GISP2 Ice Core Stratigraphy Alley, R.B.; Shuman, C.A.; Meese, D.A.; Gow, A.J.; Taylor, K.C.; Cuffey, K.M.; Fitzpatrick, J.J.; Grootes, P.M.; Zielinski, G.A.; Ram, M.; Spinelli, G.; Elder, B. Alley, R.B. Shuman, C.A. Meese, D.A. Gow, A.J. Taylor, K.C. Cuffey, K.M. Fitzpatrick, J.J. Grootes, P.M. Zielinski, G.A. Ram, M. Spinelli, G. Elder, B. earth science/paleoclimate/ice cores (ice age,null,null,year Common Era,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (notes,null,null,null,null,ice cores,null,null,N,accumulation rate/layer thickness) earth science/paleoclimate/ice cores (depth,null,null,meter,null,ice cores,null,null,N,based on ECM) earth science/paleoclimate/ice cores (depth,null,null,meter,null,ice cores,null,null,N,based on visual strat) earth science/paleoclimate/ice cores (layer thickness,bulk ice,null,meter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (ice age,null,null,calendar year before present,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (density,bulk ice,null,gram per cubic centimeter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (notes,null,null,null,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (accumulation rate,bulk ice,null,meter per year,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (depth,null,null,meter,null,ice cores,null,null,N,null) earth science/paleoclimate/ice cores (layer thickness,bulk ice,null,meter,null,ice cores,null,null,N,water equivalent) earth science/paleoclimate/ice core (GISP2>LATITUDE 72.6>LONGITUDE -38.5) Annual layers are visible in the Greenland Ice Sheet Project 2 ice core from central Greenland, allowing rapid dating of the core. Changes in bubble and grain structure caused by near-surface, primarily summertime formation of hoar complexes provide the main visible annual marker in the Holocene, and changes in "cloudiness" of the ice correlated with dustiness mark Wisconsinan annual cycles; both markers are evident and have been intercalibrated in early Holocene ice. Layer counts are reproducible between different workers and for one worker at different times, with 1% error over century-length times in the Holocene. Reproducibility is typically 5% in Wisconsinan ice-age ice and decreases with increasing age and depth. Cumulative ages from visible stratigraphy are not significantly different from independent ages of prominent events for ice older than the historical record and younger than approximately 50,000 years. Visible observations are not greatly degraded by "brittle ice" or many other core-quality problems, allowing construction of long, consistently sampled time series. High accuracy requires careful study of the core by dedicated observers. STUDY NOTES: Depths of mid-summer as determined separately from ECM and visual stratigraphy in the GISP2-D ice core. Also given are calculated layer thicknesses (true and ice equivalent) and calculated accumulation rates, all in meters. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Alley, R.B. Investigator : Shuman, C.A. Investigator : Meese, D.A. Investigator : Gow, A.J. Investigator : Taylor, K.C. Investigator : Cuffey, K.M. Investigator : Fitzpatrick, J.J. Investigator : Grootes, P.M. Investigator : Zielinski, G.A. Investigator : Ram, M. Investigator : Spinelli, G. Investigator : Elder, B. 1997-11-30 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/17820 https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/physical/visual.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/physical/strat.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/physical/visual.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/physical/strat.txt English https://www.ncdc.noaa.gov/paleo/study/17820 https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/physical/visual.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/physical/strat.txt R. B. Alley, C. A. Shuman, D. A. Meese, A. J. Gow, K. C. Taylor, K. M. Cuffey, J. J. Fitzpatrick, P. M. Grootes, G. A. Zielinski, M. Ram, G. Spinelli, B. Elder1997Visual-stratigraphic dating of the GISP2 ice core: Basis, reproducibility, and applicationJournal of Geophysical Research: Oceans102C1226367-2638110.1029/96JC03837http://onlinelibrary.wiley.com/enhanced/doi/10.1029/96JC03837/ START YEAR: 50000 cal yr BP * END YEAR: 0 cal yr BP -38.5 72.6 -38.5 72.6