F RESOURCE ASSESSMENT AND MANAGEMENT
Edwin J. Conklin, Director






FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, State Geologist and Chief






REPORT OF INVESTIGATIONS NO. 103




HIGH RESOLUTION SEA-LEVEL HISTORY FOR THE
GULF OF MEXICO SINCE THE LAST GLACIAL MAXIMUM

by

James H. Balsillie and Joseph F. Donoghue









FLORIDA GEOLOGICAL SURVEY
Tallahassee, Florida
2004 REPORT OF INVESTIGATIONS NO. 103

STATE OF FLORIDA
DEPARTMENT OF ENVIRONMENTAL PROTECTION
Colleen M. Castille, Secretary




DIVISION OF RESOURCE ASSESSMENT AND MANAGEMENT
Edwin J. Conklin, Director






FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, State Geologist and Chief






REPORT OF INVESTIGATIONS NO. 103




HIGH RESOLUTION SEA-LEVEL HISTORY FOR THE
GULF OF MEXICO SINCE THE LAST GLACIAL MAXIMUM

by

James H. Balsillie and Joseph F. Donoghue









FLORIDA GEOLOGICAL SURVEY
Tallahassee, Florida
2004


i
FLORIDA GEOLOGICAL SURVEY








































Printed for the
Florida Geological Survey
Tallahassee, Florida
2004

ISSN 0160-0931


ii REPORT OF INVESTIGATIONS NO. 103

PREFACE





In recent decades, much media attention has been directed at sea-level change and the
possible future implications. Clearly any modest increase in sea-level would have a devastating
impact on human coastal development throughout the world, especially here in Florida where
our state is low in elevation and our population/infrastructure is very near the coast. There is a
great deal of disagreement on the causes of sea-level change, and on the direction and
magnitude of potential change that could be expected in the coming century. The most
important clue we have in predicting the various Earth systems responses in the future, is to
understand similar events that have occurred on Earth in the past.

There have been numerous studies conducted on the sea-level history of the Gulf of
Mexico. These have been individual studies for specific sites using relatively small data sets.
There has not, however, been a comprehensive analysis to compile and assess all available
data to produce a regional sea-level history for the entire region. This report provides such a
compilation and a quantitative analysis. It will be a valuable reference for coastal geoscientists
and engineers as they try to better understand the dynamics of our coastal zone and predict
system response to future events.


Walt
Schmidt,
Ph.D,
P.G.
State
Geologist
and
Chief
Florida
Geological
Survey
















iii FLORIDA GEOLOGICAL SURVEY
ACKNOWLEDGEMENTS


We thank Mark Siddall (Physics Institute, Climate and Environmental Physics, University
of Bern, Bern, Switzerland) for the Red Sea
18
O data set (calibrated to absolute
14
C years BP).
We thank Paula J. Reimer (University of Washington Quaternary Isotope Laboratory, Seattle,
WA) for her advice as to the proper application of the transformation program CALIB Rev 4.4.2.
The review suggestions of Alan Niedoroda (URS Corp., Tallahassee, FL) for detailed plots and
analyses of the younger data sets are acknowledged with thanks. L. James Ladner (Florida
Geological Survey, Tallahassee, FL) brought to our attention the work of Cullen
et al
. (2000).


We thank our Florida Geological Survey colleagues Rick Copeland, Thomas
Greenhalgh, Ron Hoenstine, L. James Ladner, G. Harley Means, Frank Rupert, Walter Schmidt,
and Thomas M. Scott for their peer review of the manuscript.


This project benefited from work resulting from an Office of Naval Research
EuroStrataform project (N00014-03-C-0134). This manuscript is a contribution of IGCP Project
437, "Coastal Environmental Change During Sea-level Highstands".
































iv REPORT OF INVESTIGATIONS NO. 103


CONTENTS



Page

ACKNOWLEDGEMENTS ............................................................................................................ iv

ABSTRACT.................................................................................................................................. ix

INTRODUCTION .......................................................................................................................... 1

RADIOCARBON DATING AND RELATIONSHIPS BETWEEN RADIOCARBON,
CALENDAR, AND ABSOLUTE DATES............................................................................ 3

A NEW GLOBAL SEA-LEVEL RECORD...................................................................................... 5

GULF OF MEXICO SEA-LEVEL CURVE ..................................................................................... 5
Identifying Spurious Data .................................................................................................. 6
Older Data Set ................................................................................................................ 12
Younger Data Sets.......................................................................................................... 12
Combined Data Sets ...................................................................................................... 16

YOUNGER DRYAS .................................................................................................................... 16

A CLOSER LOOK AT SEA-LEVEL FOR THE PAST 6,000 YEARS .......................................... 19

DISCUSSION.............................................................................................................................. 21

CONCLUSIONS.......................................................................................................................... 22

REFERENCES ........................................................................................................................... 23

TABLES

Table 1. Sea-level
14
C data sets used in this study. .................................................................. 6

Table 2. Some average characteristics of the Gulf of Mexico sea-level data sets..................... 12

Table 3. Some delimiting dates for the beginning and end of the Younger Dryas ..................... 19

FIGURES

Figure 1. Relationship between
14
C years BP (present = 1950 AD), calendar years, and
absolute years BP using the IntCal98 data set for terrestrial material (Stuiver
et
al
., 1998a) , and the Marine98 data set for marine material (Stuiver
et al.
, 1998b). ......... 4

Figure 2. Global (eustatic) sea-level data, including the Red Sea data of Siddall
et al.

(2003), augmented with coral reef data of Fairbanks (1989, 1990) from
Barbados, Bard
et al.
(1996) from Tahiti, and Edwards
et al
., (1993) from New
Guinea. A 7-point floating average has been fitted to the data sets................................ 7


v FLORIDA GEOLOGICAL SURVEY
Figure 3. nth-order polynomial editing reference curves fited to 7-point floating average
curves of Figure 2, for data with ages less than approximately 6,000 years and
greater than approximately 6,000 years............................................................................ 8

Figure 4. Gulf of Mexico
14
C sea-level data. Upper panel illustrates the Gulf of Mexico
data set, with the global (eustatic) reference curve from Figure 3 superimposed.
Also shown is an acceptance envelope containing
96.43%
of data (3.6% of data
lie outside the envelope).

Only some of younger data (less that 6,000
14
C years
BP are plotted) in the upper panel in order to provide greater clarity, although all
those data sets that are affected by the editing process do appear. Lower panel
shows 7-point floating average curve fitted to all Gulf of Mexico data sets; 12
points were rejected from analytical consideration (3.4% of total data). ........................... 9

Figure 5. Gulf of Mexico
14
C sea-level data. Upper panel illustrates the Gulf of Mexico
data set, with the global (eustatic) reference curve from Figure 3 superimposed.
Also shown is an acceptance envelope containing 96.85% of data (3.2% of data
lie outside the envelope).


Only some of younger data (less that 6,000
14
C years
BP are plotted) in the upper panel in order to provide greater clarity, although all
those data sets that are affected by the editing process do appear. Lower panel
shows 7-point floating average curve fitted to all Gulf of Mexico data sets; 12
points were rejected from analytical consideration (3.4% of total data).. ........................ 10

Figure 6. Gulf of Mexico younger data set A for dated sample sets collected offshore
from the present shoreline. 7-point floating average curves have been fitted to
the
14
C and absolute age data sets................................................................................. 13

Figure 7. Gulf of Mexico younger data set B for data sample sets collected onshore from
the present shoreline. 7-point floating average curves ha