GEOL 1001 Lecture : August 24th Notes
Document Summary
Some geologic events are slow: it took more than 250 million years to deposit this sequence of rocks in the grand canyon, the rocks at the bottom of the canyon are about 2 billion years old. Some geologic events are rapid: meteor crater, this feature (2 km across) formed in less than one minute. Some geologic investigation are microscopic about 50,000 years ago: features less than 0. 1 mm can give important info about the history of many rocks. Seismic waves- illuminate earths interior: compression and shear waves behave differently and are bent or absorbed at layer (chemical) boundaries within the earth. Earths interior is layered according to density: surface rock density is less than 3. 5 g/cm^3, whole earth density is 5. 5 g/cm^3, core density must be about 8 g/cm^3. Composition of the earth (70%: key earth elements in the crust: o, si, key earth elements in the earth: fe, o, si, mg.
