Drilling barge used to collect sediment from the floor of Onondaga Lake

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2007–1060 

June 2007 

Prepared in cooperation with Onondaga Lake Partnership and Onondaga Environmental Institute

The stable carbon-isotope composition (δ13C) and total organic carbon content (TOC) of sedimentary organic matter were 

measured in a series of split-spoon samples of lakebed sediment sampled from the middle of Onondaga Lake, Syracuse, New York. 

These samples were analyzed and the results compiled to provide a paleoenvironmental assessment of the lake and its watershed 

following deglaciation between calibrated radiocarbon age 14,000 and 2,000 years before present (Cal BP). 

Carbon-14 (14C) data from split-spoon samples collected in the Onondaga Trough (valley) were used to determine the age of 

sediment deposition throughout the Trough, and the dates of landslides and other post-glacial events in the Onondaga Trough. These 

14C data have also been correlated with the δ13C data to provide a context for understanding the glacial recessional sequence in the 

Onondaga Trough.

Paleoenvironmental Assessment and 

Deglacial Chronology of the Onondaga Trough, 

Onondaga County, New York
Tully

Valley

Valley Heads

Moraine

Onondaga Lake

Seneca

River

Onondaga

Onondaga Creek West Branch

Mudboils

Landslides

Ninemile

Creek

Onondaga Creek

Webster Rd. slide

Sulfur Hole slide

LaFayette

Otisco

Lake

Skaneateles Lake

Harbor Brook

Ley Creek Creek

Piezometer

Onondaga

 Creek

0 2.5 5 10 KILOMETERS

0 1 3 5 MILES Base from US Geological Survey, 1998, 

Digital Elevation Models for New York State,

Universal Transverse Mercator projection,

Zone 18, NAD 83

Syracuse

NEW

YORK

ONONDAGA

 COUNTY

Seneca Lake

 City of

Syracuse

Explanation

 Direction of streamflow

Location and name of 

 sampling site

76°17'30" 76°7'30"

42°50'

43°7'30"

Saddle

Parkway

OL-STA20003

 WB1-8

SB-13BR

Kirkpatrick

H&A RTF

H&A LB

H&A UB

South Deep

 WB1-8

SB-28BR

Spencer St.

Village of 

 Tully

Figure 1.  Shaded-relief map of the Onondaga Trough

(from the Valley Heads Moraine to Onondaga Lake) and

locations where organic samples were collected for

age dating.

2

Introduction

The U.S. Geological Survey, in cooperation with the 

Onondaga Lake Partnership and Onondaga Environmental 

Institute, has been studying the hydrogeology of the 

Onondaga Trough since 2002 to determine the movement 

and concentration of naturally occurring brine in the glacial 

valley-fill aquifer. Numerous shallow and deep test holes 

have been drilled to determine the glacial and water-quality 

stratigraphy in the Onondaga Trough. Organic materials were 

recovered from the Onondaga Creek, Ninemile Creek, and 

Harbor Brook valleys, and from lakebed sediments in Onondaga 

Lake (fig. 1) and age-dated with carbon-isotope analysis 

techniques. This report summarizes the carbon-isotope data 

collected from 1996 through 2006 in the Onondaga Trough. 

The results of these analyses provide a means to understand 

the deglaciation of the watershed and the development of the 

watershed from barren glacial sediment to a forested ecosystem.

Methods of Investigation 

A number of shallow, split-spoon samples from recent 

USGS and ongoing (2006) construction and contaminantinvestigation projects yielded an assortment of organic materials 

(wood, reeds, seeds) and sediment samples that were age-dated 

using carbon-isotope analysis techniques. The assessment 

techniques utilized isotopic forms of Carbon-13 and Carbon-14, 

and the analyses were carried out at the Environmental Science 

Stable Isotope Laboratory (EaSSIL) at the State University 

of New York–College of Environmental Science and Forestry 

(SUNY-ESF) and at several accelerated mass spectrometer 

laboratories after samples of organic matter were prepared at the 

USGS Carbon-14 Laboratory in Reston, Virginia.

Determination of Stable Carbon Isotope, Total 

Organic Matter, and Carbonate Content 

in Onondaga Lake Sediments

The stable carbon-isotope composition (δ13C) and total 

organic carbon content (TOC) of sedimentary organic matter 

were measured in a series of split-spoon samples taken at 5-foot 

intervals in lakebed sediments in the middle of Onondaga Lake 

at the ‘Saddle’ location (fig. 1). Five-centimeter subsections of 

these split-spoon samples were freeze-dried and ground to a 

fine powder. This dry sediment was weighed into small silver 

boats and then fumed under an acidic atmosphere to remove any 

inorganic carbonate material. These carbonate-free sediments 

then were analyzed at EaSSIL at SUNY-ESF, Syracuse, using 

an elemental analyzer coupled to a stable-isotope-ratio mass 

spectrometer. The total organic carbon and carbonate content 

were measured by using a loss-on-ignition method. Dry 

sediment was placed in ceramic crucibles and heated to 550oC 

to release organic matter; further heating to 1000oC released 

inorganic carbonate materials (Dean, 1974).

Determination of Carbon-14 Age Dates

The Carbon-14 (14C) technique was used to age-date 

organic material from split-spoon samples of glacial sediment 

retrieved in the Onondaga Trough. These samples were 

obtained without the introduction of contaminant carbon from 

land surface and near-land-surface sources, such as roots and 

anthropogenic fill. Under careful examination, the recovered 

sediment samples occasionally included pieces of organic 

matter (for example, peat-like material, a large seed, or a piece 

of wood) that were buried contemporaneously with these 

sediments, hundreds to thousands of years ago. The organic 

materials taken from the split spoons were kiln dried, prepared 

for shipment, and then sent to a 14C laboratory where their ages 
Stable Carbon Isotopes (12C and 13C) and the Environment 

The stable isotopes of carbon (12C and 13C) occur naturally in all plants and animals, and the relative amounts 

of these stable isotopes can be used to understand natural processes and the state of the environment. Carbon exists 

primarily as the 12C isotope (98.89%), but a small fraction (1.11%) is present as 13C. Although the different isotopes 

possess the same fundamental chemical properties, in that they both behave chemically like carbon, they differ in the 

rates at which they react as a result of the difference in their atomic masses, with 13C reacting at a slightly slower rate 

than 12C.

The ratio of the stable isotopes of carbon (13C/12C) is measured using a stable isotope ratio mass spectrometer, 

and the ratio is expressed in parts per thousand or per mil (‰), relative to an international standard known as Vienna 

Peedee Belemnite (V-PDB):

δ13C (‰) = [(Rsample/Rstandard) – 1] * 1000 (1)

where

Rsample = 13C/12C of the sample, 

and 

Rstandard = 13C/12C of V-PDB.

The stable carbon isotope value (d13C) of sedimentary organic matter has the signature of the organic matter 

that was present in the lake in the past. Therefore, the d13C ratios in sediments can provide information about past 

environments in and around lakes. The stable isotope signatures of some land plants differ from that of algae; 

therefore we can use d13C ratios to discern major organic inputs to lakes. Additionally, algae and other aquatic plants 

photosynthesize and preferentially use more 12C than 13C to produce organic material. The stable isotope signature of 

plant organic matter, which is subsequently preserved in sediments, can be used to determine the rate at which algae 

are growing. When algae grow rapidly, they utilize more 13C than under normal conditions, and this will be reflected in 

the production of organic matter that is enriched in 13C, which is reflected in a more positive d13C value.

More details on the use of stable isotopes in environmental studies are available at: http://wwwrcamnl.wr.usgs.

gov/isoig/res/funda.html

Streambank exposure along Onondaga Creek at the sulfur-hole landslide area.

3
4

were determined. Results of these analyses are reported as an 

age in calendar years or radiocarbon years “before present” 

(BP), with 1950 serving as the base year. Analysis algorithms 

such as the radiocarbon calibration program (Stuiver and 

Reimer, 1993) can correct for atmospheric variations of 14C 

over time and report calibrated ages (for example, calibrated 

years before present (Cal BP)), or calendar years before 

present (BC/AD).

In the Onondaga Trough, organic matter from several 

different sediment sources was considered for age dating. The 

samples included organic matter incorporated into the glacial 

sediment during and immediately following the last major 

recession of glacial ice from the Onondaga Trough—from the 

Tully (Valley Heads) Moraine to the outlet of Onondaga Lake 

(fig. 1). Possible sources of organic material in post-glacial 

sediment include (1) alluvial material (carried in a tributary 

stream) from the surrounding uplands to the valley floor, 

(2) landslides that incorporated both glacial and post-glacial 

sediment and organic material, or (3) lake-bottom sediments 

and organic material which slowly accumulated on the floor 

of Onondaga Lake and were transported there by tributary 

streams. The results of these 14C and δ13C analyses provide the 

basis for assessing the post-glacial sediment chronology and 

paleoenvironment of the Onondaga Trough.

Regional Deglaciation Framework

 Ridge (2003) provides a basis for dating organic 

material across the northeastern United States using glaciallake sediment varves, paleomagnetics, and 14C chronologies. 

Although much of his study was conducted in New England, 

dates for glacial retreat in New York State also were provided. 

Using his regional timeline of Wisconsin-age deglaciation, the 

following “benchmark” dates have been established for central 

New York:

Last glacial maximum–The period of greatest glacial advance 

southward in New York during the Wisconsin period when 

the glacier was south of the New York-Pennsylvania border. 

Estimated time of occurrence is about 24,000 radiocarbon 

years (Cal BP 28,200–27,200 years). (The calibration 

program does not have any data to support calibratedage determinations older than 20,300 radiocarbon years; 

therefore these dates are estimated.)

Advanced Valley Heads ice position–The last major glacial 

readvance in central New York that created the present 

Finger Lakes drainage pattern. Estimated time of occurrence 

is about 14,350 to 13,500 radiocarbon years (Cal BP 

17,200–16,200 years).

Glacial recession from the northeastern U.S.–At this time 

all glacial ice had receded from the northeastern U.S. into 

Canada. Estimated time of occurrence is about 11,400 

radiocarbon years (Cal BP 13,400 years).

These dates provide a general chronology of major glacial 

events in the Finger Lakes region including the Onondaga 

Trough. Based on this timeframe, samples analyzed in this study 

are relatively recent in age—mostly post-glacial sediments 

deposited within the last Cal BP 14,000 years.

•

•

•

Paleoenvironmental History of the 

Onondaga Trough

When glacial ice began to recede from southern New York 

State at about 20,000 years (Cal BP 24,000 years) (fig. 2), the 

region was virtually barren of vegetation, and erosion rates 

were substantial. The process of deglaciation in the Onondaga 

Trough began at about 14,000 years (Cal BP 17,000 years) at 

the Advanced Valley Heads Moraine position, located near 

Tully (fig. 1). Since that time, the climate of the region has 

varied between cold and dry to warm and wet in response to 

global climate variability. These changes in regional climate and 

watershed vegetation succession are recorded in the glacial and 

post-glacial sediments.

Cal BP 14,000 Years to 10,000 Years Ago

Prior to Cal BP 10,000 years ago, terrestrial vegetation 

in the Onondaga Trough was sparse and algal productivity in 

what is now Onondaga Lake was limited. These observations 

are supported by the presence of sediments with relatively 

low carbonate content (fig. 3A) and low stable carbon isotope 

ratio (δ13C, fig. 3B). Supporting evidence from analysis of 

sediments collected from nearby Seneca Lake (about 40 miles 

southwest of Onondaga Lake) indicates that, during this period, 

low temperatures and an unstable climate may have resulted 

in shorter summer growing seasons (Guiles Ellis and others, 

2004). Cold periods were common, including those associated 

with the expansion of glacial Lake Iroquois (Cal BP 14,000 

years) and the Younger Dryas cold period (Cal BP 12,900 to 

11,600 years) (Guiles Ellis and others, 2004). Low temperatures 

and short growing seasons that limit algal productivity, are 

indicated by the small amount of organic and inorganic carbon 

preserved in sediments from this time period.

In the southern part of the watershed, early vegetation 

emerged within the Onondaga Trough uplands, but a minimal 

amount of organic matter was incorporated into the postglacial sediments on the floor of the valley. The few samples 

that contained datable material were preserved in deeper 

lake sediments or in sediment near the lake (OL-STA20003, 

Piezometer, and Spencer St. sites on fig. 1). Only one location 

in the upper watershed (Webster Road slide, fig. 1) yielded 

enough organic material to provide a 14C date from this period. 

The prevalence of samples collected in the post-glacial lake 

sediments indicates a dynamic environment during the Younger 

Dryas period (fig. 2). During this period, cooler temperatures 

and wetter climatic conditions resulted in the transport of much 

of the organic matter found in the lake, where it settled to the 

lake bottom and was preserved. The landslide at Webster Road 

(Cal BP 11,300 years) apparently occurred in a watershed 

with limited vegetation during a period of wetter-than-normal 

precipitation; these conditions may have triggered a landslide 

that buried small trees at this location.
The Theory and Process of Using Carbon Isotopes for Carbon-14 Age Dating

There are three principal forms or isotopes of carbon that occur naturally: Carbon-12 (12C), Carbon-13 (13C), both of 

which are stable in the environment, and Carbon-14 (14C), an unstable or radioactive isotope of carbon. These isotopes are 

present in the environment in the following amounts:

12C - 98.89 percent, 

13C - 1.11 percent and, 

14C - 0.00000000010 percent. 

Thus, one 14C atom exists in nature for every 1,000,000,000,000 (quadrillion) 12C atoms in living material. The radiocarbon 

age-dating method is based on the rate of decay of the radioactive or unstable 14C isotope that is formed in the upper 

atmosphere through the effect of cosmic-ray neutrons bombarding nitrogen 14 (14N). The reaction is:

14N + neutron => 14C + proton. (2)

The 14C formed is rapidly oxidized to carbon dioxide (14CO2) and enters the plant and animal lifecycles through 

photosynthesis, respiration, and uptake into the food chain. Plants and animals that utilize carbon through food chains take 

up various amounts of 14C during their lifetimes that are in equilibrium with the 14C concentrations in the atmosphere. That is, 

the number of 14C atoms and non-radioactive carbon atoms stay about the same over time. As soon as a plant or animal dies, 

they cease the metabolic function of carbon uptake and the decay cycle of 14C begins. Eventually, the 14C atom emits a beta 

particle from the nucleus of the 14C atom and decays back to 14N. 

The decay rate for 14C was first measured by Libby and others (1949). They found that, after 5,568 years, half of 

the 14C in an original sample decayed and after the next 5,568 years, half of that remaining material decayed, and so on. 

Libby measured these half-lives at 5,568 ± 30 years, and this value became known as the Libby half-life. Ten half-lives 

(representing 50,000 to 60,000 calendar years) is the limit of this age-dating technique due to the very small amount of 

radioactive carbon present in a sample after this time. By comparing 14C with modern levels of activity (1890 wood corrected 

for decay to 1950 A.D.) and using the measured half-life, it is possible to calculate a date for the death of the organic 

material in the sample. Later measurements of the Libby half-life indicated the figure was about 3 percent too low and a more 

accurate half-life was determined at 5,730 ± 40 years. This is known as the Cambridge half-life. (To convert a Libby age to 

a Cambridge age, multiply the Libby age by 1.03, although it is common practice to report ages using the Libby half-life.) 

Information about the comparison of these different age calculations is available at: http://www.c14dating.com/int.html

Typical split-spoon sampler used to collect sediment samples from which organic carbon material was analyzed.

5
Regional glacial

framework

TIME, IN 

CAL BP YEARS

Last glacial

maximum

Advanced

Valley Heads

Moraine

0 Present day

Younger Dryas

 (Cold, wet period)

2,000

10,000

Period of record analyzed 

from the Saddle core for

D13C, carbonate, and total

organic carbon analyses

14,000

4,000

Onondaga Lake

and nearshore area

calibrated calendar 

14C dates, in years

Piezometer

Kirkpatrick

Spencer St.

Parkway

Saddle

13BR

OL-STA20003

South

Deep

10,000

14,000

2,000

4,000

6,000

8,000

12,000

6,000

8,000

12,000

6,000

4,000

10,000

8,000

12,000

14,000

2,000

Tully Valley

calibrated calendar 

14C dates, in years

Webster Rd.

Slide 2

Webster Rd.

Slide 1

Sulfur Hole

landslide area

Onondaga Ck.

Alluvial fan

Glacial ice retreats

from northeastern

U.S.

EXPLANATION

Data point representing one sample at a particular site.

Time period representing results of multiple 14C

analyses collected at one site.

14,000

2,000

6,000

4,000

10,000

8,000

12,000

16,000

20,000

18,000

24,000

22,000

26,000

28,000

Mid-Holocene

Hypsithermal

(Warm, wet period

in New York State)

1

3

2

1

1

Ridge (2003)

Guiles Ellis and others

(2004)

Dwyer and others

(1996)

1

2

3

SB28 BR Tully Valley

1993 landslide 

Chronostratigraphic Framework in the Onondaga Trough

1

Glacial

Lake Iroquois

30,000

0 0 0 Shown in fig. 3

Figure 2.  Comparison of the New York State deglaciation chronology with

the mid-Onondaga Lake Saddle core analyses and 14C analyses collected in

and near Onondaga Lake and in the Tully Valley. (δ13C, carbonate, and total

organic carbon results shown in fig. 3, and 14C results shown in table 1.)

6
Figure 3.  Analytical results from split-spoon samples taken from the middle of Onondaga Lake at the Saddle drill hole (location

shown on fig. 1) (A) percent carbonate, (B) stable carbon isotope (δ13C), and (C) total organic carbon.

PERCENT CARBONATE

0 10 20 30 40

DEPTH, IN FEET

0

20

40

60

80

100

120

140

160

180

200

220

240

STABLE CARBON ISOTOPE (D13C),

IN PARTS PER MIL (PER THOUSAND)

-30 -20 -10 0

A B C

TOTAL ORGANIC CARBON,

PERCENT BY WEIGHT

0 1 2 3 4 5

0

20

40

60

80

100

120

140

160

180

200

220

240

Present day

lake bottom

~2,000 yrs

~12,000 yrs

~4,000 yrs

~8,000 yrs

~14,000 yrs

Computed age

of lake-bed

sediments

CAL BP

years

Post-glacial sediments

 Glacial sediments

DEPTH, IN FEET

7

Cal BP 10,000 Years to 4,000 Years Ago

This period was marked by a rapid increase in the amount 

of inorganic carbonate and organic matter (measured as total 

organic carbon) deposited in the sediments (figs. 3A and 3C). 

The increase in carbonate probably resulted from calciumenriched surface runoff from the eroding watershed combined 

with ground water flowing through carbonate-enriched glacial 

sediments, both of which entered Onondaga Creek and 

Onondaga Lake. Carbonate bedrock also is exposed along 

the walls of the Onondaga Trough just south of Onondaga 

Lake, and water discharging from this bedrock may have been 

an additional source of calcium-enriched water flowing into 

Onondaga Creek. Similarly, the increase in organic matter in 

the lake-bottom sediments may have resulted from an increase 

in the amount of organic materials delivered to the lake by 

surface water as early vegetation (grasses, woody shrubs and 

some small trees) developed after the retreat of the glacial ice. 

This increase in organic-matter delivery to the lake would have 

increased the amount and concentration of organic nutrients 

present in the lake and stimulated the growth of algae.

The large increase in the stable isotope (δ13C) values (to 

less-negative numbers) in sedimentary organic matter between 

Cal BP 5,000 and 3,000 years (fig. 3B) further supports the 

hypothesis that algal productivity increased dramatically in the 

lake during this period. During periods of rapid growth, algae 

typically will use more 13C than usual because they deplete the 

pool of dissolved carbon dioxide in the water, and therefore 

the amount of inorganic bicarbonate in the lake increases. This 

rapid growth of algae probably occurred during times of warmer 

temperatures and when the lake became enriched in carbonate, 

as evidenced by the increase in carbonate content of lakebed 

sediments between Cal BP 5,000 and 3,000 years (fig. 3A). The 

increased inflow of carbonate from the surrounding watershed, 

together with the increased nutrient input from the developing 

watershed, would have resulted in algal blooms and associated 

whiting events (see sidebar, p. 9).

The increased productivity in the watershed is also 

evidenced by the greater amount of 14C organic matter observed 

in the post-glacial sediments in the lake and throughout the 

watershed. In and near the lake, greater amounts of organic 

material are present within the mid- to upper-sediment 

sequence. With maturing vegetation during this period, a 

greater diversity of organic materials is present throughout the 

Onondaga Trough (table 1). In the Tully Valley, the extension 

of an alluvial fan buried several large trees (Onondaga 

Creek #1, table 1) and the landslide at Sulfur Hole and the 

second landslide at Webster Road indicate that even within a 

maturing watershed, a period of wetter-than-normal climate 

conditions could have initiated shallow-slope landslides (Pair 

and others, 2000) and the burial of organic matter in and near 

Onondaga Creek.
8

Table 1.  Carbon-14 laboratory results for Onondaga Trough organic samples.

[δ13C, Stable Carbon isotope Carbon-13; 14C, Carbon isotope Carbon-14; years BP, years before present; ft, feet] 

Sample 

Number1

Sample identification and depth 

below land or lakebed surface, 

if available

Material δ13C estimated

14C Age, 

(Radiocarbon 

years BP)

Calibrated age 

(Cal BP years) Laboratory2

WW1863 Onondaga Creek at Webster Road Wood -25 9,870 +/- 40 11,243 +/- 60 CAMS

WW2136 Webster Road (interface 10-8) Wood -25 6,160 +/- 40 7,045 +/- 117 CAMS

WW2137 Webster Road (interface 10-9) Peat -25 6,110 +/- 50 6,973 +/- 121 CAMS

WW3802 Piezometer - 1 (62 ft) Wood -25 10,500 +/- 96 12,477 +/- 402 UA-AMS

WW3803 Piezometer - 2A (62 ft) Wood -25 10,385 +/- 67 12,304 +/- 374 UA-AMS

WW3804 Piezometer - 2B (62 ft) Wood -25 10.356 +/- 79 12,288 +/- 393 UA-AMS

WW3809 Kirkpatrick - 1 (59 ft) Wood -25 7,977 +/- 55 8,841 +/- 164 UA-AMS

WW3810 Kirkpatrick - 2 (30 ft) Wood -25 4,958 +/- 47 5,673 +/- 78 UA-AMS

WW4205 Spencer Street (8.6 ft) Wood -25 840 +/- 40 733 +/- 61 CAMS

WW4206 Spencer Street (13.6 ft) Wood -25 7,305 +/- 40 8,095 +/- 82 CAMS

WW4207 Sulphur hole slide - 1 (middle) Peat -25 4,180 +/- 40 4,690 +/- 82 CAMS

WW4208 Sulphur hole slide - 2 (bottom) Wood -25 4,785 +/- 40 5,530 +/- 69 CAMS

WW4209 Sulphur hole slide - 3 (top) Wood -25 4,135 +/- 40 4,652 +/- 85 CAMS

WW4210 Spencer Street (14.2 ft) Wood -25 7,245 +/- 40 8,188 +/- 943 CAMS

WW4211 Spencer Street (21.2 ft) Wood -25 11,040 +/- 40 13,026 +/- 151 CAMS

WW4213 LaFayette (2.56 ft) Wood -25 Modern Modern CAMS

WW4724 Parkway (73 ft) Wood -25 12,045 +/- 50 14,070 +/- 257 CAMS

WW4868 Saddle (92 ft) Charcoal -25 9,595 +/- 35 10,885 +/- 140 CAMS

WW5509 Onondaga Creek # 1 Wood -25 6,760 +/- 35 7,621 +/- 47 CAMS

WW5564 WB1-8-SB-28BR (43 ft) Plant material -25 170 +/- 35 181 +/- 50 CAMS

WW5565 H&A RTF 206 (23-25 ft) Wood -25 1,995 +/- 35 1,939 +/- 69 CAMS

WW5566 H&A RTF 202 (18-20 ft) Seeds -25 4,120 +/- 35 4,628 +/- 102 CAMS

WW5567 WB1-8SB-13BR (65.5-65.7 ft) Wood -25 4,680 +/- 35 5,395 +/- 80 CAMS

WW5568 WB1-8SB-13BR (78.8-80.0 ft) Peat -25 5,900 +/- 35 6,723 +/- 72 CAMS

WW5569 WB1-8SB-13BR (85.5-86.0 ft) Peat -25 5,985 +/- 35 6,824 +/- 88 CAMS

WW5570 WB1-8SB-13BR (89.5-90.0 ft) Peat -25 6,050 +/- 35 6,893 +/- 98 CAMS

WW5571 OL-STA20003 (33-36 ft) Plant material -25 10,835 +/- 40 12,845 +/- 40 CAMS

WW5572 Onondaga Creek # 2 Wood -25 6,300 +/- 30 7,210 +/- 56 CAMS

WW5573 Onondaga Creek # 3 Wood -25 7,135 +/- 35 7,972 +/- 44 CAMS

WW5574 H&A UB 103-S8 (14-16 ft) Peat -25 7,885 +/- 35 8,686 +/- 96 CAMS

WW5575 H&A LB 107 (12-14 ft) Plant material -25 2,975 +/- 35 3,161 +/- 102 CAMS

WW5576 H&A LB 109 (26-28 ft) Wood -25 10,340 +/- 30 12,147 +/- 98 CAMS

TO1961 South Deep (5.7 ft) Silt -25 5,490 +/- 70 6,290 +/- 121 Isotrace

TO1983 South Deep (15.3 ft) Silt -25 2,960 +/- 50 3,113 +/- 152 Isotrace

1

 Samples were processed in the U.S. Geological Survey Radiocarbon Laboratory in Reston, VA and the Isotrace Laboratory in Toronto, Ontario, Canada. The 

“WW” sample designations were assigned by the USGS lab, and the “TO” sample designations were assigned by the Isotrace lab.

2

 Laboratories: CAMS, Center for Accelerated Mass Spectrometer, Lawrence Livermore Laboratory; UA-AMS, University of Arizona, Accelerated Mass 

Spectrometer Laboratory; Isotrace, Isotrace Radiocarbon Laboratory, Totonto, Ontario, Canada.
Whiting Events

Algal growth is dependent on sunlight and nutrients, and when there is an abundance 

of both, the growth and productivity of algae can increase rapidly. As algal growth 

proceeds under these conditions, the algae utilize large amounts of dissolved carbon 

dioxide which in turn produces large quantities of calcium carbonate due to a chemical 

shift in the equilibrium between dissolved carbon dioxide and inorganic bicarbonate. The 

white calcium carbonate precipitate falls to the floor of the lake and is deposited with 

fine-grained sediment to form marl in what is known as a “whiting event” (Thompson and 

others, 1997). These whiting events are common in carbonate-rich lakes such as the Finger 

Lakes in central New York (Lajewski and others, 2003) including Onondaga Lake. These 

whiting events are characterized by the presence of high concentrations of algae in lakes, 

known as algal blooms, with accompanying high amounts of organic matter in the surface 

waters. The stable-isotope composition of the organic matter associated with these algal 

blooms increases greatly during these events, as does the amount of carbonate present in 

the water. After several weeks, algae begin to die, coalesce, and sink to the lake bottom. 

The organic matter from the algae and carbonate produced by the algae are subsequently 

preserved in the sediments. The sedimentary record of the increased algal productivity, 

subsequent die-off, and whiting event is characterized by relatively high concentrations 

of organic matter, greater carbonate content, and increased stable carbon-isotope ratios 

of the preserved organic matter. This pattern is observed in the sedimentary record of 

Onondaga Lake. Summer temperatures were 2o to 4oC warmer than today (Pielou, 1991; 

Guiles Ellis and others, 2004), which further supports the concept of the increased algal 

productivity in the lake during that period.

Tree stump in the bed of Onondaga Creek, which was found to be over 7,600 years old (Cal BP years).

9

Cal BP 4,000 Years to 

2,000 Years Ago

The decrease in carbonate, the 

δ13C values in sedimentary organic 

matter, and total organic-carbon 

content during this period (figs. 3A, 

3B, and 3C) all indicate that lake algal 

productivity decreased. This decrease 

in algal productivity may have 

been caused by a number of factors 

including decreases in temperature 

and(or) decreases in nutrient input 

to the lake. This period is known to 

have been cooler than the preceding 

period (Mullins, 1998), and evidence 

from analyses of sediments from 

Lake Ontario indicate that reduced 

levels of chemical weathering in its 

tributary watersheds reduced the 

amount of carbonate delivered to it 

(McFadden and others, 2004). The 

lower temperature would have caused 

less algal productivity, resulting in 

smaller amounts of organic carbon 

and inorganic carbonate delivered 

to the sediments through whiting 

events. Continued development of 

vegetation in the watershed may 

have also reduced the amount of 

surface runoff to the lake caused by 

stabilization of the soil and increased 

evapotranspiration of mature 

vegetation. The evidence presented 

here is consistent with the interpreted 

development and stabilization of 

the watershed ecosystem, and the 

subsequent reduction of sediment 

loading to the lake through creeks 

and streams.

Although organic matter 

continued to be deposited throughout 

the watershed during this period, little 

of this material was recovered for 

14C analysis. The only samples that 

contain material from this time period 

are from a section of the Ninemile 

Creek channel that was buried beneath 

waste-bed sediments, and a shallow 

sample from 8 feet below the land 

surface at the Spencer Street site. 

Anthropogenic disturbance of the land 

surface caused by construction and 

landfilling, especially in the present 

city of Syracuse, resulted in the loss 

of much of these materials. When 

sediments in split-spoon samples were 

observed to be possibly disturbed, 

no organic material was collected for 

analysis in these cases.
Estimated Sedimentation Rates in Onondaga Lake 

Carbon-14 (14C) samples collected from Onondaga Lake sediments also can be used to estimate rates of sediment 

accumulation on the floor of the lake after the Wisconsin glacial period ended at about Cal BP 14,000 years. Rates of sediment 

accumulation on the floor of Onondaga Lake were determined through ten analyses of organic material collected from the lake 

bottom (see figure 1 for locations).

Sedimentation rates in the lake declined from Cal BP 14,000 years to the present based on the depth and computed age of 

the Parkway, Saddle, and South Deep samples collected respectively at 57 ft, 36 ft, and 15.3 and 5.7 ft below the lake bed surface. 

Sedimentation rates declined as sedimentation progressed upwards, as shown by the following data.

Depth below lake-bed surface (ft) Sedimentation rate (in/yr)

0.0 – 5.7 0.02

5.7 – 15.3 .04

15.3 – 36 .05

36 – 57 .08

To verify these rates, samples were collected in 2005 from locations below and adjacent to waste-bed materials deposited 

along the eastern lakeshore. These samples were denoted as the WB1-8 SB-series on figure 1 and in table 1, and their 

sedimentation rates were compared to those computed above. From the WB1-8 samples, the early post-glacial sediment at a depth 

of about 35 feet below the lakebed was dated at Cal BP 12,840 years, and from that layer to just below the marl layer, a rate of 

0.075 in/yr was computed. For the uppermost sediment sequence—the Ninemile Creek streambed sample (SB-28BR) down to the 

uppermost marl sample—a sedimentation rate of 0.016 inches per year was computed. These rates agree closely with the early 

sedimentation rate of 0.08 in/yr and the computed present-day sedimentation rate of 0.02 in/yr, respectively. The intervening 

marl/organic layers at this site cannot be used to compute a sedimentation rate owing to the addition of the organic-material 

layers with the accumulation of fine-grained sediment. Although the lake-bed sediment data were collected from several locations 

around the lake, the computed rate of sedimentation, which decreases over the last Cal BP 14,000 years, appears consistent 

around the southern half of the lake.

Streambank exposure along Onondaga Creek adjacent to tree stump picture on the previous page.

10
11

Concluding Discussion

During and immediately following the recession 

of glacial ice from the Valley Heads Moraine around 

14,000 years (Cal BP 17,000 years), the Onondaga watershed 

was virtually barren of vegetation. At the time, erosional rates 

in a series of pro-glacial lake basins in the northward-draining 

watershed, which would become the Onondaga Creek valley, 

were substantially greater than they are today. The West Branch 

valley of Onondaga Creek, when free of glacial ice, discharged 

large amounts of sediment to the Onondaga Valley floor as the 

ice front continued to recede to the north and pro-glacial lake 

levels in the Onondaga Valley declined (Kappel and Miller, 

2005). The steep hillsides in the southern two-thirds of the 

watershed slowly became more stable as over-steepened-slope 

failures (landslides) diminished. These slopes reached a more 

stable configuration as a succession of vegetation types (grasses 

to shrubs and then trees) further stabilized the thin soils on 

these slopes.

Rapid and repeated changes in the post-glacial climates 

alternated from cooler to warmer and drier to wetter periods 

(Dwyer and others, 1996; and Mullins, 1998), These changes 

influenced the stability of slopes and the ability of the 

Onondaga Creek drainage network to transport sediment from 

the steep hillsides of the southern part of the watershed to the 

flatter northern part of the Onondaga Trough and Onondaga 

Lake. In the southern part of the Onondaga Trough (the 

Tully Valley, fig. 1), the two landslides near Webster Road 

at about Cal BP 11,300 years and Cal BP 7,000 years and 

the recent (1993) landslide all attest to slope instability well 

after deglaciation.

Onondaga Lake was part of the much larger Glacial Lake 

Iroquois during the cooler periods that persisted about Cal BP 

14,000 to 13,000 years ago and limited the growth of algae in 

the lake. Beginning in the mid-Holocene Hypsithermal period 

Cal BP 9.000 to 6,500 years ago (fig. 2), temperatures began 

to increase and the lake and surrounding watershed became 

more productive. Sediment and nutrients from the developing 

vegetation in the watershed were transported to Onondaga Lake 

by means of the drainage network. Together with the increasing 

temperatures and a longer growing season, the sediment and 

nutrients provided lake algae with ideal conditions for enhanced 

growth. The productivity of the lake was at a maximum level 

between Cal BP 6,000 and 4,000 years ago (fig. 3).

Sedimentation rates were relatively low closer to 

Onondaga Lake in what appears to have been a transitional 

dry, to wetland, to near-shore environment. The low gradient 

of Onondaga Creek caused, in part, by (1) post-glacial uplift, 

(2) the meandering nature of a stream on the flat valley floor, 

and (3) rising Onondaga Lake water levels also affected where 

and when sediment would be deposited in this transitional 

lakeshore environment.

The low gradient of Onondaga Creek also may have 

decreased the amount of sediment and nutrients that were 

delivered to the lake as reflected in the decrease in algal growth 

in the lake beginning Cal BP 4,000 years ago (fig. 3). These 

decreases in nutrients that algae require to grow efficiently, 

together with cooler global temperatures during this period, 

would have further reduced algal growth.

Finally, the deposition rates of mostly fine-grained 

sediment on the floor of Onondaga Lake were influenced by 

the ability of Onondaga Creek and the other tributary streams 

(Ley Creek, Harbor Brook, and Ninemile Creek) to transport 

sediment from the maturing watershed to the lake. Organic 

material in the watershed was carried from the uplands to 

accumulate in the nearshore environments and left age-date 

markers in the form of organic-rich sediment. The declining 

sedimentation rate recorded in the lakebed sediments at 

various depths and locations in Onondaga Lake also supports 

the concept of a maturing ecosystem in the Onondaga Trough 

during the past 12,000 years (Cal BP 14,000 years).

By William M. Kappel and Mark A. Teece1

1

 State University of New York, College of Environmental Science and 

Forestry, Syracuse, NY.
Selected References

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matter in calcareous sediments and sedimentary rocks by loss 

on ignition—Comparison with other methods: Journal of 

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implications of Holocene lake-level fluctuations, Owasco 

Lake, New York: Geology, v. 24, no. 6, p. 519–522.

Guiles Ellis, K., Mullins, H.T., Patterson, W.P., 2004, Deglacial 

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climate change in the northeastern United States inferred 

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valley-fill aquifer in the Onondaga Trough, Onondaga 

County, New York: U.S. Geological Survey Scientific 

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Pair, D.L., Kappel, W.M., and Walker, M.S., 2000, History History

of landslides at the base of Bare Mountain, Tully Valley, 

Onondaga County, New York: U.S. Geological Survey Fact : U.S. Geological Survey Fact

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Pielou, E.C., 1991, After the ice age—The return of life to 

glaciated North America: Chicago Ill., The University of 

Chicago Press, 366 p.

Ridge, J.C., 2003, The last deglaciation of the northeastern 

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calibrated 14C chronology, in Cremeens, D.L. and Hart, 

J.P. (eds.), Geoarchaeology of landscapes in the glaciated 

northeast—Proceedings of a symposium held at the New 

York Natural History Conference VI: Albany, N.Y., New 

York State Museum, Bulletin 497, p. 15–45.

Rowell, H.C., 1992, Paleolimnology, sediment stratigraphy, 

and water quality history of Onondaga Lake, Syracuse, New 

York: Syracuse, N.Y., State University of New York–College 

of Environmental Science and Forestry, unpublished Ph.D. 

dissertation, 234 p.

Stuiver, M. and Reimer, P.J., 1993, Extended 14C data base 

and revised CALIB 3.0 -14C age calibration programme: 

Radiocarbon, v. 35, no. 1, p. 215–231. Revision 5.0.1 

available online at http://radiocarbon.pa.qub.ac.uk/calib/

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Marais, D.J., 1997, Whiting events: Biogenic origin due to 

the photosynthetic activity of cyanobacterial picoplankton: 

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Landslide hazards in glacial lake clays, Tully Valley, 

New York: U.S. Geological Survey Fact Sheet 013–98, 4 p. : U.S. Geological Survey Fact Sheet 013–98, 4 p.

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