- What percentage of animals will become fossils?
- The geologic time scale divides Earth's history into intervals based on what?
- Which part of organism will more likely fossilize?
- T/F There was no multicellular life prior to the cambrian explosion
- Earth's atmosphere changed dramatically w/the introduction of free oxygen approximately _____ years ago. A second oxygenation event began _____ years ago and brought the atmospheric concentration to its approximate current level of 20%
- Name the organism and process responsible for oxygenating Earth's atmosphere
- If a creature has hard parts and is rapidly buried after death, it is more likely to become a(n) _____
- The Mesozoic Era is known as the age of the _____, after the best-known creatures of this age
- True or false: Cross-cutting relations can be used to determine that the Colorado River cut through the Grand Canyon after the sedimentary rocks formed
- The Cenozoic Era is called the age of _____ because of their abundance and diversity during this time
- What defines the boundaries between each of the three eras in the geologic timescale?
- The age of Earth is estimated ti be 4.55 billion years. This is determined by dating _____
- Dikes, sills, veins, and fractures are features that can be used in the principle of _____ to determine the relative age of geologic events
- Dating rocks using radioactive isotopes that decay over time is called _____ dating
- Trilobites first appeared on Earth during the _____ Period, when a so called _____ of life (rapid evolutionary change) introduced many new species in a short time frame
- Give an example of a form of life in this time period: Late Paleozoic
- Rapid burial of a dead organism helps to preserve it from being destroyed through _____
- Isotopic dating of basement rocks in _____ suggest Earth has a long history because the oldest rocks, from the area of the Canadian Shield, are more than 3 billion years old
- Old sedimentary rocks that are _____ in color indicate the presence of oxygen in Earth's early atmosphere and oceans
- The periods of the geologic timescale are named after regions in Europe. For example, _____ is derived from Cambria, and _____ is derived from the Jura Mountains