Dendrogeomorphology Workshop: Tree-Ring Science in Surficial Geology

1. Dendrochronology Workshop • Geos. 497C/597C • Crosslisted • Dendrochronology building • Measurement of ring widths • Date checking (COFECHA) • Detrending • Chronology evaluation • Org. meeting: Jan. 10, 1:00 M, here

2. Dendrogeomorphology (Dendrochronogeomorphology) Tree-Ring Science Applied to Recent Surficial Geology Paul R. Sheppard LTRR, UA

3. Background lecture • Various examples • Web images • Old business: • Dating, discovering previously unknown earthquake on southern San Andreas • New business: • Current research on Sunset/Parícutin

4. How Dendrogeomorphology • Any unusual change in ring growth • Decreased/increased width growth • Decreased/increased ring wood density

5. Hebgen Lake, 1959 How Dendrogeomorphology • Any unusual change in ring growth • Decreased/increased width growth • Decreased/increased ring wood density • Death/initiation date

6. How Dendrogeomorphology • Any unusual change in ring growth • Decreased/increased width growth • Decreased/increased ring wood density • Death/initiation date

7. Hebgen Lake, 1959 How Dendrogeomorphology • Any unusual change in ring growth • Decreased/increased width growth • Decreased/increased ring wood density • Death/initiation date • Reaction wood/abrasion scar

8. How Dendrogeomorphology • Any unusual change in ring growth • Decreased/increased width growth • Decreased/increased ring wood density • Death/initiation date • Reaction wood/abrasion scar • Ring chemical changes • Nitrogen? • Strontium?

9. What Dendrogeomorphology • Earthquakes: 1989 Loma Prieta

10. What Dendrogeomorphology • Earthquakes • Volcanic eruptions

11. What Dendrogeomorphology • Earthquakes • Volcanic eruptions • Other ground • Mud/debris flow, rockfall • Soil creep • Water • Shoreline • Riverine

12. What Dendrogeomorphology • Aeolian • Great L. dunes • Earthquakes • Volcanic eruptions • Other ground • Mud/debris flow, rockfall • Soil creep • Water • Shoreline • Riverine

13. What Dendrogeomorphology • Aeolian • Great L. dunes • Earthquakes • Volcanic eruptions • Snow • Neo advances • Avalanches (Dexter) • Permafrost • Ice ramparts, jams • Other ground • Mud/debris flow, rockfall • Soil creep • Water • Shoreline • Riverine

14. Why Dendrogeomorphology • Basic understanding of surficial processes • Dates, therefore frequency of events • Location, areal extent • Magnitude • Temporal-spatial coherence • E.g., volcanism related to seismicity? • Medicine Lake Highlands

18. Why Dendrogeomorphology • Basic understanding of surficial processes • Dates, therefore frequency of events • Location • Magnitude • Temporal-spatial coherence • E.g., volcanism related to seismicity? • Medicine Lake Highlands • Future prediction not a goal so much

19. Dendrogeomorphology Fundamentals • Uniformitarianism • Events affect trees similarly • Absolute conditions need not be similar • Limiting factors • Events change what limits tree growth • Site selection • Certainly not random • Carefully considered

20. Dendrogeomorphology Fundamentals • Crossdating • Annual precision a strength of dendro • Getting “close” could be misleading • Sensitivity • Enough to facilitate crossdating • Not too much, mimic geomorphic signal • Replication • How many trees with geomorphic signal?

21. Dendrogeomorphology Fundamentals • Control (expectation) • Growth prior to event • Growth of other trees after event • Departure from expectation • Also caused by climate, ecological events • Mapping often critical • Calibration to known event would be nice • Vanishing evidence

23. DendrogeomorphologyQuadruple Junction • Geomorphic process, frequent and recent • Must damage trees without destroying evidence • Must be old trees, with crossdating • Compelling hazard to humans

24. Dendovolcanics Mount St. Helens • A virtual dendrogeomorph playground • Recent eruptions • Lots of old trees • Lots of people

26. 1842 1843 1845

30. Interpretation • 1842 event trees were in lahar surge • Formation of Goat Rocks Dome began shortly (within 10 years) before that • Petrologic cycle of dacite-andesite-dacite

31. Dendroseismology:Southern California • Recent event (1857), previous event thought to be within 200 years • Living trees show 1857 event • Long-lived pines and firs • Millions of people living nearby, some right on the San Andreas

34. Pool Tree • Huge Jeffrey • No top • Sag pond pool

35. Lone Pine Canyon • Huge Jeffrey • No top • Right on fault

36. All Trees • Control chronology robust • 1812 & 1857 drought years? • Nine event trees • Pines, firs • Confirm 1857, show 1812 • Span 12 km of fault

37. San JuanCapistrano • 60 km south of Wrightwood • Big earthquake in 1812, Dec. 8.

39. Interpretation • Short segment ruptured, but longer than our trees • The word “irregular” made it in title • 1812 45 yrs • 1857 146 yrs • 2003

40. Another Interpretation • Seismic ruptures displace stress, rather than eliminate it (SciAm, Jan. 2003) • Stress displaced to the north? • 1812 southern California 45 yrs • 1857 central California 49 yrs • 1906 San Francisco • When will south start again?

41. Dendrovolcanism:Sunset Crater • Last event not very recent (AD 1064?) • Trees from archeo collections show that event • Crossdating legendary • Sinaguans lived nearby • Calibration from Parícutin 1940s?

43. Questions About Sunset • Nature of association of event trees with eruption? • Eruption perhaps a lengthy event? • Did ash truly improve environmental conditions for Sinagua? • “Blank Sand,” by Colton?

44. Parícutin, Mexico • Cinder cone, similar to Sunset • Well known modern event • 1940s-50s eruption • Lava, ash fall well-mapped • Forested area, then and now • Perhaps could serve as a calibration for Sunset

47. Parícutin • Last January • Big, young pines • Most start in 1960s • A few start in 1930s • Some old stumps • Dating not great, hopefully passable • Will measure widths and elements • Nitrogen?