The Geographic Cycle

1. The Geographic Cycle WM Davis

2. William Morris Davis • Born February 12, 1850, Philadelphia, PA • -Graduated from Harvard 1869 • -Instructor of geology at Harvard, 1879 • (never finished his Ph.D.) • -In addition to work on physical geography, • Davis was very involved in educational • theory and professional association (founded • the Association of American Geographers, 1904) • -Died February 5, 1934, Pasadena, CA • Source: http://www.wikipedia.org

3. HistoricalContext • Developmentofgeologyas a separatebranchofscience-1775 to1830. • Hutton(1726-1797) -uniformitarinism. JohnPlayfair(1748-1819) publicisedHutton'stheoriesandaddedfurtherideas. • Lyellpublishedtheclassictextbook, 'PrinciplesofGeology', in 1830-1833. • WilliamSmith(1769-1839)-stratigraphicalsuccessionsbasedonfossils • BythemiddleoftheNineteenthCentury, thegeneralgeologicaltimescalebasedonfossilsandstratigraphicmappingwasestablished. • GeomorphologicalstudieswereadvancedbytheworkofAgassiz, whointhe 1840s recognisedtheeffectsofPleistoceneglaciationinEuropeandthe USA. • LaterGilbertandPowellmadeclassicalstudiesonariderosioninthewestern USA. • Thestrongestinfluenceupto 1900 wastheworkofW.H. Davis, anAmericanwhoworkedbothin USA andEuropeandwhofirstdefinedthecycleoferosion. James Hutton by Abner Lowe Information provided by: http://www.minerals.nsw.gov.au

4. Landscapeis a FunctionoftheseGeographicalControls • Structure • Horizontal (plains, etc.) • Disordered (mountains, etc.) • Process • Time

5. W. M. Davis W. M. Davis W. M. Davis The Landscape The Landscape The Landscape Davisian Analysis Rejuvenation uplift base level fall relief increase; then, decrease “Youth” “Maturity” “Old Age”

6. In the 1960s and 1970s, Henry Besairie mapped much of the central plateau of Madagascar as dissected peneplain…discuss! (Google Earth)

7. Facts of Observation (pg. 484) • The explorer of the Earth should be as fully convinced of this principle (that geolographical landforms have meaning), and as well prepared to apply it, as the explorer of the sky is to carry physical principles to the furthest reach of his telescope, his spectro- scope, and his camera. The preparation of route-maps ……is only the beginning of exploration, which has no end till all the facts of observation are carried forward to explanation.

8. ChallengesGeographerstobecome “Wasteformologists” • “As a consequence, the scheme gains a very " theoretical" flavour that is not relished by some geographers, whose work implies that geography, unlike all other sciences, should be developed by the use of only certain ones of the mental faculties, chiefly observation, description, and generalization.” (483)

9. “Systematic Investigation of Land-forms”(pg. 498) • Itsvaluetothegeographerisnotsimplyingivingexplanationtoland- forms; itsgreatervalueisinenablinghimtoseewhathelooksat, andtosaywhathesees. • …Significantfeaturesareconsciouslysoughtfor; explorationbecomesmoresystematicandlesshaphazard….."A hillyregion" bringsnodefinitepicturebeforethementaleyes. "A maturelydissectedupland" suggests a systematicassociationofwell-definedfeatures;….

10. Discussion Points • “So with waste-sheets; they normally begin to establish a graded condition at their base, and then extend it up the slope of the valley side whose waste they ‘drain’.” (pg. 496) • Rills on hillslopes also graded in old age? (489) • Stream terminology – “consequent”, “insequent”, etc. (pg 490-493) • Figure 1?

11. Romans? • “Tolookupon a landscapeofthiskindwithoutanyrecognitionofthelabourexpendedinproducingit, oroftheextraordinaryadjustmentsofstreamstostructures, andofwastetoweather, islikevisitingRomeintheignorantbeliefthattheRomansofto-dayhavehadnoancestors. “