Name: _______________________ # ______ Date: ____________________ Core: ______ A Walk Through Time Lab Sometimes geologists want to know about an event that occurred before humans were around to record it. They have evidence of when the event occurred by looking at rocks, which contain fossils and other information. To keep all of the events in order, geologists have created the geologic time scale. The geologic time scale is divided into 3 eons, and each eon is subdivided into eras. Eras are then subdivided into periods, which are then further separated into epochs. This may sound confusing, but the Earth has been around for a long time and a lot has happened! The Earth formed about 4.6 billion years ago (4,600,000,000) years ago, so to put geologic time into terms that are easier to comprehend, we’re going to imagine that the entire history of Earth fits onto a football field. Materials Geologic Time Scale Geologic Time Football Field Colored pencils Calculator Procedure Step 1 Choose 4 different colored pencils to represent each of the geologic times. Lightly color the box in Table 1 below for the geologic time that each color will represent on your football field. Step 2 Complete Table 1 below to determine the beginning and ending dates of the Precambrian Time and each of the eras that followed. Each yard on the football field represents 46 million years in geologic time. Table 1 Geologic Time Period Precambrian Time Paleozoic Era Mesozoic Era Cenozoic Era Began Distance (yds) 4.6 billion years ago 570 million years ago 245 million years ago 66.4 million years ago Ended Distance (yds) 570 million years ago 245 million years ago 66.4 million years ago present Step 3 Beginning at the end zone labeled “Today” on your football field, count the number of yards away from the end zone that would represent the beginning of the Precambrian time and mark it. Each of the lines on the football field is 1 yard. Step 4 Beginning at the end zone labeled “Today” on your football field, count the number of yards away from the end zone that would represent the end of the Precambrian time and mark it. Step 5 Lightly color all of your football field that represents the Precambrian time period with the colored pencil you chose to represent it. Step 6 Repeat steps 3-5 for each of the eras on the chart as well. Name: _______________________ # ______ Date: ____________________ Core: ______ Step 7 Complete Table 2 below to determine when each of the geologic events in Earth’s history occurred. Each yard on the football field represents 46 million years in geologic time. Table 2 Geological Event Approximate Age Appalachian Mountains form 1.1 billion years ago Earth forms 4.6 billion years ago Himalayas form 50 million years ago Pangaea forms 300 million years ago Pangaea splits apart 200 million years ago Peak of the last ice age 20,000 years ago Oldest known rock 4.2 billion years Distance (yds) Step 8 Beginning at the end zone labeled “Today” on your football field, count the number of yards away from the end zone that would represent when the Appalachian Mountains formed, mark it, and label it. Step 9 Repeat step 8 for each of the other geologic events in Earth’s history. Step 10 Complete Table 3 below to determine when each of the biological events in Earth’s history occurred. Each yard on the football field represents 46 million years in geologic time. Table 3 Biological Event Columbus discovers America Approximate Age 522 years ago Earliest humans appear 2 million years ago Extinction of the dinosaurs 65 million years ago First amphibians appear 375 million years ago First birds appear 160 million years ago First dinosaurs appear 230 million years ago First fish appear 510 million years ago First mammals appear 200 million years ago First multi-cellular organisms appear 700 million years ago First plants appear 498 million years ago First reptiles appear 325 million years ago First single-celled organisms appear 1.2 billion years ago Modern humans appear Distance (yds) 200,000 years ago Step 11 Beginning at the end zone labeled “Today” on your football field, count the number of yards away from the end zone that would represent when Columbus discovered America, mark it, and label it. Step 12 Repeat step 11 for each of the other biological events in Earth’s history. Name: _______________________ # ______ Date: ____________________ Core: ______ Summary 1. Where would your birth date be on the football field? Why is it almost impossible to show a human’s life on this scale? Would it be easier if we changed the number of years that 1 yard represents? 2. Complete the chart below using your football field AND geologic time scale. Organism Era Period amphibians birds fish modern humans plants reptiles 3. How many years are represented by 10 yards? What events are within the first 10 yards of the football field from the “Today” end zone? 4. Look at your geologic time scale. Why do you think the Phanerozoic Eon has many more divisions and dates associated with in than the Archean Eon? Name: _______________________ # ______ Date: ____________________ Core: ______ Name: _______________________ # ______ Date: ____________________ Core: ______