Explain to the students that the ingredients they are adding represent sediments of material. As you add each ingredient to the mixture, they are becoming compacted together. After all of the ingredients are added, you have something similar to a sedimentary rock formation. When you form the small, teaspoon size drops of dough on the cookie sheet, you have compacted the ingredients together to form a solid material. You can discuss how this is similar to conglomerate rock.
Conglomerate rocks are sedimentary rocks.
They are made up of large sediments like sand and pebbles. The sediment is so large that pressure alone cannot hold the rock together, but are cemented together with dissolved minerals. The chips and nuts can represent the large sediments and the dough represents the dissolved minerals that cement the rock. Next have the students predict what will happen to this dough when heat is added to this mixture. Tell the students that this is how sedimentary rock is changed, or morphed, into another kind of rock.