Presentation on theme: "Siccar Point, Scotland The unconformable contact of Old Red Sandstone on vertical Silurian rocks noted by James Hutton, who in 1788 first recognized the."— Presentation transcript:
1Siccar Point, ScotlandThe unconformable contact of Old Red Sandstone on vertical Silurian rocks noted by James Hutton, who in 1788 first recognized the significance of its meaning in relationship to necessity for an old age for the earth“No vestige of a beginning, no prospect of an end.”
2Earth StructureEarth starts as molten ball of rock. Elements begin to differentiate (layers based on density).
3Earth StructureHow do we know its structure? -- deepest drill only 7 miles deep. -- infer from earthquakes (seismic activity). We use P-waves and S-waves.
4Seismic Waves Seismic = earthquakes P-wave: (pump) - fastest - travel completely through Earth.S-wave: (snake)- slow- no liquids- cause most damage
12Plate Tectonics Alfred Wegener - 1915 (Continental Drift) Evidence: -- Continents fit like a jigsaw puzzle.-- Same geology on each side of ocean. ex. Appalachian mountains, coal beds-- fossils of identical land animals on each side of ocean.