Rocks and Minerals > Rock Cycle Activities

Sedimentary Rocks: Constructing Conglomerate

by Deborah Hanuscin

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Concept: Conglomerate formation

Conglomerate is formed through the processes of weathering, transport, deposit, burial, and lithification, as described in Sedimentary Snack Bars. It is made up of chunks of sediment that are larger than sand-size (greater than 2 mm), such as pebbles, that are bound together by a cement.

Objective:

Students will be able to define conglomerate and explain how it is formed.

Materials:

• tablespoon
• fine sand
• paper cup
• pebbles
• coarse sand
• calcium hydroxide (slaked lime—available at hardware stores)
• water

Procedure:

1. Place several tablespoons of fine sand in a paper cup.
2. Add several tablespoons of coarse sand and pebbles and mix.
3. Add calcium hydroxide.
4. Add enough water to moisten the mixture and set the cup where it can remain undisturbed for several days.
5. After the water has evaporated, carefully tear away the paper cup.

Questions:

1. What is conglomerate? How does it form?
2. How does your conglomerate compare to other sedimentary rocks?

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