Warmup Week 16 Day 2 1 Sedimentary rocks

Warm-up Week 16 Day 2 1. 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 2. 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 3. a. Index fossils allow geologists to ____. match rocks of the same b. identify organisms that did age in different regions not leave fossil evidence determine rocks’ exact age d. determine why some organisms became extinct c.

“Radioactive Dating & Geologic Time Scale” 12. 3 & 12. 4

Review. “Atoms. ” Smallest particle of Element.

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

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

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

1. Radiometric Dating – Isotopes decay at constant rate – Calculate “birth” of Parent Isotope 2. Radiocarbon Dating – Carbon-14 isotope – All living things – Ratio of Carbon 12: Carbon 14 gives “death” date.

Review: How do we know…? 1. 2. 3. 4. Relative Dating Fossils Radiometric Dating Radiocarbon Dating So, Now What? . . .

Geologic Time Scale 1. Eons 2. Eras 3. Periods 4. Epochs

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