1. GEOLOGIC PRINCIPLES & RELATIVE DATING

2. HOW OLD IS THE EARTH? The Earth is about 4.6 billion years old Much of its history is recorded in the rocks Observations of fossils, rock types, evidence of faulting, uplift, and folding as well as igneous activity are all clues about the earth’s history

6. THE KEY TO THE PAST Relative Time- “this rock is older than that” Principles Used to Determine Relative Age Unconformities Correlation The Standard Geologic Time Scale Index Fossils Absolute Time- “this rock is 28 million years old” Principles of radioactive decay Instruments The age of the Earth

7. JAMES HUTTON 1 ST GEOLOGIST “from what has actually been, we have data for concluding with regard to that which is to happen thereafter.” “All inferences from experience suppose…that the future will resemble the past” Because of many of his ideas, he was thought to be atheistic.

8. IMPORTANT RELATIVE AGE DATING PRINCIPLES Brothers, sisters, first cousins are off limits! It may lead to this!

9. GEOLOGIC PRINCIPLES There are five major geologic principles: 1.Principle of Uniformitarianism 2.Principle of Lateral Continuity 3.Principle of Original Horizontality 4.Principle of Superposition 5.Principle of Cross-Cutting Relationships  These principles help geologists make predictions about sequences of events and thus the earth’s history.

10. PRINCIPLE OF UNIFORMITARIANISM This principle states that all the geological processes (Weathering, Erosion, Volcanism, Earthquakes, etc.) that occur today also occurred in the past in the same ways.

11. CHARLES LYELL “The present is the key to the past” Much of our knowledge of geologic materials, features, and past events is based on observation of currently active processes.

12. Lateral Continuity: original sedimentary layers extend laterally until it thins out at edges rocks that are otherwise similar, but are now separated by a valley or other erosional feature, can be assumed to be originally continuous.erosional

14. PRINCIPLES OF ORIGINAL HORIZONTALITY States that sediments are deposited in flat lying or horizontal layers that are parallel to the surface on which they were deposited. This means that if rocks are tilted or folded, they have been deformed after deposition.

15. IMPORTANT RELATIVE AGE DATING PRINCIPLES Original Horizontality: all beds originally deposited in water formed close to horizontal

17. PRINCIPLE OF SUPERPOSITION States that the rock layers on the bottom are oldest, the rock layers on the top are youngest. Unless the rock layers are overturned or folded Basically, if you pile a stack of papers, what ever paper was put down first, must be the oldest.

18. PRINCIPLE OF SUPERPOSITION OLDEST ROCK MIDDLE ROCK YOUNGEST ROCK

20. PRINCIPLE OF CROSS CUTTING RELATIONS States that if something (such as faults, cracks, veins, or intrusions - magma cooling underground, extrusions - lava cooling on the surface) cuts through rock layers, the rock layers themselves must be older than the thing cutting through them.

21. Cross-cutting Relationships: disruptions in any rock sequence occurred after the youngest established event in the undisturbed sequence Ie. A rock or fault is younger than any rock (or fault) through which it cuts

26. SEDIMENTARY DEPOSITION

28. INTRUSION

29. TILTING & EROSION

30. SUBSIDENCE AND NEW MARINE DEPOSITION

31. MISSING FORMATION

32. DIKE EVENT

33. EROSION AND EXPOSURE

34. SUBSIDENCE & DEPOSITION

35. FLUVIAL DEPOSITION

36. COMPLEX SUBSURFACE GEOLOGY

37. CONTACT RELATIONS