In this activity, dikes tend to propagate radially from the center of bowl-shaped casts of gelatin because the resistance to opening is the same in every direction. The dike opens in the narrow dimension and we see propagation in the long dimemsion. With a slow, steady injection rate, the colored water creates a dike and generally erupts from the flanks or ends of the gelatin casts. Edge-on, a dike appears as a line. When the gelatin cast is sliced through with a knife, dikes appear as red lines in the vertical, cut edges.
Preparation Follow the directions listed on the student sheet for preparing the gelatin.
Gelatin requires at least three hours of refrigeration to set. Use a warm water bath to free the gelatin from the bowl without getting water on the gelatin itself. Unflavored gelatin is ideal for this experiment because of its transparency. Sweetened gelatin desserts also work. If you prefer the dessert variety, then use a flavor that is easy to see through, such as lemon.