Presentation on theme: "Do Now 8/19/11 How does the existence of homo-sapiens (100,000 years ago) compare to the length of the earth? How does the impact humans have had on the."— Presentation transcript:
1 Do Now 8/19/11How does the existence of homo-sapiens (100,000 years ago) compare to the length of the earth? How does the impact humans have had on the earth compare to the impact of other species? Explain.
2 Geological Timescales and Catastrophic events 8/19/11
3 What is a Geological Timescale? A scale of the history of the earth, supported by geological/archeological evidence.
4 What are two ways that scientists can tell how old the earth is? Radiometric dating and Relative dating using fossils.
5 What is Relative Dating of Fossils? Using The law of superposition to compare ages of fossils.
6 What is radiometric dating? The use of isotopes (like carbon 14) to tell us the absolute date of a fossilized organism.
7 How do scientists divide the geologic timescale into eons, eras and periods? By major events, such as extinctions.
8 What might cause a major extinction? A catastrophic event might cause a major extinction, like the dinosaurs.
9 What are some catastrophic events? VolcanoesEarthquakesMeteor showersSevere temperature changes (ice ages, global warming)