Backyard Dig

1. Backyard Dig By Samir Chethan, Areej Othman, and Gretchen Schiek

2. Description When we dug in our backyard we found 4 rock layers. First we found pumice so we dug around it. Next, we found basalt a few feet under the pumice, next we found sandstone, then shale, and nothing after it, but dirt. Due to the law of superposition, we knew that shale was the oldest, then sandstone, then basalt, and the youngest was pumice.

3. More Desciption After taking a small sample of each rock, we found a fossil in the pumice, the basalt, and the sandstone. In the sandstone we found a trilobite fossil, a paleozoic creature, in the basalt we found a baby pterodactyl, a mesozoic creature, and in the pumice we found a human, a cenozoic creature. Each had a cast and a mold, neither contain the actual creature, but the difference is that the cast has the actual shape and texture of the creature, and the mold has an indent of the creature’s shape.

4. Research These creatures were once alive, but were eventually covered with some substance giving a mold of the animal, but the creature decomposed. From my research, I now know that our backyard was once covered with water during the paleozoic age, the watered dried up and then it became hard land during the mesozoic age and stayed that way until current day.

5. Rocks/fossils Pumice Cenozoic Skull Skull Pterodactyl Pterodactyl Basalt Basalt Mesozoic Sandstone Paleozoic Shale Precambrian Trilobite Trilobite