Forensic Geology Lab: Digging Through the Sands of Crime

In this hands-on geology lab, students with visual impairments explore index fossils and analyze data to solve a mystery.

As you know fossils are clues that allow us to see all the changes that happened throughout earth’s history, such as climate, weather, foods, etc. Index fossils are clues for a specific era of time, such as the Pre-Cambrian period. In this lab there is a strange twist worthy of the great Sherlock Holmes (well, assuming you know who he is). Apparently ________, a geology professor from Purdue University, was found with a shell in her lab coat, during a random search for empty Skittle bags. (Those administrators have nothing better to do than be on candy patrol). What is odd is that the particular mollusk found in her pocket is an index fossil, and the species is from an archeological dig site that is off limits to the public, ever since a strange metallic fin was found buried one foot below the surface. No evidence is allowed to be removed from this site.

_________ (AKA “Queen of the participle”) has accused four of her fellow professors of professional jealousy, stating that they have acted in an unprofessional manner, but re-arranging evidence. Each colleague has stated under oath that they were digging on the same day, but at different geologic depths, were seen by each other, emptied their pockets before they left, and could not have done what _________ has said.

Here is was the detectives have discovered. For purposes of this lab, one centimeter each in depth equals three million years:

  1. Professor ________________ was digging at a depth of 4 centimeters.
  2. Assistant Professor Braille Dot______ was digging at a depth of 8 centimeters.
  3. Dr. I.M.______________ was digging at a depth of 12 centimeters.
  4. Professor Emeritus ________was working at a depth of 14 centimeters.

NOTE: It was not determined as yet where _________ was excavating.



  1. Create a cardboard that has each actual shell (“fossil) labeled in Braille and Large Print. Label the shell by its Genus-Species name. Explain that the shell number indicates its depth in the sand by its age. State that these are index fossils, that is a specific fossil that is found worldwide at that depth.
  2. Purchase clean, playground sand, plastic tubs, various kinds of painting brushes and scoops.
  3. Have buckets nearby for students to place sand that has been scooped or brushed out.
  4. Have students place newspaper under the pans for easier cleanup.
  5. Caution students to brush and scoop slowly to avoid digging up a fossil at the wrong depth. When students come to the top of a fossil, use the brush.
  6. Make sure students measure accurately the depth of the fossil. This will come in handy as they review the data table.
  7. Fill in the blanks with the student’s favorite or non-favorite teachers or staff.
  8. Expect to take 4-5 days to complete the lab.


  1. Using the brush, sweep away and remove the first layer of sand until you find the first fossil.
  2. Measure the depth of the fossil.
  3. Carefully remove the fossil with a scoop, set it aside, catalogue it with your fossil board and continue digging until you reach the bottom of the pan.

Data Table 1: Down to the bottom

Depth (cm) Fossil
Fossil Time Period
Key to Index of Fossils
Click to download Key to Index of Fossils
  1. Examine the fossil found in _________’s lab coat, and the other fossils found at the depths each professor was digging. One fossil was found at the wrong depth. This will be used to catch the professor who altered the site.

NOTE: Each centimeter in depth represents one million years of geologic time.

Data Table 2: Fossils found in the sands of crime

Professor Fossil






The professor who altered the dig site was: _________________


  1. How did you determine which geologist was guilty?
  2. What are index fossils?
  3. What are the characteristics of an index fossil?
  4. Why did you use a brush to uncover fossils?
  5. Why is geologic time helpful in determining the age of fossils?

Bonus: Discuss why some organisms never appear in the fossil records.


  1. Make the digging more difficult by adding rocks and fossils NOT on your fossil chart.
  2. Wet several of the different sand layers (and let it dry) for creation of a “real-life” fossil dig.
  3. Assign roles to each group member and job description: Head archeologist, Data Collection Specialist, Site Artist, Report Writer, etc. 

NGSS Standards:

Analyzing and Interpreting Data

Constructing Explanations and Designing Solutions

Obtaining, Evaluating and Communicating Information

By aroth

Return to Accessible Science main page.

PIAF machine: A "P" alphabet braille page (pig with braille and print letter P) being entered into a PIAF machine.

Creating Tactile Graphic Images Part 3: Tips for Embossing

SkippyNums app logo (jump rope and text, "SkippyNums"

Field test SkippyNums: an accessible skip counting app

Tech Tea Time logo and text, "Document Accessibility - Math"

MathType, JAWS, and BrailleNote Touch