1. Geologic Time

2. “Consider the Earth’s History as the old measure of the English yard, the distance from the king’s nose to the tip of his outstretched hand One stroke of a nail file on his middle finger erases human history.” John McPhee, 1980, Basin & Range

3. Absolute or Relative? Anthony is the youngest. Melony is 4 years old. Michael is older then Sasha. Sasha is 16 years old. Ashley is older than Melony, but younger than Sasha.

4. Relative Dating Used to determine the order of events and the relative age of rocks by looking at the position of rocks in a sequence Numbers are not used Ex: “I am older than you.”

6. Law of Superposition In an undisturbed layer of rock, the oldest rocks are on the bottom and the younger rocks are toward the top

9. Law of Original Horizontality Layers of sediment and lava are deposited in horizonatal sheets. If layers are not horizontal, they have been moved

12. Folding

15. Law of Inclusions Inclusions are rocks, crystals, or fossils in another kind of rock. Any inclusion is older than the rock that contains it.

18. Law of Cross-Cutting Any feature that cuts across a rock or sediment must be younger than the rock through which it cuts. Faults, veins, and igneous intrusions

26. Unconformity Gap in the geological record –Due to erosion –Layers not deposited –Sediment on igneous or metamorphic rock

32. Clues from Fossils Fossils in layers of rock show definite order. Index fossils

37. ID ages of different rocks