Aura Perine Michael Kass Geology 1010 “How do geologists know how old a rock is?” This semester I learned so much in my Geology class. So much, that it was very difficult for me to decide what to share on my e-Portfolio. From volcanoes, earthquakes, sedimentary/igneous/metamorphic rocks, to mountain building and geologic time. I was able to attain a general understanding of such an incredible field of physical science. Though I was able to learn about several different studies and forms of research within the geologic and paleontological fields on a fairly broad base, I can say that I now have a much greater appreciation for the planet Earth that I live on and its numerous processes that it has undergone, and continues to undergo since it was estimated to be created, 4.5 billion years ago. Attached is a page from a lab assignment that I completed as part of the class. The lab assignment was based off our studying the concept of geologic time. As part of geologic time, we learned of the Law of Superposition, which was established by geologist Nicolaus Steno. The Law of Superposition states that “in an outcrop of an un-deformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below.” (Earth—An Introduction to Physical Geology.) In the lab assignment, I was to identify and label each layer of sedimentary rock, using the Law of Superposition. Each layer is labeled chronologically.