A5:LATE GLACIAL WATER BODIES IN THE CHAMPLAIN AND ST. LAWRENCE LOWLANDS AND THEIR PALEOCLIMATIC IMPLICATIONS
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David A. Franzi. Plattsburgh State
University, Plattsburgh, NY 12901
John A. Rayburn, Binghamton
University, Binghamton, NY 13902
Catherine H. Yansa, Michigan State
University. East Lansing. MI 48824
Peter L.K. Knuepfer
Binghamton University
Binghamton, NY 13902
INTRODUCTION
The late glacial legacy of the Champlain and St. Lawrence Lowlands and northeastern Adirondack Upland region (Figures 1 and 2) is recorded in the deposits and landforms associated with proglacial and marine water bodies that formed during deglaciation. The largest and most persistent proglacial lake in the region was Lake Vermont, which occupied the central Champlain Lowland and was dammed at its northern margin by the receding ice front (Chapman, 1937; Connally and Sirkin, 1969, 1973; Parrott and Stone, 1972; Wagner, 1972; Denny. 1974; DeSimone and LaFleur, 1985, 1986). Lake Vermont expanded northward until ice receded north of the St. Lawrence Lowland and allowed marine water to inundate the isostatically depressed St. Lawrence and Champlain Lowlands, thus forming the Champlain Sea (Chapman, 1937; Occhietti et al., 2001). Deglaciation of the region postdates deglaciation in the upper Hudson Valley (ca. 13.2 14C kaB.P.; Connally and Sirkin, 1971) and was completed prior to the Champlain Sea marine incursion (ca. 12.0 14C ka B.P. to 11.5 14C ka B.P.; Clark and Karrow, 1984; Fulton et aI., 1987; Anderson, 1988; Rodriguez, 1988; Occhiett
The chronology of lake phases in the Lake Champlain basin provides insight into the style and timing of Late Wisconsinan deglaciation, but may also provide information that is relevant to global paleoclimate studies. Broecker et a1. (1989) discussed the possibility that freshwater drainage from proglacial lakes within continental North America during the last deglaciation affected North Atlantic ocean circulation and thereby altered global climate. The Champlain Lowland occupied a strategic position during the Late Quaternary deglaciation of the northeastern United States. The north-south trending lowland served both as a source of cold meltwater and as a corridor fur the transmission of proglacial lake discharges from the Great Lakes Region to the North Atlantic. The region is also located at the juncture of two freshwater discharge routes. Discharges from Lake Vermont in the Champlain Valley and proglacial lakes in the eastern and central Great Lakes basin were initially routed southward through the Hudson Valley. Ice recession eventually opened the lower St. Lawrence Valley allowing proglacial lakes in the Champlain Valley and Great Lakes basin to drain northeastward to the Gulf of St. Lawrence. The Champlain Valley region is thus a key fur recognizing when and where large freshwater discharge events entered the North Atlantic.
On this trip we shan discuss the preliminary results of our on-going investigations of the geomorphic and stratigraphic record of the late glacial water bodies in the Champlain Lowland and the significance of meltwater outflow and through flow from the lowland to the North Atlantic during deglaciation.

ALATE GLACIAL WATER BODIES IN THE CHAMPLAIN AND ST. LAWRENCE LOWLANDS AND THEIR PALEOCLIMATIC IMPLICATIONS

Rae Brook exposure
The Rae Brook exposure lies on the east side of the small stream valley to your right. The base of the section consists of dark gray, calcareous diamicton (till). The diamicton is overlain by 1.0 to 1.3 meters of thinly laminated rhythmites, which are in turn overlain by marine clays. The faunal assemblages described by Cronin (1977,1979,1981) represent the late glacial transition from lacustrine to marine environments in the Champlain and St. Lawrence Lowlands approximately 11.6 to 12.0 14C ka. B.P. The bottom water temperatures and salinities at this time probably ranged from -2°C to 10°C and 0 to 18 ppt, respectively (Franzi and Cronin, 1988).

Low-relief marine beach ridges
Denny (1970, 1974) mapped low-relief marine beach ridges on the right (east) of Barnaby Road. The hummocky topography for the next 0.5 miles was mapped by Denny (1974) as recessional moraine.

STOP 1. COBBLESTONE HILL BEACHES. (20 minutes)
The beaches at this location were first described by Woodworth (1905a) and later by Denny (1974). The deposits consist predominantly of moderately rounded to well rounded, cobble gravel in multiple, low relief ridges or terraces that extend along the northern and eastern flanks of Cobblestone Hill at elevations between 206 and 17S meters above sea level. The highest ridges lie near the projected highest shoreline of the Upper Lake Fort Ann. Individual ridges are typically 1 to 2 meters high and 10 to 20 meters wide, and often extend laterally for more than 400 meters (Denny, 1974). The gravel is almost exclusively composed of Potsdam Sandstone that was presumably derived from the alluvial cobble to boulder gravel that composes Cobblestone Hill.
The large (0.2 to 1.4 meter diameter), angular boulders that comprise the core of Cobblestone Hill can be seen along the road a short distance above the highest beach ridge. The boulders of Cobblestone Hill represent material washed into Lake Vermont from the sandstone pavements by ice-marginal streams from the breakout of glacial Lake Iroquois (Woodworth, 1905a; Denny, 1974; Clark and Karrow, 1984; Pair et al., 1988). Reworking of these alluvial deposits by wave action with relatively little longshore transport probably formed the beach deposits (Denny, 1974).

Scarpit Road at Miner ("Million Dollar") Dam
Bear right and onto a concrete road (Scarpit Road) at Miner Dam. The Scarpit Road presents many hazards, especially for those driving it for the first time. Please drive slowly and cautiously. The road lies on the southwest flank of Cobblestone Hill following the abandoned shoreline of the former reservoir behind Miner Dam.
Miner Dam was part of a failed hydroelectric project initiated by William Miner in 1910 (Gooley, 1980). By the time of its completion in March, 1913, the concrete dam, known locally as the "Million-Dollar Dam", had a maximum height of over 10 meters and stretched more than 700 meters across the Little Chazy River valley. The design capacity of the reservoir was more than 3.S million cubic meters.
The inadequate flow of the Little Chazy River and ground water seepage through Cobblestone Hill, which formed the eastern flank of the reservoir, proved to be major design flaws for the project. A 10 to 15 cm layer of concrete grout was spread over more than 100,000 m2 along the flank of Cobblestone Hill (the Scarpit) to mitigate the seepage loss. A deep trench was excavated at the base of Cobblestone Hill behind the dam for the purpose of pouring a grout curtain to the underlying sandstone and thereby, presumably, sealing the northeastern flank of the reservoir. The dam and generating station were completed in 1913 but it took almost two years to fill the reservoir to capacity. The grouting effort was partially successful and the power generating plant began operation on January 21, 1915, more than four years from the beginning of the project (Gooley, 1980). The power plant produced electricity intermittently for seven years before mechanical problems forced the abandonment of the project.
Construction of a second dam, the Skeleton Dam (Gooley, 1980), approximately 1.5 km upstream was begun in 1920 to provide supplemental flow to the main impoundment The Skeleton Dam project, however, ended with the failure of the Miner Dam generating station and was never completed.

STOP 2. COBBLESTONE HILL ICE MARGINAL DEPOSITS. (40 minutes)
The Cobblestone Hill boulder deposits occur at two distinct elevations at this location. The upper level lies between 225 and 232 meters above sea level and may correspond to cobble and boulder deposits at a similar elevation near Bear Hollow, on the southwestern side of the Little Chazy River valley. The elevation of these deposits is close to projected elevation of the Coveville Stage if the Coveville shoreline is extended northward from where Chapman (1937) and Denny (1974) mapped the northernmost Coveville shoreline deposits in the Saranac River valley, assuming a northward isobase gradient of approximately 1.2 m/km. The lower level lies between 206 and 215 meters above sea level and corresponds to the boulder deposits observed at Stop 1. The lower level boulder deposits lie close to the elevation of the Upper Lake Fort Ann high stand shoreline (Chapman, 1937; Denny, 1970.1974).
The northeastern flank of Cobblestone Hill contains several large depressions that we interpret to be kettle holes. The northeastern ends of the kettles rise onto a broad terrace composed of beach deposits (Denny, 1970, 1974) at elevations between 201 and 204 meters above sea level. These beach deposits correspond closely to the elevation of Lower Lake Fort Ann.
We believe that these data indicate that the ice margin stood at Cobblestone Hill at the time of the Lake Iroquois breakout and that proglacial water levels in the Champlain Lowland dropped during deposition of the Cobblestone Hill boulder deposits deposition of the Cobblestone Hill boulder deposits.

Note the outcrop of Potsdam Sandstone on your left.
The largest boulders on Cobblestone Hill have long dimensions that exceed 3 m.

Entering Altona Flat Rock
The Scarpit Road makes a sharp right tum and the concrete pavement ends. The road emerges onto Altona Flat Rock within 30 meters of the tum. The transition from the northern hardwood forest on Cobblestone Hill to the jack pine barrens on Altona Flat Rock is abrupt at this location.

STOP 3. ALTONA FLAT ROCK SANDSTONE PAVEMENT AND JACK PINE BARRENS.
(20 minutes) The large areas of sandstone pavement provide habitat for some of the largest jack pine (Pinus banksiana) barrens in the eastern United States (Woehr, 1980; Reschke, 1990). Jack pine is a relatively short-lived «150 years), shade-intolerant, boreal species that maintains communities on the sandstone pavements because of its adaptations to flJ"e and ability to survive in an area with thin (or absent), nutrient-poor soils.
A large proportion of the pine barrens in northeastern New York are owned by a few public and private sector organizations. The William H. Miner Agricultural Research Institute is the largest landowner of pine barrens with almost 1000 ha (hectares) of jack and pitch pine barrens on Altona Flat Rock. New York State owns an additional 600 ha of the Altona Flat Rock barrens, approximately 100 ha of the Gadway barrens and 200 ha of pine barrens at The Gulf near Covey Hill. The Adirondack Nature Conservancy owns 222 ha of the Gadway jack pine barrens at Blackman Rock.
Plattsburgh State University and the William H. Miner Agricultural Research Institute have collaborated in research and teaching initiatives in the Altona Flat Rock pine barrens for more than 30 years. The hydrogeological equipment and instrumentation at Stops 2 and 3 are part of the Ecosystem Studies Field Laboratory (ESFL), a field station dedicated to undergraduate teaching and research in geology and environmental science. The field site offers an excellent geological. hydrological and ecological setting for illustrating the interdependence of normal processes and the effects of human activities on natural ecosystems. For the past three years the ESFL site has been the focus of the Plattsburgh Research Experiences for Undergraduates program, which is funded by the National Science Foundation and the William H. Miner Agricultural Research Institute. The reader is referred to Franzi and Adams (1993,1999) for a more detailed description of the Altona Flat Rock pine barrens and the Ecosystem Studies Field Laboratory Project.

A marine beach ridge
A marine beach ridge can be seen in the field on the right (south) near the intersection with Vassar Rd.

STOP 4. INGRAHAM ESKER AT THE KALVAITIS GRAVEL PIT. (40 minutes).
The Ingraham Esker is one of the most conspicuous glacial landforms in the northern Champlain Lowland. This pit contains esker fan deposits, such as described by Diemer (1988), and deposits resedimented by wave action in the Champlain Sea as described by Denny (1972. 1974). Most of the pit is cut into proximal to medial subaqueous fan gravel and sand. The resedimented deposits consist primarily of fossiliferous gravel that occur as dipping bedsets on the western flank of the esker. Individual beds are several centimeters to a few decimeters thick and are laterally continuous for several meters.

A gravel pit containing esker tunnel
A gravel pit containing esker tunnel and proximal subaqueous fan gravel and sand can be seen on the right (west) side of the road.

STOP 5. INGRAHAM ESKER AT ESKER ROAD. (10 minutes)
This location is the "West Pit" section of Diemer (1988), Most of the sediment consists of coarse-grained channel fill deposits. These deposits generally occur in lenticular beds that are meters thick, tens of meters wide and may be traceable for tens of meters in the flow direction (Diemer, 1988). Marine reworking of the esker deposits at this location is restricted to a thin layer (1 to 2 meter) of interbedded sand and gravel near the top of the pit.

Remains of esker to south
The esker was removed in the I-87 corridor but the ridge can be seen on the right (south) side of Stratton Hill Road east of I-87.

The esker ridge parallels Rte. 9
The esker ridge parallels Rte. 9 on the right-hand (east) side of the road. The ridge crosses the Rte 9 at 26.2 miles and continues its southward trend on the left-hand (west) side of the road.

STOP 6. MARINA SECTION AND LUNCH STOP. (80 minutes)
The bluffs along the shore of Lake Champlain extend for more than 1 km north from the former Plattsburgh Air Force Base marina. The bluffs probably contain a complete late glacial stratigraphic section, however, no single location contains all of the stratigraphic units. A massive gray diamicton lies at the base of the glacial section. The diamicton is exposed at the north end of the bluffs where it overlies striated bedrock. The upper contact is not exposed.
The base of the section near the marina consists of more than 3 m of dark gray clayey rhythmites, which were probably deposited as varves in glacial Lake Vermont. The rhythmites occur as clay and silty clay couplets that range from a few centimeters thick in the lower part of the section to thin couplets that rarely exceed a few millimeters in thickness near the top of the unit. Soft-sediment deformation structures are common. Rock and sediment clasts are distributed throughout the unit as individual clasts and in discrete layers along bedding planes. A deformed bed of medium sand that is 0 to 0.2 m thick occurs near the base of the exposed section. The lateral extent of this unit is not known. A thick reddish brown clay lamina occurs near the top of the rhythmite unit. This lamina is similar in nature and stratigraphic position to a red clay bed observed in cores taken north of Montreal, Canada (Jan Aylsworth, pers. comm.).
The rhythmites are conformably overlain by 1.5 to 2.0 m of laminated to thinly bedded fossiliferous marine mud. The mud facies coarsens upward to horizontally bedded silt and fine sand. The silt and sand unit is approximately 7 m thick and the unit coarsens upward. Individual beds range from a few centimeters to a decimeter or two thick and are generally normally graded. These deposits probably record the incursion and gradual regression of the Champlain Sea in the region.

STOP 7. AUSABLE CHASM DISCUSSION AND PHOTO OP.
(15 minutes) AuSable Chasm is one of the most unique scenic spots in the Champlain lowland. The AuSable River has carved a spectacular gorge that exposes a 135 m thickness of the Keeseville Member of the Potsdam Sandstone. The AuSable River also cuts through the upper marine delta noted in the road log, and thus, the cutting of the chasm postdates the Champlain Sea interval.

Lower Lake Fort Ann delta
Rte. 9 rises out of the AuSable River Valley and onto the surface of a delta that was built into Lower Lake Fort Ann. The delta surface elevation is approximately 156 meters above sea level.

STOP 8. KEESEVILLE INDUSTRIAL PARK EXPOSURE. (40 minutes)
The Keeseville Industrial Park section is exposed in a landslide scar on the south flank of the AuSable River. The river is deeply incised into a deltaic terrace graded to Lower Lake Fort Ann. The surface elevation of the delta surface is approximately 155 m.
A massive to crudely bedded, dark gray diamicton forms the base of the section. The diamicton is overlain by approximately 2 m of rhythmically laminated silt and clay couplets. Clay laminae are generally 1 cm or less thick and the silt laminae or beds range from about 0.5 to 4 cm thick. The silt beds are commonly internally laminated. The rhythmite section contains about 67 couplets. The rhythmite section is conformably overlain by approximately 7 m of deltaic silt and sand that coarsen upward to sand and gravel.
The sediments at Keeseville Industrial Park record ice recession from the AuSable Valley. The basal diamicton is interpreted to be a till and thus represents ice cover. The rhythmites are probably varves and thus record inundation of the lower AuSable Valley by proglacial Lake Coveville. Assuming that the entire varve sequence represents proglacial Lake Coveville and the overlying silt and sand record the drop of proglacial lake level to Upper Lake Fort Ann, then Coveville occupied the lower AuSable Valley for approximately 67 varve years before proglacial lake levels dropped to the Upper Lake Fort Ann level. The ice front may have receded about 30 km north to the Cobblestone Hill Ice margin over this time interval at an average retreat rate of approximately 0.45 km/yr.

Highlands Road offers spectacular views of Lake Champlain.
Burlington, Vermont lies directly across the lake at this point and is visible on a clear day.

A series of marine terraces lie to the left (east) side of the road.

A prominent Upper Lake Fort Ann sand and gravel spit
A prominent Upper Lake Fort Ann sand and gravel spit parallels the right (west) side of the road. Chapman (1937) identified this feature and measured its surface elevation as 161 meters above sea level.

STOP 9. LONG POND CORE. (40 minutes)
The Long Pond basin was a deep embayment in Lake Coveville. The drop to the Upper Lake Fort Ann level, however, left proglacial water levels in the Champlain Lowland below the threshold of Long Pond. The bottom sediment of Long Pond was vibracored in March, 2002. Wood obtained 1 cm above a horizon that may represent the drainage of Lake Coveville at this site yielded a date of 10.9 ± 76 14C ka B.P. (Wk - 10957). These discussions will continue at the Pok-O-MacCready Outdoor Education Center 0.5 miles (63.8 miles) west of this location where a portion of the Long Pond Core will be displayed.

Upper Lake Fort Ann delta
The Deerhead Road traverses an Upper Lake Fort Ann delta built by the North Branch of the Boquet River.

Top of a large Lake Coveville delta, The Plains
The road rises to the top of a large Lake Coveville delta, known locally as "The Plains". The "The Plains" delta was built by North Branch flow that was augmented in its early stages by outflow from proglacial lakes in the AuSable River basin to the west via the "Channel Belt" (Kemp and Alling, 1925; Diemer and Franzi, 1988).

There is a good view of "The Plains" delta to the left (south).

Channeled kame terraces
The road crosses a series of channeled kame terraces and eventually rises to the quarry.

OPTIONAL STOP 10. NYCO WOLLASTONITE QUARRY. (40 minutes)
The quarry operators have excavated deeply into ice-marginal stratified drift and diamicton on the flank of Oak Hill. The composition, stratification and texture of these deposits is highly variable. The stratified sediment probably represents sedimentation by ice-marginal streams flowing from the "Channel Belt" (Kemp and Alling, 1925) and local impoundments. The diamicton are probably till or sediment flow deposits.