Drift Precursors Drift as case study of scientific

Drift Precursors

Drift as case study of scientific method (& scientific ‘revolution’) Insights: (1) Science isn’t the ‘truth’, it’s a process for convincing others of the best answer to a question. (Corollary: too much introductory ‘science’ in school is spent memorizing ‘how the world is’ and not seeing that science is a process of rational inquiry) (2) The importance of data/observations in a paper. To convince specialists, papers must contain convincing data. (3) When a concept becomes accepted as a basic theory (‘law’), then the concept only is taught in order to more quickly digest/encapsulate the facts. (theories are taught as ‘truth’, but a duel between theoretical concepts is not what convinces practitioners) (4) Wegener rightly gets lion’s share of credit because he marshalled and digested a great deal of observations to support his insight (5) however, new observations led to the acceptance of drift…

03_05. jpg

03_00. jpg

Gondwana Landbridges

03_01. jpg

Isostasy – Contradicts Oceanic Landbridges Felsic cont. crust (Sial) Basaltic ocean crust (Sima) Continental crust ‘floats’ — can’t just rise and sink 5 km at will…

But Also Contradicts Geosynclines… (isostasy was not fully accepted until 1960 s)

03_02. jpg

03_03 a. jpg

03_03 b. jpg

03_04. jpg

03_05. jpg

03_06. jpg

Holmes Europe-NAm Mountain Fit

‘Flaw’ with Wegener’s drift — no plausible mechanism

Criticism: 1928 Drift Conference…

Holmes 1928: Modern Mechanism (Convection)

Holmes 1928: Modern Mechanism (Convection) 2

Holmes 1928: oops

03_07. jpg

03_08. jpg

03_09. jpg

03_10. jpg

03_11. jpg

03_12. jpg

03_13. jpg

03_14. jpg

03_15. jpg

03_16. jpg

03_17. jpg

03_18. jpg

03_19. jpg

03_20. jpg

03_21. jpg

03_22. jpg

03_23. jpg

Sea Floor Spreading This animation shows progressive stages in the opening of the Atlantic Ocean. The youngest rocks (in red) clearly outline the mid-ocean ridge system, complete with transform faults. The oldest ocean crust (in blue), is confined to offshore regions adjacent to the United States, Canada and western Africa. This distribution demonstrates that the North Atlantic began to open before the South Atlantic. PC version Mac version

03_24. jpg

03_25. jpg

03_26. jpg

Magnetic Reversals The polarity of Earth's magnetic field reverses with time. The main figure demonstrates how sea-floor anomalies, also known as magnetic stripes, develop during sea-floor spreading. The inset image records the reversal of Earth's dipole. PC version Mac version

03_27. jpg

03_28. jpg

03_29. jpg

Zoomable Art PC Mac 03_Featured_Art. jpg

03_30. jpg