skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Re-calibration of the apparent 25,000 to 35,000 ybp sea level high stand: Just a moment in time some 55,000 to 70,000 years ago

Abstract

Occurrences of shallow marine and strand line sediments at or near the elevation of modern mean sea level with radiocarbon dates in the range of 25,000--35,000 ybp have been reported from the Delmarva Peninsula to the Florida Peninsula. Such dates are in conflict with established sea level curves and have consequently been written off as much older samples contaminated with small amounts of young carbon. An alternate hypothesis is that the assumed near constancy of the galactic cosmic ray (GCR) flux and consequently the C-14 production rate is not totally correct. Be-10 concentrations from ice cores suggests that possibly twice in the last 100,000 years the earth has been briefly subjected to greatly enhanced GCR fluxes. Modeling effects of the increased but brief GCR flux on the total C-14 concentrations in the ocean and biosphere suggests that apparent C-14 dates of 25K to 35K ybp on certain marine deposits may actually reflect deposition during a very brief period of time somewhere between 55K to 70K ybp. Deposits possibly effected include but are not restricted to: an unnamed beach/shore face deposit at Mockhorn Is. Virginia, Diamond City Clay at Cape Lookout NC, Cape Fear Coquina in southeastern NC, Silver Bluff atmore » Sapelo Is. GA, and an unnamed coarse sand at St. George Is., FL. Such deposits are depositionally associated with strand line processes, either near shore, beach, or estuarine. Characteristics of the C-14 dates from such deposits include great variability in age ranges for spatially close samples including association with non-finite samples and apparent violation of the principle of superposition where older material overlies apparently younger. Interpretation of such deposits suggest deposition at or near sea level during a period of falling sea level. Correlation of such deposits north to south along the Atlantic coast suggest continued influence of the glacial forebulge and deposition topographically 5 to 10 meters below modern mean sea level.« less

Authors:
 [1]
  1. Univ. of North Carolina, Wilmington, NC (United States). Dept. of Earth Sciences
Publication Date:
OSTI Identifier:
6120284
Report Number(s):
CONF-9304188-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Journal Name:
Geological Society of America, Abstracts with Programs; (United States)
Additional Journal Information:
Journal Volume: 25:4; Conference: 42. annual Geological Society of America (GSA) Southeastern Section meeting, Tallahassee, FL (United States), 1-2 Apr 1993; Journal ID: ISSN 0016-7592
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; GEOLOGIC DEPOSITS; AGE ESTIMATION; US EAST COAST; PALEOCLIMATOLOGY; BERYLLIUM 10; CARBON 14; COASTAL REGIONS; COSMIC RAY FLUX; DRILL CORES; ERRORS; ICE CAPS; ISOTOPE DATING; SEA LEVEL; ALKALINE EARTH ISOTOPES; BERYLLIUM ISOTOPES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; CARBON ISOTOPES; DEVELOPED COUNTRIES; EVEN-EVEN NUCLEI; ICE; ISOTOPES; LEVELS; LIGHT NUCLEI; NORTH AMERICA; NUCLEI; PALEONTOLOGY; RADIATION FLUX; RADIOISOTOPES; USA; YEARS LIVING RADIOISOTOPES; 580000* - Geosciences

Citation Formats

Dockal, J A. Re-calibration of the apparent 25,000 to 35,000 ybp sea level high stand: Just a moment in time some 55,000 to 70,000 years ago. United States: N. p., 1993. Web.
Dockal, J A. Re-calibration of the apparent 25,000 to 35,000 ybp sea level high stand: Just a moment in time some 55,000 to 70,000 years ago. United States.
Dockal, J A. 1993. "Re-calibration of the apparent 25,000 to 35,000 ybp sea level high stand: Just a moment in time some 55,000 to 70,000 years ago". United States.
@article{osti_6120284,
title = {Re-calibration of the apparent 25,000 to 35,000 ybp sea level high stand: Just a moment in time some 55,000 to 70,000 years ago},
author = {Dockal, J A},
abstractNote = {Occurrences of shallow marine and strand line sediments at or near the elevation of modern mean sea level with radiocarbon dates in the range of 25,000--35,000 ybp have been reported from the Delmarva Peninsula to the Florida Peninsula. Such dates are in conflict with established sea level curves and have consequently been written off as much older samples contaminated with small amounts of young carbon. An alternate hypothesis is that the assumed near constancy of the galactic cosmic ray (GCR) flux and consequently the C-14 production rate is not totally correct. Be-10 concentrations from ice cores suggests that possibly twice in the last 100,000 years the earth has been briefly subjected to greatly enhanced GCR fluxes. Modeling effects of the increased but brief GCR flux on the total C-14 concentrations in the ocean and biosphere suggests that apparent C-14 dates of 25K to 35K ybp on certain marine deposits may actually reflect deposition during a very brief period of time somewhere between 55K to 70K ybp. Deposits possibly effected include but are not restricted to: an unnamed beach/shore face deposit at Mockhorn Is. Virginia, Diamond City Clay at Cape Lookout NC, Cape Fear Coquina in southeastern NC, Silver Bluff at Sapelo Is. GA, and an unnamed coarse sand at St. George Is., FL. Such deposits are depositionally associated with strand line processes, either near shore, beach, or estuarine. Characteristics of the C-14 dates from such deposits include great variability in age ranges for spatially close samples including association with non-finite samples and apparent violation of the principle of superposition where older material overlies apparently younger. Interpretation of such deposits suggest deposition at or near sea level during a period of falling sea level. Correlation of such deposits north to south along the Atlantic coast suggest continued influence of the glacial forebulge and deposition topographically 5 to 10 meters below modern mean sea level.},
doi = {},
url = {https://www.osti.gov/biblio/6120284}, journal = {Geological Society of America, Abstracts with Programs; (United States)},
issn = {0016-7592},
number = ,
volume = 25:4,
place = {United States},
year = {Mon Mar 01 00:00:00 EST 1993},
month = {Mon Mar 01 00:00:00 EST 1993}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share: