Debra A Willard, Ph.D.
I am a palynologist (pollen and spores) with expertise in paleoecology and biostratigraphy. My biostratigraphic expertise extends from the Carboniferous to the Holocene, with an emphasis on Euramerica (Paleozoic) and the Northern Hemisphere. My paleoecological expertise includes the late Paleozoic and the Paleogene to Holocene intervals.
Editorial Boards
- Global and Planetary Change
- Frontiers in Ecology and Evolution – Paleoecology section Review Editor
- Quaternary
- Review of Palaeobotany and Palynology
Professional Experience
2021-Present Research Geologist, US Geological Survey, Reston, Virginia
2011-2021 Coordinator, USGS Land Change Science Program
1991-2011 Research Geologist, US Geological Survey, Reston, Virginia
1990-1991 Postdoctoral Researcher, National Museum of Natural History, Smithsonian Institution, Washington, DC
Education and Certifications
University of Illinois at Urbana-Champaign - Ph.D., Botany 1990
University of Illinois at Urbana-Champaign - M.S., Botany 1985
The Pennsylvania State University - B.S., Botany 1982
Stephens College - A.A., Geology 1980
Affiliations and Memberships*
American Geophysical Union
Geological Society of America
The Palynological Society
Science and Products
Filter Total Items: 105
Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay
Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture...
Authors
Steven Colman, P.C. Baucom, J.F. Bratton, T. Cronin, J. P. McGeehin, D. Willard, A.R. Zimmerman, P.R. Vogt
The Florida Everglades ecosystem: climatic and anthropogenic impacts over the last two millennia The Florida Everglades ecosystem: climatic and anthropogenic impacts over the last two millennia
No abstract available.
Authors
Debra Willard, Charles Holmes, Lisa Weimer
Long-term patterns of vegetation and salinity change in the Lake Pontchartrain region, Louisiana Long-term patterns of vegetation and salinity change in the Lake Pontchartrain region, Louisiana
No abstract available.
Authors
Debra A. Willard, T. Cronin, S. E. Ishman, Marci Marot
Bedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf Bedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf
Two piston cores from the Eurasian flank of Lomonosov Ridge near lat 88.9°N, long 140°E provide the first samples of bedrock from this high-standing trans-Arctic ridge. Core 94-PC27 sampled nonmarine siltstone similar in facies and age to uppermost Triassic to lower Lower Jurassic and mid– Lower Cretaceous beds in the 4 to > 5 km Mesozoic section on Franz Josef Land, on the outer Barents...
Authors
Arthur Grantz, Victoria Pease, Debra Willard, R. L. Phillips, David Clark
Pollen assemblages as paleoenvironmental proxies in the Florida Everglades Pollen assemblages as paleoenvironmental proxies in the Florida Everglades
Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environments are distinguishable from the pollen record and that they are useful proxies for hydrologic and edaphic parameters. Vegetation types sampled include sawgrass marshes, cattail marshes, sloughs with floating aquatics, wet prairies...
Authors
Debra A. Willard, L. M. Weimer, W.L. Riegel
Effects of climate variability and human activities on Chesapeake Bay and the implications for ecosystem restoration Effects of climate variability and human activities on Chesapeake Bay and the implications for ecosystem restoration
Chesapeake Bay, the Nation’s largest and most productive estuary (fig. 1), faces complex environmental issues related to nutrients and oxygen, turbidity and sedimentation, toxic dinoflagellates, sea-level rise, and coastal erosion. The Chesapeake Bay Program (CBP) is a partnership among the Chesapeake Bay Commission, the Federal Government, the District of Columbia, and the States of...
Authors
Thomas Cronin, Debra Willard, Scott Phillips
Climatic variability in the eastern United States over the past millennium from Chesapeake Bay sediments Climatic variability in the eastern United States over the past millennium from Chesapeake Bay sediments
Salinity oscillations caused by multidecadal climatic variability had major impacts on the Chesapeake Bay estuarine ecosystem during the past 1000 yr. Microfossils from sediments dated by radiometry (14C, 137Cs, 210Pb) and pollen stratigraphy indicate that salinity in mesohaline regions oscillated 10-15 ppt during periods of extreme drought (low fresh-water discharge) and wet climate...
Authors
Thomas Cronin, Debra Willard, A. Karlsen, S. Ishman, S. Verardo, John McGeehin, R. Kerhin, C. Holmes, S. Colman, A. Zimmerman
Historical trends in Chesapeake Bay dissolved oxygen based on benthic foraminifera from sediment cores Historical trends in Chesapeake Bay dissolved oxygen based on benthic foraminifera from sediment cores
Environmentally sensitive benthic foraminifera (protists) from Chesapeake Bay were used as bioindicators to estimate the timing and degree of changes in dissolved oxygen (DO) over the past five centuries. Living foraminifers from 19 surface samples and fossil assemblages from 11 sediment cores dated by210Pb,137Cs,14C, and pollen stratigraphy were analyzed from the tidal portions of the...
Authors
A.W. Karlsen, T. Cronin, S.E. Ishmans, Debra A. Willard, R. Kerhin, C. Holmes, M. Marot
Middle Pliocene paleoenvironmental reconstruction; PRISM2 Middle Pliocene paleoenvironmental reconstruction; PRISM2
No abstract available.
Authors
H.J. Dowsett, J.A. Barron, R.Z. Poore, R.S. Thompson, T. Cronin, S. E. Ishman, Debra A. Willard
Preliminary paleontologic report on core 37 from Pass Key, Everglades National Park, Florida Bay Preliminary paleontologic report on core 37 from Pass Key, Everglades National Park, Florida Bay
Sediments from Pass Key core 37, in eastern Florida Bay (N 25.1478, W 80.5745) record a history of rapid sedimentation during this century. The lowest portion of the core contains benthic fauna indicative of relatively low salinities and sparse seagrass coverage. This period is followed by an increase in salinity and seagrass. In the middle portion of the core, a slight decrease in...
Authors
G. L. Brewster-Wingard, S. E. Ishman, N.J. Waibel, Debra Willard, Lucy Edwards, C. Holmes
A record of ecosystem change, Manatee Bay, Barnes Sound, Florida A record of ecosystem change, Manatee Bay, Barnes Sound, Florida
No abstract available.
Authors
Scott Ishman, Thomas Cronin, G. Brewster-Wingard, Debra Willard, David Verardo
Phanerozoic stratigraphy of Northwind Ridge, magnetic anomalies in the Canada Basin, and the geometry and timing of rifting in the Amerasia Basin, Arctic Ocean Phanerozoic stratigraphy of Northwind Ridge, magnetic anomalies in the Canada Basin, and the geometry and timing of rifting in the Amerasia Basin, Arctic Ocean
Cores from Northwind Ridge, a high-standing continental fragment in the Chukchi borderland of the oceanic Amerasia basin, Arctic Ocean, contain representatives of every Phanerozoic system except the Silurian and Devonian systems.Cambrian and Ordovician shallow-water marine carbonates in Northwind Ridge are similar to basement rocks beneath the Sverdrup basin of the Canadian Arctic...
Authors
A. Grantz, D.L. Clark, R. L. Phillips, S.P. Srivastava, C.D. Blome, L.-B. Gray, H. Haga, B. Mamet, D.J. McIntyre, D. McNeil, M.B. Mickey, M. Mullen, B.I. Murchey, C.A. Ross, C.H. Stevens, Norman Silberling, J.H. Wall, Debra A. Willard
Science and Products
Filter Total Items: 105
Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay
Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture...
Authors
Steven Colman, P.C. Baucom, J.F. Bratton, T. Cronin, J. P. McGeehin, D. Willard, A.R. Zimmerman, P.R. Vogt
The Florida Everglades ecosystem: climatic and anthropogenic impacts over the last two millennia The Florida Everglades ecosystem: climatic and anthropogenic impacts over the last two millennia
No abstract available.
Authors
Debra Willard, Charles Holmes, Lisa Weimer
Long-term patterns of vegetation and salinity change in the Lake Pontchartrain region, Louisiana Long-term patterns of vegetation and salinity change in the Lake Pontchartrain region, Louisiana
No abstract available.
Authors
Debra A. Willard, T. Cronin, S. E. Ishman, Marci Marot
Bedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf Bedrock cores from 89° North: Implications for the geologic framework and Neogene paleoceanography of Lomonosov Ridge and a tie to the Barents shelf
Two piston cores from the Eurasian flank of Lomonosov Ridge near lat 88.9°N, long 140°E provide the first samples of bedrock from this high-standing trans-Arctic ridge. Core 94-PC27 sampled nonmarine siltstone similar in facies and age to uppermost Triassic to lower Lower Jurassic and mid– Lower Cretaceous beds in the 4 to > 5 km Mesozoic section on Franz Josef Land, on the outer Barents...
Authors
Arthur Grantz, Victoria Pease, Debra Willard, R. L. Phillips, David Clark
Pollen assemblages as paleoenvironmental proxies in the Florida Everglades Pollen assemblages as paleoenvironmental proxies in the Florida Everglades
Analysis of 170 pollen assemblages from surface samples in eight vegetation types in the Florida Everglades indicates that these wetland sub-environments are distinguishable from the pollen record and that they are useful proxies for hydrologic and edaphic parameters. Vegetation types sampled include sawgrass marshes, cattail marshes, sloughs with floating aquatics, wet prairies...
Authors
Debra A. Willard, L. M. Weimer, W.L. Riegel
Effects of climate variability and human activities on Chesapeake Bay and the implications for ecosystem restoration Effects of climate variability and human activities on Chesapeake Bay and the implications for ecosystem restoration
Chesapeake Bay, the Nation’s largest and most productive estuary (fig. 1), faces complex environmental issues related to nutrients and oxygen, turbidity and sedimentation, toxic dinoflagellates, sea-level rise, and coastal erosion. The Chesapeake Bay Program (CBP) is a partnership among the Chesapeake Bay Commission, the Federal Government, the District of Columbia, and the States of...
Authors
Thomas Cronin, Debra Willard, Scott Phillips
Climatic variability in the eastern United States over the past millennium from Chesapeake Bay sediments Climatic variability in the eastern United States over the past millennium from Chesapeake Bay sediments
Salinity oscillations caused by multidecadal climatic variability had major impacts on the Chesapeake Bay estuarine ecosystem during the past 1000 yr. Microfossils from sediments dated by radiometry (14C, 137Cs, 210Pb) and pollen stratigraphy indicate that salinity in mesohaline regions oscillated 10-15 ppt during periods of extreme drought (low fresh-water discharge) and wet climate...
Authors
Thomas Cronin, Debra Willard, A. Karlsen, S. Ishman, S. Verardo, John McGeehin, R. Kerhin, C. Holmes, S. Colman, A. Zimmerman
Historical trends in Chesapeake Bay dissolved oxygen based on benthic foraminifera from sediment cores Historical trends in Chesapeake Bay dissolved oxygen based on benthic foraminifera from sediment cores
Environmentally sensitive benthic foraminifera (protists) from Chesapeake Bay were used as bioindicators to estimate the timing and degree of changes in dissolved oxygen (DO) over the past five centuries. Living foraminifers from 19 surface samples and fossil assemblages from 11 sediment cores dated by210Pb,137Cs,14C, and pollen stratigraphy were analyzed from the tidal portions of the...
Authors
A.W. Karlsen, T. Cronin, S.E. Ishmans, Debra A. Willard, R. Kerhin, C. Holmes, M. Marot
Middle Pliocene paleoenvironmental reconstruction; PRISM2 Middle Pliocene paleoenvironmental reconstruction; PRISM2
No abstract available.
Authors
H.J. Dowsett, J.A. Barron, R.Z. Poore, R.S. Thompson, T. Cronin, S. E. Ishman, Debra A. Willard
Preliminary paleontologic report on core 37 from Pass Key, Everglades National Park, Florida Bay Preliminary paleontologic report on core 37 from Pass Key, Everglades National Park, Florida Bay
Sediments from Pass Key core 37, in eastern Florida Bay (N 25.1478, W 80.5745) record a history of rapid sedimentation during this century. The lowest portion of the core contains benthic fauna indicative of relatively low salinities and sparse seagrass coverage. This period is followed by an increase in salinity and seagrass. In the middle portion of the core, a slight decrease in...
Authors
G. L. Brewster-Wingard, S. E. Ishman, N.J. Waibel, Debra Willard, Lucy Edwards, C. Holmes
A record of ecosystem change, Manatee Bay, Barnes Sound, Florida A record of ecosystem change, Manatee Bay, Barnes Sound, Florida
No abstract available.
Authors
Scott Ishman, Thomas Cronin, G. Brewster-Wingard, Debra Willard, David Verardo
Phanerozoic stratigraphy of Northwind Ridge, magnetic anomalies in the Canada Basin, and the geometry and timing of rifting in the Amerasia Basin, Arctic Ocean Phanerozoic stratigraphy of Northwind Ridge, magnetic anomalies in the Canada Basin, and the geometry and timing of rifting in the Amerasia Basin, Arctic Ocean
Cores from Northwind Ridge, a high-standing continental fragment in the Chukchi borderland of the oceanic Amerasia basin, Arctic Ocean, contain representatives of every Phanerozoic system except the Silurian and Devonian systems.Cambrian and Ordovician shallow-water marine carbonates in Northwind Ridge are similar to basement rocks beneath the Sverdrup basin of the Canadian Arctic...
Authors
A. Grantz, D.L. Clark, R. L. Phillips, S.P. Srivastava, C.D. Blome, L.-B. Gray, H. Haga, B. Mamet, D.J. McIntyre, D. McNeil, M.B. Mickey, M. Mullen, B.I. Murchey, C.A. Ross, C.H. Stevens, Norman Silberling, J.H. Wall, Debra A. Willard
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government