8/26/14 Chapter 1: Time and Change ● Krakatoa 1883 ○ explosion heard 3000 miles away ○ wind blown ash for 3 years ○ first natural disaster known instantly by telegraph, submarine cable ● Thera 3500 BC ○ Collapse ● San Francisco earthquake 1906 ● Sumatra tsunami 2006 ● Vesuvius eruption AD 76 ● Volcanic eruptions: average 20/year ● Major earthquake: average 150/year ● Small tremors: 800,000/year = 1every 40 seconds ● 2001: Tropical Storm Allison ○ 100 year flood > 200 year flood ○ 10,000 times in 1,000,000 years ● Katrina, Rita 2005 ● During Ice Age: sea level fell 100 m to shelf edge ● Post glacial warming: ice melted, climate zones migrated ● Fertile Crecent, Nile Delta: Agrarian civilizations developed with irrigations ● TigrisEuphrates delta ○ marine regression ○ Iraq is a delta ○ The river delivers more sediment than the water can remove so a delta is formed ● Scandinavian crust is rising because it was covered in ice. Rising back (isostatic rebound) ○ local sea level is falling ○ baltic sea won’t exist ● Catastrophism: sudden, violent events produce important changes; earth is young ~ 6000 years ● Uniformitarianism: everyday processes produce incremental, cumulative change; earth is very old ● Dynamic Equilibrium: momentary balance of opposing processes; may be long lived or frequently disturbed and re set ● Evolution: longterm, directional change Chapter 2: Beginning of Earth Science ● Before 1800 most europeans assumed was very young ● What is Science? ○ Scientia, wisdom ○ way of reasoning, observing and testing ○ first to seek natural principles to explain processes (Aristotle) ■ Foundation of modern scientific worldview ○ the universe operates according to natural laws> the universe runs itself and follows those laws > unmans can understand those laws ● Hypothesis ○ an explanation of: ■ nature and origin of a thing ■ cause of a phenomenon ■ how a process ought to work ○ can be rejected (nullified, disposed) ○ must have multiple hypothesis ○ can be modified, improved, expanded, upgraded ○ can never be “proved” ● Theory ○ a well supported, much tested hypothesis ○ proof is not possible in science, only probability ■ all theories are provisional, not permenant ● What is a fossil? ○ organic; yes, no, sortof ● Organic Theory ○ a fossil is any evidence for preexisting life, of any age ■ shells, bones, teeth, tracks, trails, burrows ○ Greek naturalists 500 BC ■ observed seashells in limestone in mountains of Greece ○ Leonardo da Vinci 1500 ■ fragile marine shells preserved in place, not transported ■ fossil assemblages resemble living species communities ■ fossils result from multiple events and processes ■ not relicts of the Deluge ● Robert Hooke 1703 ○ Principle of Functional Anatomy: explains form by function; fossils should be interpreted by same biological principles as living animals ○ some (most) fossils are extinct! ■ was Creation imperfect? ■ Can fossils be used to date strata? ● Nicholaus Steno 1669 ○ Danish physician ○ 1669 First Geological Treatise ■ “Introduction to a dissertation on the solid substance naturally contained within solids” ■ first to explain important geological relationships ■ fossils accumulated along with rocks layer by layer ■ details of each layer reflect local conditions, processes ● Stratification ○ sedimentary rocks are layered ■ gravitational field ■ new layer above existing ones ○ Steno’s Laws are the basis for Stratigraphy: ■ Science of interpreting stratified rocks ● Principle of Original horizontality ● Principle of Original Lateral Continuity ● Principle of Superposition ○ simple but powerful rule: allows relative dating of stratified rocks and the fossil assemblage they contain ● Principle of CrossCutting relationships ○ structures: folds, faults, stratification ○ Steno applied to it deformational events ○ James Hutton added intrusive igneous metamorphic events ○ the intrusion is younger ● Law of included fragments ○ fragments enclosed within another rock must be older ○