Why are time periods on the geologic time scale no even in length?
They are based on the type of fossils found in rock layers of the earth.
They are based on important events that happened in earths history.
They are based on a different type of calendar used to track earths history.
They are based on the thickness of the earths rock layers.
The correct answer is: They are based on important events that happened in earth's history.
Time periods on the geologic time scale are not based on the length of time, but rather on significant events or changes that occurred in Earth's history. These events, such as mass extinctions or the formation of major geological features, are used as markers to divide Earth's history into different time periods. The length of each time period can vary greatly, as it is based on the occurrence of these important events rather than on a consistent measure of time.
Time periods on the geologic time scale are not even in length because they are based on important events that happened in Earth's history. The divisions of the geologic time scale are defined by significant geological or biological events, such as mass extinctions or the appearance of new species. These events mark major shifts or changes in the Earth's geological or biological makeup, and therefore, the boundaries of the time periods are not evenly spaced. The length of a time period can vary depending on the significance and duration of the events that define it.
The correct answer is: They are based on important events that happened in Earth's history.
The geologic time scale is divided into different time periods to help scientists understand the history of our planet. These time periods are not of even length because they are primarily based on important events that happened during Earth's history. These events can include mass extinctions, major geological events (such as the formation of certain mountains or the opening and closing of ocean basins), and other significant changes that occurred in Earth's natural processes.
To determine the boundaries and durations of these time periods, scientists use various methods, including analyzing the fossil record, studying rock layers, and investigating the isotopic ages of certain rocks or minerals. By examining the types of fossils found in specific rock layers, scientists can correlate different areas around the world and establish a relative age for these fossils. The occurrence of certain fossils or the absence of others can help identify specific time periods.
Additionally, studying important events and changes in Earth's history, such as climate shifts or the impact of large asteroids, helps geoscientists determine when and how these events occurred and their impact on the planet.
So, while the thickness of Earth's rock layers can provide some information about the relative duration of certain time periods, it is the significant events and changes in Earth's history that primarily determine the boundaries and lengths of the geologic time scale.