Erosion and Deposition

Before you begin the scientific investigation below, make sure to download the Graded Bedding Scientific Investigation Report. As you complete this scientific investigation, fill in any needed information on the report template. If you need more information about each section of the report, please visit the Developmental Module.

This scientific investigation is available below or in a printable version.

Introduction

Most sedimentary rocks are millions of years old. As a result, no humans were around to document the processes that lead to the formation of these beds of rock. How can geologists distinguish sedimentary rocks that were deposited by wind in a desert from rocks deposited by a body of water? The answer is found in special depositional features like cross-bedding and graded bedding.

Objectives

In this scientific investigation, you will:

• observe how sediments settle in a body of water; and
• evaluate depositional environments based on features in the sediment.
  

Hypothesis

Using the Procedure and Data Collection section below, read through the procedural information for this scientific investigation. Based on your understanding of the procedure, develop your own hypotheses which describe what you think you will see when you drop a sediment sample containing several different sized items into water. Hypothesize about which items you think would fall faster or slower. Record these hypotheses in the Hypothesis section of your Graded Bedding Scientific Investigation Report.

Procedure and Data Collection

1. Collect a sample of soil from outside. This sample should include soil, pebbles, rocks, and any other items found during the collection process.
2. Fill the jar or beaker 3/4 full with water.
3. Analyze your sediment sample by looking at it closely. Using a hand lens or magnifying glass to analyze the sediments is recommended. In the Data section of your Graded Bedding Scientific Investigation Report, sketch the sediment sample, making sure to observe if the sediments in the sample have smooth edges or round edges. Compare the size of the sediments in the sample.
4. Add one spoonful of your sediment sample to your jar, and using your stopwatch, record the time it takes your entire sediment sample to reach the bottom. Make sure to record any observations during this step. You may also choose to record this process for later observation.
   

Data

Use the spaces provided in the Data section of your Graded Bedding Scientific Investigation Report to record your data from this scientific investigation.

Data Analysis

In the Data Analysis section of your Graded Bedding Scientific Investigation Report, provide responses to the following questions:

1. What happened to the sediment, based on sediment size?
2. Which sediment settled the slowest? Why?
3. Which sediment settled the fastest? Why?
4. How do you think your results would have changed if you were stirring the water in the jar while the sediments were falling?
5. Identify the depositional feature that you have modeled, and identify which kind of environments on Earth would produce deposits with this pattern of sedimentation.
   

Conclusion

Using the Conclusion section of your Graded Bedding Investigation Report, compose three to four sentences describing an overall conclusion based on your data. Were your hypotheses true or false, and how do you know? Use the data and notes that you collected from your investigation to form your conclusion. Make sure that you include information that you gained from data analysis to support your conclusion.

Experimental Sources of Error

On your Graded Bedding Scientific Investigation Report, provide responses to the following questions: Are there any sources of error? If so, what are they, and what could be done to minimize error?

Once you have completed your Graded Bedding Scientific Investigation Report, please submit your work to the dropbox.