1. Warm-up Week 16 Day 2
Sedimentary rocks record past geological events and ___.
a. changing life forms of the past b. written history
c. Earth’s circumference and d. astronomical
diameter in the past milestones
The dating process that places geologic events in proper sequence is referred to as a ____.
a. numerical dating c. relative dating
b. temporary dating d. radiometric dating
Index fossils allow geologists to ____.
match rocks of the same b. identify organisms that did
age in different regions not leave fossil evidence
c. determine rocks’ exact age d. determine why some organisms became extinct

2. “Radioactive Dating & Geologic Time Scale”
12.3 & 12.4

3. Smallest particle of Element.
Review.
“Atoms.”
Smallest particle of Element.

4. Nucleus.
“Electron Cloud”
Center of Atom. P+ No
Outside Nucleus. E-

5. Isotope.
Atom with diff. #’s P+ and No
Radioactive Decay.

6. Radioactive Decay Isotopes  Stable atoms “Half-Life”
Parent  Daughter
Release Energy
“Half-Life”
Time for ½ of nucleus  stable.

7. Radiometric Dating Radiocarbon Dating Isotopes decay at constant rate
Calculate “birth” of Parent Isotope
Radiocarbon Dating
Carbon-14 isotope
All living things
Ratio of Carbon 12: Carbon 14 gives “death” date.

8. So, Now What?... Review: How do we know…? Relative Dating Fossils
Radiometric Dating
Radiocarbon Dating
So, Now What?...

9. Geologic Time Scale
Eons
Eras
Periods
Epochs

10. Early Earth was VERY different from Earth today.
Evidence Suggests…
Early Earth was VERY different from Earth today.