Dendrochronology Workshop

1

• Dendrochronology Workshop
• Geos. 497C/597C
• Crosslisted
• Dendrochronology building
• Measurement of ring widths
• Date checking (COFECHA)
• Detrending
• Chronology evaluation
• Org. meeting Jan. 10, 100 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
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
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

• Earthquakes
• Volcanic eruptions

• Aeolian
• Great L. dunes

• Other ground
• Mud/debris flow, rockfall
• Soil creep
• Water
• Shoreline
• Riverine

13
What Dendrogeomorphology

• Earthquakes
• Volcanic eruptions

• Aeolian
• Great L. dunes

• 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

15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
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

22
(No Transcript)
23
DendrogeomorphologyQuadruple 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

24
Dendovolcanics Mount St. Helens

• A virtual dendrogeomorph playground
• Recent eruptions
• Lots of old trees
• Lots of people

25
(No Transcript)
26
1842
1843
1845
27
(No Transcript)
28
(No Transcript)
29
(No Transcript)
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
DendroseismologySouthern 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

32
(No Transcript)
33
(No Transcript)
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.

38
(No Transcript)
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
DendrovolcanismSunset 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?

42
(No Transcript)
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

45
(No Transcript)
46
(No Transcript)
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?

48
(No Transcript)
49
(No Transcript)
50
(No Transcript)
51

• 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