Earth Events

1. changes in life Earth is a Dynamic and Evolving Planet • changes in its surface

2. 3 Main Themes Plate Tectonics Evolution Uniformitarianism

3. Uniformitarianism • Uniformitarianism is a cornerstone of geology • present-day processes have operated throughout geologic time • physical and chemical laws of nature have remained the same through time • to interpret geologic events • we must first understand present-day processes and their results • rates and intensities of geologic processes may have changed with time

4. Historical Geology • In historical geology we study • changes in our dynamic planet • how and why past events happened • implication for today’s global ecosystems • Principles of historical geology • aid in interpreting Earth’s history • also have practical applications

5. Geologic Time • Human perspective • seconds, hours, days, years • Ancient human history • hundreds or even thousands of years • Geologic history • millions, hundreds of millions, billions of years

6. Geologic Time Scale • Resulted from the work of many 19th century geologists who • pieced together information from numerous rock exposures • constructed a sequential chronology based on changes in Earth’s biota through time • started as a relative time scale • The time scale was subsequently dated in years using radiometric dating techniques

7. Geologic Time Scale

8. How Does the Study of Historical Geology Benefit Us? • Survival of the human species depends on understanding how Earth’s various subsystems work and interact • how we consumenatural resources and interact with the environment determines our ability to pass on this standard of living to the next generation • our standard of living depends directly on our consumption of natural resources that formed millions and billions of years ago • Study what has happened in the past, on a global scale, to try and determine how our actions might affect the balance of subsystems in the future