Denniston et al. 1999 north-central USA Speleothem Stable Isotope Data Denniston, R.F.; González, L.A.; Baker, R.G.; Asmerom, Y.; Reagan, M.K.; Edwards, R.L.; Alexander, E.C. Denniston, R.F. González, L.A. Baker, R.G. Asmerom, Y. Reagan, M.K. Edwards, R.L. Alexander, E.C. earth science/paleoclimate/speleothems (age,null,null,calendar year before present,null,speleothems,null,null,N,null) earth science/paleoclimate/speleothems (delta 13C,calcium carbonate,null,per mil PDB,null,speleothems,raw,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/speleothems (delta 18O,calcium carbonate,null,per mil SMOW,null,speleothems,raw,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/speleothems earth science/paleoclimate/speleothems (Spring Valley Caverns>LATITUDE 43.75>LONGITUDE -92.41) (Mystery Cave>LATITUDE 43.62>LONGITUDE -92.3) (Crystal Cave WI>LATITUDE 44.83>LONGITUDE -92.25) Carbon and oxygen isotopic trends from seven Midwestern speleothems record significant offsets in the timing of middle-Holocene vegetation change. Interactions of dry Pacific and moist Gulf of Mexico air masses maintained a sharp moisture gradient across Iowa, Minnesota, and Wisconsin such that the arrival of prairie was offset by 2000 years between caves and pollen sites located only 50 km apart. Oxygen isotopes shift concomitantly with carbon in most cases, although these changes are believed to represent increased evaporative enrichment of 18O prior to infiltration during the prairie period. STUDY NOTES: Stalagmites dated by U-Th Series, and isotope data collected on a Finnigan MAT 252 using a Kiel II device. ! Analyses of Cold Water Cave stalagmite 1S are tabuluated in Dorale et al. (1992). * The total length of SV-1 = 635 mm; SV-2 = 560 mm; MC-28 = 317 mm; CC-A = 311 mm. §d234Umeasured = [(234U/238U)measured/(234U/238U)eq –1] × 103, where (234U/238U)eq is the secular equilibrium atomic ratio: lamda238/lamda234 = 5.472 × 10- 5. Values in parentheses are 2sigma uncertainties. † Ages are relative to the time of measurement, 1994–1996. Ages are calculated using a modification of the standard age equations (Broecker and Thurber,1965) modified to correct for initial 230Th assuming an initial 230Th/232Th ratio of 4.4 × 10- 6(± 2.2 × 10- 6). Half lives are those used in Edwards et al. (1987). Although analytically precise, uncertainty associated with drilling large (~1 g) samples increases the effective error of these dates. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Denniston, R.F. Investigator : González, L.A. Investigator : Baker, R.G. Investigator : Asmerom, Y. Investigator : Reagan, M.K. Investigator : Edwards, R.L. Investigator : Alexander, E.C. 1999-01-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/5428 https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/minnesota/mystery_cave.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/minnesota/spring_valley_caverns.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/wisconsin/crystal_cave.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/minnesota/mystery_cave.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/minnesota/spring_valley_caverns.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/wisconsin/crystal_cave.txt English https://www.ncdc.noaa.gov/paleo/study/5428 https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/minnesota/mystery_cave.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/minnesota/spring_valley_caverns.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/usa/wisconsin/crystal_cave.txt Denniston, R.F., L.A. González, R.G. Baker, Y. Asmerom, M.K. Reagan, R.L. Edwards, and C. Alexander1999Speleothem evidence for Holocene fluctuations of the prairie-forest ecotone, north-central USAThe Holocene96671-67610.1191/095968399674716399 START YEAR: -6567 AD * END YEAR: 1950 AD -92.41 43.62 -92.25 44.83