Leaving their Tradition Behind : Development of the Lami ...
The Data Joanne P. Ballard ([email protected]) & Professor … · 2009-05-08 · mulating...
1
F ire frequency during changing clima c condi ons yields insights into the ecological responses and adapta ons during mes of - spanning the Younger Dryas (12,900 – 11,600 cal yr BP) for east - central Michigan. Four lakes south of Flint, Michigan were sampled within a 10 mile radius range of each other. These lakes are situated in hummocky dri ſt terrain near the Saginaw lobe moraines. Swi ſt and Slack Lakes are on the northwest side of these moraines, so formed later and are therefore, younger than Big Fish and Lake Sixteen, which fall southeast of this geomorphological feature. All four lakes indicate high charcoal levels following deglacia on. There appears to be a consistent pa ern of elevated charcoal abun - dance amongst them. Stra graphically, the bo om peak in Swi ſt and Slack correlates chronologically to ~14,000 Cal BP. Big Fish and Lake Sixteen have older dates (15,160 Cal BP and 15,840 Cal BP re - spec vely). The earliest major peak in Big Fish begins an es mated ~1100 years later than the 15,160 Cal BP date. In Lake Sixteen there is a lesser double peak at the 15,840 Cal BP date which precedes the pa ern of spikes common to all lakes. The charcoal peaks follow the rise in organic content, and the accu - mula ng sediments vary from dark organic to lighter colored lami - Our preliminary es mate of dura on of these charcoal intervals in 12,200 14C (14,050 Cal BP) and con nue for about 1,500 years ( ll 12,550 BP). If so, these appear to occur in the cooling prior to the start of the Younger Dryas and they con nue un l the middle of the Younger Dryas, sugges ng that for these lakes the transi on between climate states is a controlling factor. 3. S TUDY L OCATION The Data Joanne P. Ballard ([email protected]) & Professor Thomas V. Lowell S UMMARY OF RESULT S 2. T HE S TUDY O BJECTIVES Aſter Marlon et al . 2009. Flint Swiſt Slack Lake Sixteen B i g F i s h Gainey sit e Gainey Paleo-Indian Tool Kit Image courtesy of Don Simons 1. ABSTRACT 6. THE DATA Joanne P Ballard 3-25-2009 12,200 14C yr ~14,050 Cal BP yr A7, 57 cm 8,050 14C yr ~9,000 Cal BP yr A5, 67-71 cm sediment-water interfac e 732 cm ~3050 years Swiſt Lake, Genesee County, Michigan Magnec suscepbility MS A1 MS A2 MS A3 MS A4 MS A5 MS A6 MS A7 MS A8 0 100 200 300 0 25 50 75 100 Organics Carbonate A7 0 200 400 600 800 1000 Charcoal count -coarse resoluon A7 A6 A4 A3 A2 A1 0 200 400 600 800 1000 A1 A2 A3 A4 Gamma Log Resisvity gm/cc 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 Depth in cm 2000 Loss on ignion 0 1 2 3 A1 A5 A2 A3 A4 A6 A7 A8 A5 A3 A4 A2 A1 A7 A6 A8 Joanne P Ballard 3-25-2009 12,050 14C ~13,900 Cal BP A4 51 cm 9,360 14C yrs ~10,580 Cal BP yrs A3 58-60 cm Loss on Ignion Magnec suscepbility SI units Charcoal count Slack Lake, Genesee County, Michigan Organics Carbonate 0 25 50 75 100 0 100 200 300 MS A1 MS A2 MS A3 MS A4 MS B1 MS B2 MS B3 MS B4 A2 A1 B4 B2 B1 B3 A4 A3 B4 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 Depth in cm 0 200 400 600 800 1000 -1 Gamma Log Density gm/cc 0 1 2 3 A1 B1 A2 A3 A4 B2 B3 B4 sediment-water interfac e 945 cm ~1800 Cal years 13,350 14C 15,840 Cal BP A1 21 cm A3 55 cm Joanne P Ballard 3-25-09 0 200 400 600 800 1000 0 100 200 300 MS A1 MS A2 MS A3 Magnetic Susceptibility Lake Sixteen, Oakland County, Michigan sediment-water interfac e 488 cm Loss on Ignion 0 25 50 75 100 Organics Carbonate A1 Organics A1 carbonate 850 900 950 1000 1050 1100 A3 A1 A2 Charcoal coarse methodology Charcoal Fine Methodology Dr. Cathy Whitlock’s Lab 11,150 14C years 13,080 Cal BP years 0 200 400 600 800 1000 - 1 0 1 2 3 A1 A2, A3 Gamma Log - Density 12,850 +/-55 14C yrs 15,160 Cal BP A2, 34-37 cm 10,300 14C yrs 12,075 Cal BP yrs B1 - 85 cm Big Fish Lake, Lapeer County, Michigan 0 200 400 600 800 1000 0 50 100 150 200 250 300 MS A1 MS A2 MS A3 MS A4 MS A5 MS B1 MS B2 MS B3 MS B4 A1 A3 A2 0 25 50 75 100 Organics Carbonates A3 Organics A3 Carbonate Loss on ignion Gamma Log Density gm/cc - 1 0 1 2 3 A1,A2 A3 A4 A5 B1,B2, B3, B4 B1 A5 A2 A3 A4 B4 Magnec suscepbility B3 B2 B1 0 200 400 600 800 1000 Charcoal count - Fine resoluon Charcoal count - Coarse r esoluon 900 950 1000 1050 1100 1150 1200 1250 1300 1350 Depth in cm sediment-water interfac e 945 cm Joanne P Ballard 3-25-2009 A5 B3 B2 Comet Lulin February 2009 Could a comet like this one have struck North America at the start of the Younger Dryas? 8. CONCLUSIONS 5. WORKING HYPOTHESES Extruding the lake sediment in Michigan for 12,900 years ago? " Analyzing lake sediments f or and later. Fire at 12,900 years ago does not manifest as more intense or lar ger to early Holocene. W hile it can be ar evidence to demonstrate an extraterrestrial source of ignion. Future wor k Pollen studies - vegetaon yields insight into paleoenvironmental/paleoclimate change Collect hist o data collected in this study. Expand study to a larger geographic region to determine if there is charcoal evidence of a contempor aneous Firestone, R.B., A. West, J.P. Kenne, L. Becker, T.E. Bunch, Z.S. Revay, P.H. Schultz, T. Belgya, D.J. Kenne, J.M. Erland- son, O.J. Dickenson, A.C. Goodyear, R.S. Harris, G.A. Howard, J. B. Kloosterman, P. Lechler, P.A. Mayewski, J. Mont- gomery, R. Poreda, T. Darrah, S.S. Que Hee, A.R. Smith, A Sch, W. Topping, J.H. Wike, and W.S. Wolbach. 2007. Evi- dence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal exncons and the Younger Dryas cooling. PNAS, October 9, 2007. Vol. 104, No. 41, pp. 16016-16021. Marlon, J. R., P. J. Bartlein, M. K. Walsh, S. P. Harrison, K. J. Brown, M. E. Edwards, P. E. Higuera, M. J. Power, R. S. Anderson, C. Briles, A. Brunelle, C. Carcaillet, M. Daniels, F. S. Hu, M. Lavoie, C. Long, T. Minckley, P. J. H. Richard, A. C. Sco, D. S. Shafer, W. Tinner, C. E. Umbanhowar, Jr., and C. W hitlock Proceedings of the Naonal Academy of the Sciences, January 2009 Early Edion. pp 1-6 www.pnas.org_cgi_doi_10.1073_pnas.0808212106 Whitlock, Cathy & Larsen, Chris “Charcoal as a Fire Proxy,” Chapter 5 in: Smol, John P., Birks, H. John B., Last, William M., Editors,Tracking Environmental Change Using Lake Sediments, pp. 75 - 97 Volume 3, Terrestrial, Algal and Siliceous Indicators. Springer Publisher: Kluwer Academic Publishers, 2001. GISP2 Ice Core Data hp://www.ncdc.noaa.gov/paleo/icecore/greenland/greenland.html hp://www.ncdc.noaa.gov/paleo/icecore/greenland/gisp/gisp.html Grootes, P,M,, and M, Stuiver, 1997, Oxygen 18/16 variability in Greenland snow and ice with 10^3 to 10^5-year me resoluon, Journal of Geophysical Research 102:26455-26470, NCDC NOAA World Data Center for Paleoclimatology Google Earth aerial images of lakes 4. O N I CE F EBRUARY 2008 " aspect of Firestone hypothesis " Target Gainey archaeological site (Firestone, et al, 2007) " Add 4 datasets for lateglacial pale o re record in the Midwest Coring crew at Slack Lake Jusn Stroup & Don Simons drilling depth-check hole at Swiſt Lake diat oms sapropel clay rich laminaons clay, black laminae diamict sand iron - limonite silt Najas seeds ostracode Big F ish 500 m Slack 400 m Sixt een 400 m Swi ſt 100 m Implicaons – We can predict some outcomes for the charcoal data. Hypothesis 1. Bolide strikes North America Hypothesis 2. Younger Dryas is arid Fire depends on at least 3 things to burn : *oxygen Graphs - Data is organized by depth in centimeters in all four lakes Magnetic susceptibility data is an indicaon of the presence of magnete parcles or a change in density. This can be seen downcore where the glacial gravel is present in all cores, and when a . Loss on Ignition is a test performed to assess what percentage or organics and carbonate are present in the lake sediment. Somemes these are in lock-step as seen in Lake Sixteen. Organics - there are other minerals present, such as silica or clays. Gamma log data are an indicaon of density High resolution photographs of the lake cores were taken at the world class Limnological Re - search Center at University of Minnesota’s campus. These show sedimentological changes which can oſten be tracked in the LOI or MS graphs. Stylized stratigraphic column. This shows the type of lithology and presence of organics such as Najas seeds, gastropods, diatoms, and ostracodes. Charcoal. Sediment samples were collected at depth intervals connuously along the length of the core, treated to disaggregate, and sieved. The sieved samples were exam - ined under a light microsocope at ~23X and all charcoal parcles were counted on a grid system. Vegetaon and organic materials were noted and included on the stylized stra - graphic column. Radiocarbon dates. Two dates were obtained on each lake for a total of 8 dates. 3 of these were obtained on bulk sediment (lower Lake Sixteen, Upper Lake Sixteen, Upper Big Fish) as no organic material was found at the desired stragraphic level. The lower Big Fish date is on Najas seeds, abundant in secons of Big Fish. The Upper Swiſt Lake date is primarily on Daphnia egg cases. The bulk samples, Najas seeds and Daphnia are consid - ered to be subject to the possibility of contaminaon with carbonate if it is a hard water lake, which will skew the dates older by perhaps 800 years. 7. TIMELINE UNCERT AINTIES in this meline so three are fairly robust. The older Swiſt and Slack dates are robust. Aquac samples may be problemac if they are in a hard water lake and contami nated with “dead” carbon from inorganic carbonates. Bulk sediments may, but not necessarily, be erroneous due to carbonates or coal in the environment. Calibraon. Some dates have less uncertainty that others (bell shaped curve). Calib has been used to analyze and calibrate the radiocarbon dates. Sedimentaon. The esmate for the Younger Dryas horizon in these four lakes is interpolated from 2 radiocarbon dates in each lake, assuming constant sedimentaon rate. Swiſt Lake Lake Sixteen 100 200 300 400 500 charcoal counts Timeline with charcoal levels, Michigan USA 0 100 200 300 400 50 0 0 100 200 300 400 50 0 0 100 200 300 400 500 Big Fish Lake Slack Lake Joanne P Ballard 3-27-2009 -44 -42 -40 -38 - 36 - 34 parts per mil d18O GISP2 ice core 0 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 Calibrated age, years more snow less snow 12,900 yr ~14,500 yr ~13,400 yr warmer/weer? cooler/drier? Hypothesis 1 Bolide strikes North America 100 200 300 400 500 predicted cha rcoal paerns Timeline with hypotheses modeled 0 100 200 300 400 50 0 0 100 200 300 400 500 Hypothesis 3 Hypothesis 2 Younger Dryas is arid Joanne P Ballard 3-31-2009 -44 -42 -40 -38 - 36 - 34 parts per mil d18O GISP2 ice core 0 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 Calibrated age, years more snow less snow 12,900 yr ~14,500 yr ~13,400 yr warmer/weer? cooler/drier? simulated charcoal counts Clovis 12,200 - ~13,000 or earlier Later Paleo-Indian stone tools Redstone Cumberland Point Plainview Goshen Suwanee-Simpson Folsom Gainey R EFERENCES Joanne Ballard would like to thank: The Limnological Research Center Department of Geology and Geophysics - University of Minnesota, Minneapolis Donald B. Simons, Gainey site invesgator John Siler, Slack Lake owner William Swiſt, Swiſt Lake owner Allen West, coauthor of Firestone et al. Cathy Whitlock, Montana State University Eric Grimm, Chair Botany, Illinois State Museum Thomas V. Lowell *Jusn S. Stroup * Mike Oestr eich The Department of Geology at the University of Cincinna " " " " " "
Transcript of The Data Joanne P. Ballard ([email protected]) & Professor … · 2009-05-08 · mulating...
Fire frequency during changing climatic conditions yields insights into the ecological responses and adaptations during times of
-
spanning the Younger Dryas (12,900 – 11,600 cal yr BP) for east -central Michigan.
Four lakes south of Flint, Michigan were sampled within a 10 mile radius range of each other. These lakes are situated in hummocky drift terrain near the Saginaw lobe moraines. Swift and Slack Lakes are on the northwest side of these moraines, so formed later and are therefore, younger than Big Fish and Lake Sixteen, which fall southeast of this geomorphological feature.
All four lakes indicate high charcoal levels following deglaciation. There appears to be a consistent pattern of elevated charcoal abun -dance amongst them. Stratigraphically, the bottom peak in Swift and Slack correlates chronologically to ~14,000 Cal BP. Big Fish and Lake Sixteen have older dates (15,160 Cal BP and 15,840 Cal BP re -spectively). The earliest major peak in Big Fish begins an estimated ~1100 years later than the 15,160 Cal BP date. In Lake Sixteen there is a lesser double peak at the 15,840 Cal BP date which precedes the pattern of spikes common to all lakes.
The charcoal peaks follow the rise in organic content, and the accu -mulating sediments vary from dark organic to lighter colored lami -
Our preliminary estimate of duration of these charcoal intervals in
12,200 14C (14,050 Cal BP) and continue for about 1,500 years (till 12,550 BP). If so, these appear to occur in the cooling prior to the start of the Younger Dryas and they continue until the middle of the Younger Dryas, suggesting that for these lakes the transition between climate states is a controlling factor.
3. STUDY LOCATION
The Data Joanne P. Ballard ([email protected]) & Professor Thomas V. Lowell
SUMMARY OF RESULTS
2. THE STUDY OBJECTIVES
After Marlon et al. 2009.
Flint
SwiftSlack
Lake Sixteen
Big Fish
Gainey site
Gainey Paleo-Indian Tool KitImage courtesy of Don Simons
1. ABSTRACT
References
6. THE DATA
Joanne P Ballard 3-25-2009
12,200 14C yr ~14,050 Cal BP yr A7, 57 cm
8,050 14C yr ~9,000 Cal BP yrA5, 67-71 cm
sediment-water interface732 cm
~3050 years
Swift Lake, Genesee County, Michigan
Magnetic susceptibility
MS A1
MS A2
MS A3
MS A4
MS A5
MS A6
MS A7
MS A8
0 100 200 3000 25 50 75 100
Organics
CarbonateA7
0 200 400 600 800 1000
Charcoal count -coarse resolution
A7
A6A4
A3
A2
A1
0 200 400 600 800 1000
A1
A2
A3
A4
Gamma Log Resistivity gm/cc
1400
1450
1500
1550
1600
1650
1700
1750
1800
1850
1900
1950
Dep
thin
cm
2000
Loss on ignition
0 1 2 3
A1
A5
A2
A3
A4
A6
A7
A8
A5A3
A4
A2
A1
A7
A6
A8
Joanne P Ballard 3-25-2009
12,050 14C
~13,900 Cal BP A4 51 cm
9,360 14C yrs
~10,580 Cal BP yrs A3 58-60 cm
Loss on IgnitionMagnetic susceptibility SI units Charcoal count
Slack Lake, Genesee County, Michigan
OrganicsCarbonate
0 25 50 75 1000 100 200 300
MS A1
MS A2
MS A3
MS A4
MS B1
MS B2
MS B3
MS B4
A2
A1
B4
B2
B1
B3
A4
A3
B4
1400
1450
1500
1550
1600
1650
1700
1750
1800
1850
Dep
th in
cm
0 200 400 600 800 1000-1
Gamma Log Density gm/cc
0 1 2 3
A1
B1
A2
A3
A4
B2
B3
B4
sediment-water interface945 cm
~1800 Cal years
13,350 14C
15,840 Cal BPA1 21 cm
A3 55 cm
Joanne P Ballard 3-25-09
0 200 400 600 800 10000 100 200 300
MS A1MS A2MS A3
Magnetic Susceptibility
Lake Sixteen, Oakland County, Michigansediment-water interface 488 cm
Loss on Ignition
0 25 50 75 100
Organics
Carbonate
A1 Organics
A1 carbonate
850
900
950
1000
1050
1100
A3
A1
A2
Charcoal coarse methodology
Charcoal Fine Methodology Dr. Cathy Whitlock’s Lab
11,150 14C years13,080 Cal BP years
0 200 400 600 800 1000-1 0 1 2 3
A1
A2, A3
Gamma Log - Density
12,850 +/-55 14C yrs15,160 Cal BP A2, 34-37 cm
10,300 14C yrs12,075 Cal BP yrsB1 - 85 cm
Big Fish Lake, Lapeer County, Michigan
0 200 400 600 800 10000 50 100 150 200 250 300
MS A1
MS A2
MS A3
MS A4
MS A5
MS B1
MS B2
MS B3
MS B4
A1
A3
A2
0 25 50 75 100
Org anics
Carbonates
A3 Org anics
A3 Carbonate
Loss on ignition Gamma Log Density gm/cc
- 1 0 1 2 3
A1, A2
A3
A4
A5
B1,B2, B3, B4
B1
A5
A2
A3
A4
B4
Magnetic susceptibility
B3
B2
B1
0 200 400 600 800 1000
Charcoal count - Fine resolutionCharcoal count - Coarse resolution
900
950
1000
1050
1100
1150
1200
1250
1300
1350
Dep
th in
cm
sediment-water interface945 cm
Joanne P Ballard 3-25-2009
A5
B3
B2
Comet Lulin February 2009 Could a comet like this one have struck North America at the start of the Younger Dryas?
8. CONCLUSIONS
5. WORKING HYPOTHESES
Extruding the lake sediment
in Michigan for 12,900 years ago? Analyzing lake sediments for
and later.Fire at 12,900 years ago does not manifest as more intense or larger
to early Holocene.While it can be ar
evidence to demonstrate an extraterrestrial source of ignition.
Future work
Pollen studies - vegetation yields insight into paleoenvironmental/paleoclimate change
Collect histo data collected in this study.
Expand study to a larger geographic region to determine if there is charcoal evidence of a contemporaneous
Firestone, R.B., A. West, J.P. Kennett, L. Becker, T.E. Bunch, Z.S. Revay, P.H. Schultz, T. Belgya, D.J. Kennett, J.M. Erland-son, O.J. Dickenson, A.C. Goodyear, R.S. Harris, G.A. Howard, J. B. Kloosterman, P. Lechler, P.A. Mayewski, J. Mont-gomery, R. Poreda, T. Darrah, S.S. Que Hee, A.R. Smith, A Stich, W. Topping, J.H. Wittke, and W.S. Wolbach. 2007. Evi-dence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. PNAS, October 9, 2007. Vol. 104, No. 41, pp. 16016-16021.
Marlon, J. R., P. J. Bartlein, M. K. Walsh, S. P. Harrison, K. J. Brown, M. E. Edwards, P. E. Higuera, M. J. Power, R. S. Anderson, C. Briles, A. Brunelle, C. Carcaillet, M. Daniels, F. S. Hu, M. Lavoie, C. Long, T. Minckley, P. J. H. Richard, A. C. Scott, D. S. Shafer, W. Tinner, C. E. Umbanhowar, Jr., and C. Whitlock
Proceedings of the National Academy of the Sciences, January 2009 Early Edition. pp 1-6www.pnas.org_cgi_doi_10.1073_pnas.0808212106
Whitlock, Cathy & Larsen, Chris “Charcoal as a Fire Proxy,” Chapter 5 in: Smol, John P., Birks, H. John B., Last, William M., Editors,Tracking Environmental Change Using Lake Sediments, pp. 75 - 97Volume 3, Terrestrial, Algal and Siliceous Indicators. Springer Publisher: Kluwer Academic Publishers, 2001.
GISP2 Ice Core Datahttp://www.ncdc.noaa.gov/paleo/icecore/greenland/greenland.htmlhttp://www.ncdc.noaa.gov/paleo/icecore/greenland/gisp/gisp.htmlGrootes, P,M,, and M, Stuiver, 1997, Oxygen 18/16 variability in Greenland snow and ice with 10^3 to 10^5-year time resolution, Journal of Geophysical Research 102:26455-26470, NCDC NOAA World Data Center for Paleoclimatology
Google Earth aerial images of lakes
4. ON ICE FEBRUARY 2008
aspect of Firestone hypothesis Target Gainey archaeological site (Firestone, et al, 2007) Add 4 datasets for lateglacial paleo re recordin the Midwest
Coring crew at Slack Lake Justin Stroup & Don Simons drilling depth-check hole at Swift Lake
diatoms
sapropel
clay rich laminations clay, black laminae
diamict sand
iron - limonite
silt
Najas seeds
ostracode
Big Fish
500 m
Slack
400 m
Sixteen
400 m
Swift100 m
Implications – We can predict some outcomes for the charcoal data.Hypothesis 1. Bolide strikes North AmericaHypothesis 2. Younger Dryas is arid
Fire depends on at least 3 things to burn:*oxygen
Graphs - Data is organized by depth in centimeters in all four lakesMagnetic susceptibility data is an indication of the presence of magnetite particles or a change in density. This can be seen downcore where the glacial gravel is present in all cores, and when a
.
Loss on Ignition is a test performed to assess what percentage or organics and carbonate are present in the lake sediment. Sometimes these are in lock-step as seen in Lake Sixteen. Organics
-
there are other minerals present, such as silica or clays.
Gamma log data are an indication of density
High resolution photographs of the lake cores were taken at the world class Limnological Re -search Center at University of Minnesota’s campus. These show sedimentological changes which can often be tracked in the LOI or MS graphs.
Stylized stratigraphic column. This shows the type of lithology and presence of organics such as Najas seeds, gastropods, diatoms, and ostracodes.
Charcoal. Sediment samples were collected at depth intervals continuously along the length of the core, treated to disaggregate, and sieved. The sieved samples were exam -ined under a light microsocope at ~23X and all charcoal particles were counted on a grid system. Vegetation and organic materials were noted and included on the stylized strati -graphic column.
Radiocarbon dates. Two dates were obtained on each lake for a total of 8 dates. 3 of these were obtained on bulk sediment (lower Lake Sixteen, Upper Lake Sixteen, Upper Big Fish) as no organic material was found at the desired stratigraphic level. The lower Big Fish date is on Najas seeds, abundant in sections of Big Fish. The Upper Swift Lake date is primarily on Daphnia egg cases. The bulk samples, Najas seeds and Daphnia are consid -ered to be subject to the possibility of contamination with carbonate if it is a hard water lake, which will skew the dates older by perhaps 800 years.
7. TIMELINE
UNCERTAINTIES in this timeline
so three are fairly robust. The older Swift and Slack dates are robust. Aquatic samples may be problematic if they are in a hard water lake and contami nated with “dead” carbon from inorganic carbonates. Bulk sediments may, but not necessarily, be erroneous due to carbonates or coal in the environment.
Calibration. Some dates have less uncertainty that others (bell shaped curve). Calib has been used to analyze and calibrate the radiocarbon dates.
Sedimentation. The estimate for the Younger Dryas horizon in these four lakes is interpolated from 2 radiocarbon dates in each lake, assuming constant sedimentation rate.
Swift Lake Lake Sixteen
100 200 300 400 500
charcoal counts
Timeline with charcoal levels, Michigan USA
0 100 200 300 400 500 0 100 200 300 400 500 0 100 200 300 400 500
Big Fish LakeSlack Lake
Joanne P Ballard 3-27-2009
- 44- 42- 40-38- 36-34
parts per mil
d18O GISP2 ice core
0
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
Cal
ibra
ted
age,
yea
rs
more snow less snow
12,900 yr
~14,500 yr
~13,400 yr
warmer/wetter? cooler/drier?
Hypothesis 1Bolide strikesNorth America
100 200 300 400 500
predicted cha rcoal patterns
Timeline with hypotheses modeled
0 100 200 300 400 500 0 100 200 300 400 500
Hypothesis 3Hypothesis 2YoungerDryas is arid
Joanne P Ballard 3-31-2009
- 44
- 42- 40-38- 36-34
parts per mil
d18O GISP2 ice core
0
8000
9000
10000
11000
12000
13000
14000
15000
16000
17000
18000
Cal
ibra
ted
age,
yea
rs
more snow less snow
12,900 yr
~14,500 yr
~13,400 yr
warmer/wetter? cooler/drier?
simulated charcoal counts
Clovis 12,200 - ~13,000 or earlier
Later Paleo-Indian stone toolsRedstoneCumberland PointPlainview GoshenSuwanee-SimpsonFolsomGainey
REFERENCES
Joanne Ballard would like to thank:The Limnological Research CenterDepartment of Geology and Geophysics - University of Minnesota, Minneapolis
Donald B. Simons, Gainey site investigatorJohn Siler, Slack Lake ownerWilliam Swift, Swift Lake ownerAllen West, coauthor of Firestone et al.Cathy Whitlock, Montana State UniversityEric Grimm, Chair Botany, Illinois State MuseumThomas V. Lowell *Justin S. Stroup * Mike Oestreich
The Department of Geology at the University of Cincinnati
![Ako nespáliť server - Monit [Jozef Lami] (7. sraz, Praha)](https://static.fdocuments.net/doc/165x107/58728af91a28ab36118b50e7/ako-nespalit-server-monit-jozef-lami-7-sraz-praha.jpg)
