River Formation Experiment

Recently in science class we have been doing river formation experiments with diatomaceous earth. We mixed it up the first day and then let it sit and even out until the next day. We mixed it again to get rid of all the puddles in it. Once we leveled it out again we did a flat experiment. We left the tub flat on the counter and poured water onto one point. It eroded a small hole where the water was coming down but then it would even out and spread smoothly. Then we drained and filtered the water and tried the experiment again but with one side lifted up. The water again dug out a hole where it was pouring onto it then quickly dug out a line all the way down the tub like a river. The next day we put in water beakers to act like buildings and tried it at an elevation. the water didn't move as fast but made small tributaries around the "buildings." After draining and filtering again we put in foam blocks acting as a dam across most of the tub. We found that the water quickly goes to the dam the slowly goes around then speeds up to the bottom of the tub. It formed a small river in the opening of the dam but then it went away and the water just spread out freely.