Making Sandstone and Conglomerate: An Introduction to Sedimentary Rocks

By Gregory Paul Pavlik

Grade Level: 7 -12

Background Information:

This activity will demonstrate the lithification process of sedimentary rocks.


  • Sand Water Mason jars w/ lids ( 1 per group)
  • Gravel Glue Petri plates ( 1 for every two students )
  • Mason jar rings ( One for every student )
  • 250 ml beakers Screen ( will be cut to fit inside the jar rings )
  • Stirring rod


Day 1

  • Introduce the concept of the rock cycle. Especially the processes of weathering, erosion, and deposition.
  • Activity: Sedimentary deposits

In a Mason jar fill approximately half full with water. Then add 1/2 cup of a mixture of sand and gravel. Place the lid on the jar and shake. Let the jar stand for 10 minutes. During this time have the students make predictions of how they expect the particles to separate. After 10 minutes add 1/4 cup more of the sand/gravel mixture. DO NOT MIX a second time!!! Have students record their observations.

Day 2

  1. Have students prepare a glue mixture. (The mixture that has worked best for me is a glue to water ratio of approximately 5:1. This mixture can not be too thick. If the mixture does not run through the sand shortly after pouring it , it is too thick ) Let the mixture sit until later.
  2. Obtain a piece of screen and cut it to fit inside the jar lid.
  3. Fill the jar lid with the sand or gravel mixture. (I have half the students use the sand mixture and half use the sand/gravel mixture)
  4. Place jar lid on top of the petri dish, then carefully pour part of the glue mixture evenly on top of the mixture they have in the jar lid. Allow the glue mixture to percolate throughout the mixture. Then repeat this procedure several more times. Allow the jar lid/petri plate to remain undisturbed until it dries completely. (At least 2 days)
  5. After the mixture has dried have students compare what they started with to the newly formed sedimentary rock. Have students explain what the water/glue mixture represents in nature. Where is the cementing agent found in nature?

Teacher's note: The longer you can let these stand the better off they are.

Extension Activities:

Have students mass the sand or sand and gravel mixture before they add the glue mixture then mass again after dried to get an idea of the amount of cementing material is needed to form a sedimentary rock.

Expose the man-made sandstone/conglomerate to artificial weathering...

For example.

  1. Allow water to drip on it overnight and observe any changes
  2. Place a sample under a lamp for an extended period of time.
  3. Place a sample in the freezer for an extended period of time.
  4. Alternate a sample between the lamp and freezer over an extended period of time.
  5. Place a sample outside and expose it to natural weather conditions and make observations over time.

Compare student made samples to natural samples. Measure the mass of 2 similar sized samples and address any major differences observed.