B5: INITIAL DEGLACIATION OF THE ADIRONDACK MOUNTAINS AND DEVELOPMENT OF THE FULTON CHAIN LAKES
G. Gordon Connally and Donald H. Cadwell
New York State Museum
Albany, New York
INTRODUCTION
The Adirondack Mountains, located in northern New York State, offer a textbook example of radial drainage. The Black River and its tributaries drain the west and southwest region of the Adirondacks (Figure 1). The Moose River is the largest tributary of the Black River and drains most of the southwest Adirondacks. The Fulton Chain is a series of eight lakes that lie along the Middle Branch of the Moose River.
One purpose of this paper is to describe five proglacial lakes that preceded the present day Fulton Chain, and neighboring Raquette Lake. A second purpose is to relate the formation of those glacier-dammed lakes to the inception of ice withdrawal from the Adirondack Mountains. The third purpose is to correct misrepresentations on the Surficial Geologic Map of New York, Adirondack Sheet (Cadwell and Pair, 1991) for which the senior author of this paper was responsible.
Fieldwork for this study was completed during the 1989 through 1992 field seasons. Fieldwork in the Adirondacks always has been frustrating because of 1) the large area, 2) the great topographic relief, 3) the limited road access, and 4) the paucity of exposures. During 1989 and 1990, under the aegis of the New York State Geological Survey, the existing road networks were covered and all major accessible exposures were examined. Most time was spent packing into wilderness areas during 2-day and 3-day trips - often finding no surficial materials exposed. Under those conditions, an implicit response model was adapted from nearby areas of New York State where almost all level features adjacent to ice-contact deposits are observed to be outwash.
It was not until preparation for oral presentations summarizing the field mapping (Connally and Cadwell, 1991; Fleisher et al., 1991) that Connally began to suspect a consistent error. Fieldwork later in 1991 confirmed the error. In the few places where Connally had observed exposures beneath horizontal topographic features, he had mapped lacustrine deposits. Yet, he inferred outwash beneath similar landforms lacking visible exposures. Each new exposure confirmed lacustrine deposition. When he realized that it was likely that he had systematically misinterpreted those features, the Adirondack Sheet was in final production. It was too late to revise the submitted work.

B5: INITIAL DEGLACIATION OF THE ADIRONDACK MOUNTAINS AND DEVELOPMENT OF THE FULTON CHAIN LAKES

1840 ft Blue Mountain delta in the woods at left.
Blue Mt. Lake is on the right; 1840 ft Blue Mountain delta in the woods at left.

Look for an arete on the right.

Delta terrace sediments exposed.

Raquette Lake is on the right
4.5 x 3.4 mi (7.3 x 5.6 km), present elevation of 1,762 ft.

STOP 1. Burke's Cabins are on the right; Burke's Marina on the left
Park where you can but, NOT in the restaurant parking lot. We will look at the sediment behind the marina buildings and then find an open space to discuss Glacial Lakes Raquette and Fulton.
Glacial Lake Raquette
The initial high level lake, at ±1840 ft, straddled the divide between upper Moose River and upper Raquette River drainage. It was centered on the present day Raquette Lake depression and is here named Glacial Lake Raquette (hereafter GLR). GLR spread southwest, up the Sucker Brook valley to beyond Shallow Lake; south into northern Eighth Lake, via Browns Tract Creek; and eastward up the Marion River to the Utowana Lake basin, as illustrated in Figure 4. The ±1840 ft delta at Blue Mountain suggests a long extension of GLR to the east, down the Rock River valley, where it must have been dammed by Hudson River ice.
Glacier ice in the northern Adirondack drainage basins became the northern border of GLR. South-graded outwash near Grass Pond, above Sargent Ponds, documents the former ice margin. The Forked Lake depression shows no evidence of GLR. Inversion ridges between Outlet Bay of Raquette Lake and western Forked Lake might have resulted from the drainage of GLR northward through or under the ice into Raquette River drainage. The ice margin probably remained banked against the eastern mountains north of the Marion River, anchored to the east at Blue Mountain. At least initially, ice remained along Blue Ridge, south of the Marion River valley.
There is sedimentary evidence of a small lake at ±1920 ft between Blue Ridge and Eighth Lake Mountain in the vicinity of Sagamore Lake. That lake might have been contemporary, but probably developed after GLR and its successor had drained. Moose River ice evidently established a margin at the south end of Eighth Lake and in the North Branch between present day Big Moose Lake and GLR. The Hudson-Champlain Lobe ice remained in the upper Hudson River drainage basin at Lake Durant, immediately east of Blue Mountain. Thus, GLR must have been completely surrounded by thick glacier ice.
Although it had a very irregular shoreline, and was barely 0.6 km wide in the Marion River valley, GLR had maximum dimensions of 28 km east-to-west and 12 km north-to-south. The eastward extension is documented by the hanging delta on Blue Mountain northeast of the hamlet of Blue Mountain Lake (Figure 2). Other deposits were observed along Sucker Brook to the west and south of Eighth Lake Mountain from Eighth Lake to the Raquette Lake Reservoir. More are concentrated near Inlet Creek, south of the Marion River, and along Boulder Brook, a second eastern tributary to Raquette Lake. Esker ridges (?) near Eldon Lake, at the east side of Raquette Lake, and ice-contact structures in the Blue Mountain Lake delta, suggest that remnant ice remained in GLR, at least initially.
Where was the outlet for GLR? Ice stood in the Lake Durant depression blocking eastern drainage and in the Forked Lake depression blocking northern drainage. Ice probably remained in Inlet Creek, up to the elevation of Sagamore Pond at 1904 ft. Inversion ridges suggest that this ice did not melt until GLR and its successor had drained. And there are no GLR features south of Eighth Lake. This leaves northward or eastward drainage into the ice; or southwestward drainage via either Eagle Creek or Sucker Brook.
Ice-contact stratified drift appears to have filled Eagle Creek up to ±1900 ft along Uncas Road. Indeed, the drift may mark the edge of Moose River ice that dammed GLR Although there may have been an early level of ±1960 ft in upper Sucker Brook, that may have drained southwest via the Cascade Lake channel, the thresholds are well above 1840 ft. Thus, it is not now possible to pinpoint a drainage threshold responsible for the level of GLR. The most likely possibility is somewhere eastward within the blocking Hudson River basin ice. It is proposed here that GLR drained eastward into or under leaky Hudson-Champlain Lobe ice where a topographic barrier served as an 1840 ft threshold. The most likely candidate is the channel south of the Stark Hills, 3 km east of Lake Durant. There is a possible threshold at ±1840 ft on Ledge Mountain south of the Stark Hills that overlooks what may be an abandoned plunge pool. Perhaps GLR waters were on their way to the subglacial Indian River channel.
Glacial Lake Fulton
Glacial Lake Raquette was succeeded by a more extensive lake at ±1805 ft. The release of 35 ft of water caused lake waters to withdraw almost entirely from Sucker Brook in the northwest. A dense concentration of boulders at Eagles Nest, north of Eagle Lake, probably represents a lag deposit formed during drainage of GLR. The new lake, here named Glacial Lake Fulton (hereafter GLF), spread eastward in the valley of Lake Durant, in the Rock River drainage basin. Inversion ridges west of Stark Hills, near Rock Lake on the Rock River, and between Ledge Mountain and Sawyer Mountain, suggest that this lake drained east like its predecessor into or beneath ice of the withdrawing Hudson-Champlain Lobe. To the south, the lake extended into the Fulton Chain, for which it is named, as far as Sixth Lake. The maximum extent is illustrated in Figure 5.
The dimensions for GLF shrank from 28 to 22 km east-to-west, but increased from 12 to 17.5 km north-to-south, compared to GLR. Stratified sand and silt deposits surround Raquette Lake at ±1805 ft. Those deposits extend eastward to the head of Utowana Lake and were observed adjacent to eastern Blue Mountain Lake. In the Fulton Chain, 1805 ft terraces were mapped between Eighth and Seventh Lakes and immediately south of Sixth Lake. They extend to the ice margin deposits in Eagle Creek that probably bounded GLR. Similar deposits at Lake Durant Camp and surrounding O'Neil Flow east of Blue Mountain document extension into the Rock River valley and upper Hudson drainage.
The northern ice border for GLF probably remained unchanged. Outwash south of Forked Lake is graded to ±1800 and ±1780 ft. Evidently it was deposited by active northern ice still in place after the demise of GLF. Ice-contact structures in deltas at "Burke's Cabins" and at the former landfill for the village of Inlet document the presence of remnant ice during establishment of this lake. To the east, Hudson-Champlain ice was beginning to withdraw and probably to disintegrate at its western margin. The withdrawal probably initiated the drawdown of 1840 ft GLR to 1805 ft resulting in GLF. To the west, ice still occupied the North Branch of the Moose River in the vicinity of Big Moose Lake. However, in the Middle Branch the ice margin withdrew southwestward through Eighth, Seventh, and Sixth Lakes. A small terrace remnant south of Fifth Lake also may represent this level. GLF waters may have been present in northern Fourth Lake, but we conclude that Fourth Lake deposits near 1805 ft probably represent southwest-flowing drainage that ended GLF. Late in the history ofGLF it probably drained into stagnant ice in the Fourth Lake basin.

Delta foreset beds may be exposed on the left.

Historic Sagamore is to the left
Historic Sagamore is to the left; to the right is the hamlet of Raquette Lake.

Eighth Lake
Eighth Lake, the highest of the Fulton chain, is on the right; 1.8 mi (2.6 km) long, present elevation 1,791 ft.

Cross an inlet to Seventh Lake
Cross an inlet to Seventh Lake; 3.1 mi (5.0 km) long, present elevation 1,789 ft.

Pryor's Sea Plane rides on right are on Seventh Lake.
Sixth Lake is the next lake seen through the trees; 0.9 mi (1.5 km) long, present elevation 1,789 ft.

Sixth Lake Road is on the right.

Fifth Lake is on the left
Fifth Lake is on the left, only 0.3 mi (0.5 km) long, present elevation 1,707 ft.

Inlet public parking lot on the left at the head of Fourth Lake.

Fourth Lake is on the left
6.0 mi (8.6 km) long, present elevation 1,707 ft.

Fourth Lake still is on the left.

Third Lake is now on the left, but is not visible
1.0 mi (1.6 km) long, present elevation 1,707 ft.

Second Lake now is on the left, but it also is not visible
0.8 (1.4 km) long, present elevation 1,707 ft.

First Lake is visible on the left
2.7 mi (4.4 km) long, present elevation 1,707 ft.

STOP 2. Present day Fulton chain and their predecessors
Here we will discuss the present day Fulton chain and their predecessors Glacial Lakes Inlet, Old Forge, and Thendara.
Glacial Lake Inlet
A ±1760 ft level is documented in the northern part of Fourth Lake and south of Fifth Lake. It is here named Glacial Lake Inlet (hereafter GLI) for the hamlet of Inlet just north of Fourth Lake. Although GLI was a relatively minor lake at 6 km by 10 km, it was an important step in the overall sequence.
East of the Raquette River/Hudson River drainage divide, the Hudson-Champlain ice withdrew farther eastward. GLF waters fell to a new threshold elevation at ±1790 ft and then drained altogether down the Rock River. No distinct features were observed at that elevation surrounding Raquette Lake. Thus, northern drainage of GLF to the Raquette River probably followed immediately via the Outlet Bay inversion ridge channels. That would have lowered the water level in the Raquette Lake depression to its present level of 1762 ft. South of the Raquette River/Moose River drainage divide, southwestward drainage must have commenced into or onto Moose River ice. The north portion of the Middle Branch became ice-free enabling Eighth Lake to reach its stable level at 1791 ft, Seventh Lake to reach 1786 ft, and Sixth Lake to reach ±1773 ft. Miller (1917, p. 70) stated that "From ... Raquette Lake ... preglacial drainage was almost certainly southwestward by way of ... the Fulton Chain ... ". Evidently, just the reverse was true. Seventh and Eighth Lakes, without Lake Fulton lacustrine deposits at ±1805 ft at their northern ends, probably were tributaries to the Raquette River, via the Raquette Lake depression.
In the Moose River basin, ice evidently remained in the South Branch. But a lake developed at ±1800 ft across the Dart Lake and Moss Lake depressions in the upper North Branch. It is marked by very thick deposits of lacustrine sand. The lake extended to the vicinity of Safford Pond and we here name that lake Glacial Lake Safford. The northern margin of Fourth Lake ice must have been just west of Bubb Lake, then north of Lake Rondaxe to southeast of Safford Pond. It acted as a dam for both Lake Safford in the North Branch and GLI in the Middle Branch as illustrated in Figure 6. We posit that Lake Safford gradually emptied into the Middle Branch at the hamlet of Thendara, either into the ice or over it, bypassing GLI.
Above Glacial Lake Safford another lake developed at ±1900 ft from Lake Big Moose northeastward to the drainage divide. That lake, here named Glacial Lake Big Moose, might have developed prior to Lake Safford or contemporaneously. But because overflow deposits from Big Moose Lake appear to be graded to previously deposited Lake Safford sands, we infer that it was subsequent. In any case, the combined waters of Lakes Big Moose and Safford eventually extended Lake Safford down the North Branch to a threshold at Thendara. Drainage into Moose River ice probably caused retreat of the Fourth Lake ice margin to the North Branch/Middle Branch confluence, initiating the succeeding lake.
Because of the lack of sediment downstream in the Moose River, we conclude that superglacial drainage sluiced water and sediment from the central Adirondacks into the Black River Valley. The draining of Glacial Lake Safford and Glacial Lake Inlet initiated large scale sediment bypassing as a process in the Moose River drainage basin. Bypassing was previously proposed by Connally and Cadwell (1991).
Glacial Lake Old Forge
The retreat of Moose River ice to Thendara was accompanied by a lowering water level along the Middle Branch from ±1760 to ±1740 ft. Lake Safford and Lake Inlet drained completely. The 1740 ft level is here named Glacial Lake Old Forge (hereafter GLO) for the former Browns Tract Forge and the village of Old Forge. GLO extended 20 km from Fifth Lake to the ice dam at Thendara as illustrated in Figure 7. GLO and it successor were only ±1 km wide in the Middle Branch of the Moose River and even narrower in the North Branch. Boulder deposits immediately above GLO deposits south of Fourth Lake suggest that the lowering from GLI to GLO was accomplished by strong current action. It might have been catastrophic.
Ice must have remained in the valley of Nicks Creek, to the southeast, because no 1740 ft features were observed there. However, GLO did extend up the North Branch to the vicinity of Rondaxe Lake. GLO terraces are the dominant features surrounding all of the lower lakes of the Fulton Chain. They were particularly well exposed in 1990 at the Old Forge airport. Again, drainage must have escaped southward, sluicing water and sediment through superglacial channels to the Black River Valley.
Glacial Lake Thendara
Evidence for the final pre-Fulton Chain lake is preserved at ±1720 ft. The Moose River ice margin retreated 1 km southwest and later another 6 km to Flatrock Mountain. The lowest level is here named Glacial Lake Thendara (hereafter GLT) for the hamlet of Thendara. It was ±27 km long from Fifth Lake to the ice dam as illustrated in Figure 8. GLT left low terraces from 10 to 14 ft high at many points along the lower Fulton Chain. However, GLT deposits are much more prominent along the Moose River southwest of Old Forge and in the valley of Nicks Creek. At the mouth of the North Branch, west of Old Forge, the Thendara Flats were deposited.
Drainage from GLT, like its predecessors, must have been southwest over decaying Moose River ice. Connally was able to identify the probable outlet channel, at least for GLT, in a gravel pit southwest of Thendara. A linear concentration of huge boulders that strongly suggests catastrophic drainage by very swift currents was uncovered in the autumn of 2002. These boulders are illustrated in Figure 9.
The relationship between the five proglacial lakes of the Fulton Chain, and Raquette Lake, and the natural elevations of the nine lakes are illustrated in Figure 10. The elevations, dimensions, and boundaries for those lakes are summarized in Table 2.

1740 ft lake terrace of Glacial Lake Old Forge
Rise up the scarp to the 1740 ft lake terrace of Glacial Lake Old Forge lacustrine sand.

STOP 3. Sands of Lake Thendara
STOP 3. Park where you can, then cross the bridge over the Moose River to view the sands of Lake Thendara.

1740 ft terrace deposited in Lake Old Forge.
The hamlet of Old Forge is constructed on the 1740 ft terrace deposited in Lake Old Forge.

Descend to the 1720 ft terrace deposited in Lake Thendara.

Exposure of channel deposit of boulders on the left

STOP 4. Park where you can.
We will look at ice-contact lacustrine sediments, and extremely coarse channel deposits. Then we will discuss the history recorded here. On the way out, visit the outlet channel deposits for Glacial Lake Thendara (and perhaps Lake Old Forge, and even Lake Inlet before it) in the original sand pit on the left. Note the size of the "sediment" and speculate on the rate of flow as the lake(s) drained.