. The top-most layer is made up of the smallest particles. Your child should be able to see the layering occurring in a couple of hours, so instead of splitting the lesson into two days, you may want to have your child start the sorting activity, take care of other lessons, and then return to the sorting container after about two hours. The goal is for your child to start making a connection between the experiment and what happens with sediment that is in lakes, oceans, and other bodies of water that are calm.

Making the Connection: What is the importance of this process for life in lakes and oceans? Answer: Matter that is in water will settle based upon its density. Heavier particles settle more quickly and collect at the bottom of the lake. Later layers collect based on the size and weight of the particles. This process of hydrologic sorting and sedimentation is significant because sediment that does not settle blocks sunlight and affects the growth of plants. Suspended sediment also affects water temperature, which makes a difference in how nutrients and other materials circulate in the waters.