Volcano: Cup off the top of a water bottle and then form the volcano around it with brown fondant.
Dinosaurs: Dinos can be molded out of fondant
Sand: Cover your base with crushed graham cracker crumbs
Cake: The design on the top of the cake is drawn in colored, melted chocolate (see instructables tutorial here)
Water: Spread white frosting on your cake board to create waves and then cover with blue piping gel. Pipe grass and ass candy rocks along the boundary of the lake.
Step 1: Prep the Volcano
Mix together water and red (ex. strawberry) jello mix and fill the water bottle 3/4 full. Add a piece of dry ice and watch it erupt.
Step 2: Eruption
At first the volcano will "smoke" and then the jello mixture will start to bubble up and ooze reg goo. Click here to view a video of the volcano in action.