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

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

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

How Dendrogeomorphology Any unusual change in ring growth –Decreased/increased width growth –Decreased/increased ring wood density

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

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

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

What Dendrogeomorphology Earthquakes: 1989 Loma Prieta

What Dendrogeomorphology Earthquakes Volcanic eruptions

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

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

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

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

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

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

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?

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

Dendrogeomorphology Quadruple Junction 1.Geomorphic process, frequent and recent 2.Must damage trees without destroying evidence 3.Must be old trees, with crossdating 4.Compelling hazard to humans

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

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

Dendroseismology: Southern California 1.Recent event (1857), previous event thought to be within 200 years 2.Living trees show 1857 event 3.Long-lived pines and firs 4.Millions of people living nearby, some right on the San Andreas

Pool Tree Huge Jeffrey No top Sag pond pool

Lone Pine Canyon Huge Jeffrey No top Right on fault

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

60 km south of Wrightwood Big earthquake in 1812, Dec. 8. San Juan Capistrano

Short segment ruptured, but longer than our trees The word “irregular” made it in title – yrs – yrs –2003 Interpretation

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?

Dendrovolcanism: Sunset Crater 1.Last event not very recent (AD 1064?) 2.Trees from archeo collections show that event 3.Crossdating legendary 4.Sinaguans lived nearby 5.Calibration from Parícutin 1940s?

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?

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

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?

Interpretation (so far) Clear visible effects on this tree P and Ca response might be indirect  soil pH changes Either way, a useful chemical variable Will this show up in Sunset Crater archeo wood collection? Could refine start date of eruption Could better define length of eruption