Climate Clues from Sand and Mud

Part A: Particle Size and Rate of Deposition

What types of sediments are there?

There are three types of sediment. Most sediments are produced by wind and water breaking down rocks and minerals. These are called clastic sediments sediments composed of fragments, or clasts of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. . But sediments can also form directly in bodies of water. When the concentration of minerals like calcium and magnesium is high in warm water, the minerals can precipitate out to form deposits called evaporites a sedimentary rock formed by evaporating sea water.. These are called chemical sediments sediments composed of previously dissolved minerals that have either precipitated from evaporated water or been extracted from water by living organisms and deposited when the organisms died or discarded their shells. . The Bonneville Salt Flats, shown in the picture on the right, formed in this manner.

Finally, tiny organisms called foraminifera and coccoliths secrete calcium carbonate; others, called diatoms and radiolarians, secrete silica. When these organisms die, their shells fall to the ocean floor and form biochemical sediments sediments formed from the gradual accumulation of biologic material such as shells or dead plant material..

Explore sediment types and settling rates

In the following lab you will explore sedimentation rates. Begin by reviewing the lab procedure and building a data table to record your results.
Assemble the following materials:

• Play sand
• Craft sand
• Flour
• Measuring cup
• A spaghetti sauce jar (or similar clear glass or plastic container) with a tight-fitting lid

Lab Procedure

Your teacher will distribute a lidded jar and 3 or 4 types of sediment (aquarium gravel, coarse sand, craft sand, and flour) to you.

1. Fill the jar 3/4 full of water.

2. Drop in a pinch of one type of sediment. Watch it fall. Time the length of the fall.

3. Record the settling rate in the correct column on your sediment characteristics data table.

4. Repeat step 2 for the other sediment types.

5. Mix the following dry ingredients in a large beaker, measuring cup, or graduated beaker:

• ¼ cup (60 ml) of play sand
• ¼ cup (60 ml) of craft sand
• ¼ cup (60 ml) of white or wheat flour
• ¼ cup (60 ml) aquarium gravel (optional)

6. Fill a jar (with a top) about 2/3 full of water.

7. Close the top of the jar and shake vigorously a few times. Record the settling order in your data table. You may want to wait for ten minutes or until the next class period to do step 8. Note: In nature, the settling rate is called the sedimentation rate the time it takes for a certain amount of sediment to be deposited on the sea floor (cm/year).—the time it takes for a certain amount of sediment to be deposited on the sea floor (cm/year).

8. Draw a sketch of the layers in your jar and label each one.

9. Answer the following Checking In and Stop and Think questions.