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Unformatted text preview: Scientific Method The scientific method- a research strategy based on the principle that every physical event has a physical explanation Data interpretation and hypothesis construction- tentative explanation based on data collected through observation and experimentation. With a hypothesis you can predict. Theory- a hypothesis that has survived repeated challenges and experiments Data collecting - Hypothesis constructing - n x Hypothesis testing Theory Hypothesis testing never stops, and even well established hypotheses need to be tested against new data. Uniformitarianism- Interpretation of historical data based on present- day geological phenomena James Hutton- Father of Geology The Theory of the Earth (1785) Charles Lyell- Geologist Principles of Geology The past history of our globe must be explained by what can be seen to be happening now The present is the key to the past Methodological o Uniformity of Law: Foundation of historical science. Ex: Gravity o Uniformity of Process: Actualism. Ex: Water Cycle. Not Valid Substantive o Uniformity of Rate and magnitude: Gradualism (Things do change, but at constant rate). Not Valid o Uniformity of Condition: nondirectionism (Things dont change; or the Earth system has been maintaining the same quilibrium state). Not Valid Catastrophism Found by Curvier and Brongniart Studied fossils in the Paris Basin Used the Bibles Noahs Arc story to hypothesize about the rocks and fossils found in the Paris Basin Dramatic changes in successive fossil assemblages Believed that these changes were caued by total extinction resulted from catastrophes akin to the Noachian Deluge, followed by successive creations of new species We now know that these abrupt changes are largely due to unconformities or missing record Catastrophism has not been totally abandoned; it is particularly instructive in later studies on mass extinctions Stenos Principles Rocks deposited in the ocean (sedimentary rocks) form layers (strata) and follow the following principles: o The principle of original horizontality o The principle of original lateral continuity o The principle of superposition0 important for relative dating. Why some strata are not horizontal, contra Stenos first principle? Huttons unconformity with basal puddlingstone, or conglomerate, along the River Jed, Scotland. Some rock layers are vertical mostly because of earthquakes, lava, tectonic events, etc. o These rocks are then pushed above sea level. Then pushed down below sea level to make room for rocks above it Time Missing: Anglar Unconformity Unconformity: A substantial break or gap in the geologic record: o Angular Unocnformtiy: An unconformity between two groups of rocks whose bedding planes are not parallel: (older rocks tilted and eroded) o Parallel Unconformity: An unconformity between two group sof rocks...
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- Fall '08