2: GLACIAL GEOLOGY AND GEOMORPHOLOGY OF THE PASSAIC, HACKENSACK, AND LOWER HUDSON VALLEYS, NEW JERSEY AND NEW YORK
Scott D. Stanford
New Jersey Geological Survey
P.O. Box 427
Trenton, NJ 08628
Scott.Stanford@dep.state.nj.us
Introduction
The New York City area is a gateway between glaciated terrain to the north and preglacial terrain and the Atlantic Ocean to the south. The Hudson valley is one of the three principal conduits into the Atlantic for meltwater draining from interior North America. Meltwater and sediment discharges from the Hudson have been invoked as the source of glaciogenic deposits and erosional features on the New Jersey continental shelf. Freshwater outflows from glacial lakes in the Ontario basin discharged down the Hudson during the late Wisconsinan deglaciation. Those outflows may have triggered the Younger Dryas and earlier climate coolings by suppressing ocean circulation in the North Atlantic (Donnelly and others, 2005; Rayburn and others, 2007; Obbink and others, 2010). More locally, glacial deposits are productive aquifers in places. Their strength properties and permeability are important features to consider when engineering infrastructure and foundations, modeling groundwater flow, and remediating groundwater and soil contamination.
Deposits of at least three glaciations are present in the New York City area. The earliest glaciation, known as the pre-Illinoian, may have occurred in the late Pliocene, between 2 and 2.5 Ma. A second glaciation is likely of late Illinoian age (∼150 ka, oxygen-isotope stage 6), although it may be somewhat older. For ease of reference, it will be referred to as the Illinoian glaciation in this paper, although an Illinoian age is not proven. The most recent glaciation is of late Wisconsinan age and reached its maximum position, as dated by radiocarbon, between 21 and 20 ka (all dates related to the late Wisconsinan glaciation are stated in radiocarbon years). Fluvial deposits south of the glacial limit, and fluvial erosional features preserved within glaciated terrain, provide evidence for preglacial and interglacial routes of the Hudson and its tributaries. This paper will survey the geomorphic and glacial history of the lower Hudson, Hackensack, and Passaic valleys in northeastern New Jersey and adjacent New York, and will discuss lake-drainage events in the upper Hudson valley that affected the lower valley and shelf during the late Wisconsinan deglaciation. A final section will discuss the glacial stratigraphy of the buried valley aquifer system in the upper Passaic basin.
The observations presented here are based on surficial geologic mapping at 1:100,000 scale in New Jersey conducted in the 1980s and early 1990s as part of a cooperative mapping program by the N. J. Geological Survey and the U. S. Geological Survey (Stone and others, 2002), and subsequent 1:24,000 quadrangle mapping by the NJGS in the 1990s and 2000s conducted in part with funding from the State map component of the National Cooperative Geologic Mapping Program, administered by the USGS. All of the quadrangles covering the New Jersey part of the study area have been mapped and published (pdfs for all maps can be viewed and downloaded at (http://www.njgeology.org/pricelst/geolmapquad.htm). These mapping efforts built on the excellent early work of R. D. Salisbury, C. E. Peet, and H. B Kummel (in Salisbury, 1895, 1902; Merrill and others, 1902; Bayley and others, 1914). Observations in New York also draw from mapping by Woodworth (1901) and Fuller (1914) on Long Island, followed by subsurface mapping conducted as part of groundwater-resource investigations in Brooklyn and Queens (Perlmutter and Geraghty, 1963; Soren, 1978; Buxton and Shernoff, 1999), and the regional map compilation of Cadwell (1989). Lacustrine and fluvial features in the upper Hudson valley discussed in the section on Lake Albany were compiled by Stanford (2010) from the works listed in the caption for fig. 6.

2: GLACIAL GEOLOGY AND GEOMORPHOLOGY OF THE PASSAIC, HACKENSACK, AND LOWER HUDSON VALLEYS, NEW JERSEY AND NEW YORK

STOP 1. The Narrows
Walk up park paths over knoll and ridge topography of the terminal moraine to the viewpoint at the bluff top of the Narrows and Verrazano Bridge.
We are standing on the late Wisconsinan terminal moraine, a 1 to 2 mile-wide (1.6 to 3 km) belt of till between 50 and 150 feet (15 and 45 m) thick, with up to 100 feet (30 m) of ridge, knoll, and basin surface relief. Ice arrived at the moraine just after 21 ka (all dates stated in radiocarbon years), and varves counted in the southern basin of Lake Passaic indicate that the ice front stayed in the moraine belt for about 750 years (Reimer, 1984). The height of the headlands here and in Brooklyn indicates that the moraine was once continuous across the mile width of the Narrows at about 50 feet (15 m) in elevation. During late Wisconsinan retreat the Narrows dam and a moraine dam across the Arthur Kill at Perth Amboy, NJ held in glacial Lake Bayonne in the Arthur Kill-Kill van Kull-New York Bay lowland. Lake Bayonne was controlled by an eroding spillway on till at the Perth Amboy dam, and gradually lowered a total of about 50 feet (15 m) as ice retreated. When the retreating ice margin uncovered Hell Gate in the East River (M1 on fig. 3), Lake Bayonne drained eastward into the Long Island Sound lowland and Hell Gate became the outlet for Lake Albany. The Hell Gate spillway is on gneiss at ∼730 feet (&sim9 m). The Hell Gate stage of Lake Albany was thus a stable lake and the shoreline, reconstructed from ice-contact deltas (text fig 6), projects to the Narrows at &sim70 feet (&sim21 m), indicating about 120 feet (36 m) of freeboard on the Narrows dam during the Hell Gate stage. The Hell Gate stage expanded northward up the Hudson valley to north of the Highlands, where delta elevations record the onset of an unstable phase of Lake Albany, with declining lake levels recording an eroding spillway (fig. 6). This indicates breaching of the Narrows dam and replacement of the stable Hell Gate spillway with an eroding spillway on moraine till. Dam breaching was caused by an outburst flood at 15.5 ka from the Augusta stage of Lake Wallkill into Lake Albany. When the north end of Schunnemunk Mountain (and Storm King in the Hudson valley) was deglaciated, the Augusta stage lowered 230 feet (70 m), releasing 6 mi³ (25 km³) of water into Lake Albany. About 40% of this volume was probably added suddenly, producing a rapid rise in Lake Albany of about 160 feet (49 m), sufficient to overtop the Narrows dam.
Dam breaching also initiated fluvial erosion of the Hudson shelf valley, which leads from the Narrows to the edge of the continental shelf. The shelf valley was subaerially exposed until about 12 ka, providing 3500 years for fluvial incision of this prominent feature.
The moraine served as the spillway for Lake Albany until ice had retreated upvalley to just south of the Albany area, where delta elevations indicate that the spillway had shifted onto the emerging lake bottom in the Newburgh area, about 60 miles (100 km) up the valley from the Narrows. During its operation, the spillway on the moraine had eroded the dam to an elevation of -200 feet (-60 m). This depth allowed the rising sea to enter the Hudson valley at about 12 ka. From 12 to 10 ka high relative sea level in the lower Hudson valley limited fluvial incision of the lake bottom in the upper valley, providing quasi-stable spillways for the Quaker Springs and Coveville stage of Lake Albany, and the upper Fort Ann stage of Lake Vermont (fig. 6).
Major lake outflows from the Ontario basin discharged down the Mohawk valley and into the Hudson during the Erie Interstade between 14.5 and 14.2 ka, when the Mohawk valley was briefly deglaciated (Ridge, 1997), and again from 12.7 to 11 ka when the Mohawk valley was the outlet for Lake Iroquois (Wall and LaFleur, 1994). These outflows exited to the shelf through the Narrows and contributed to its erosion. When the Covey Hill threshold north of the Adirondacks was deglaciated, Lake Iroquois dropped in two stages to the lower Fort Ann level of Lake Vermont in the Champlain lowland, releasing 170 mi³ (700 km³) and 600 mi³ (2500 km³) of water at 10.9 ka (Rayburn and others, 2005). These megafloods also exited through the Narrows, and may have triggered the Younger Dryas stadial in the North Atlantic region between 10 and 11 ka. They were the last glacial events to affect the Hudson valley.

Serpentinite outcrop to left in roadcut.

Salt marsh along Arthur Kill visible to right.
This is the floor of Lake Bayonne.

Enter Fresh Kills landfill, cells on both sides of 440.
Former offload dock for garbage barges to right at bridge over Fresh Kills tidal creek. Landfill now closed and garbage is exported by truck and train.

Climb onto an upland on Cretaceous deposits, veneered with till.

STOP 2. Red Bank Bluffs, Mount Loretto State Unique Area
NO SHOVELS, PICKS, OR HAMMERS
This stop requires a 1.25 mile walk along a beach and the possible fording of a shallow (ankle-deep) tidal creek. If you do not wish to do this, please remain on the bus, which will proceed 0.5 mile down Hylan Blvd. to meet us at Lemon Creek Park, at the end of the beach walk.
Walk south on driveway from parking area across the terminal moraine (fig. 9) to the beach on Raritan Bay, then walk northeastward along the beach to the parking lot for Lemon Creek Park, viewing bluff exposures along the way.
These bluffs provide an excellent exposure of the till that forms the terminal moraine. The bluffs were formed by wave erosion that has cut back about 1000 feet (300 m) into the outer edge of the moraine (fig. 9), which is estimated by fitting a smooth curve to the front of the moraine where it comes ashore to the north on Staten Island and to the west in New Jersey. The till exposed here is a compact, reddish-brown silty fine sand to silty fine-to-medium sand, containing 5-15% by volume pebbles and cobbles, and very few boulders. Pebble composition, counted on a total of 622 pebbles aggregated from five sites in the till along the bluff, is 54% red siltstone, 23% white to yellow well-rounded quartz pebbles, 13% gray siltstone and sandstone, 7% gneiss, 1% chert, and 1% purple conglomerate. The red siltstone is from the Passaic Formation in the Newark Basin. The quartz pebbles are from the Pensauken Formation, a Pliocene fluvial gravel that was widespread in the New York City area before glaciation and is locally preserved in erosional remnants beneath till on Staten Island and in adjacent New Jersey. The gray siltstone and sandstone are from gray beds in the Newark Basin and from Paleozoic sedimentary rock in the Green Pond outlier and Wallkill valley. The gneiss is from Proterozoic bedrock in the Hudson Highlands. The chert is from Paleozoic carbonate rock in the Wallkill valley. The purple conglomerate is from the Green Pond and Skunnemunk formations in the Green Pond outlier, although some may be from Newark Basin fanglomerates. The reddish matrix color is derived from erosion of the red siltstone and sandstone of the Newark Basin. Notably absent or rare are basalt, diabase, and serpentinite, all local bedrock types found within 5 to 20 miles of the bluffs. Glacial flowlines, however, show that ice moving down the Hackensack lowland to this location did not cross those lithologies (fig. 2).
Also observed in the bluff (locations 2 and 4, fig. 9) are lenses or blocks of thinly bedded white and gray silt, fine sand, and coarse sand. The lenses at location 4 are within a deformed body of glaciofluvial sand and gravel, the one at location 2 appears to be within till, although it is situated behind an old sea wall and may have been artificially emplaced. These are glacially thrust blocks of Cretaceous sand and silt of the Magothy Formation, which, along with the underlying Raritan Formation, on-laps the bedrock in the southern half of Staten island and directly underlies the till. The undeformed bedding in the thrust blocks perhaps indicates that they were frozen when glacially entrained.
The 70-foot hill is cored with light gray to pinkish-gray to very pale brown, cross bedded, clean sand and pebble-to-small cobble gravel, overlain by till. Dips on the cross-bed sets are over-steepened in places (location 3), and recumbent fold axes are also visible on the bluff face in some of the finer-grained beds, indicating that the sand and gravel has been deformed. This gravel is proglacial glaciofluvial outwash that was overrun and deformed by the advancing glacier. The deformation thickened the gravel here to form the core of the hill. Glaciofluvial plains front the moraine when it comes ashore further north on Staten Island, on Long Island, and at Perth Amboy, New Jersey. This deposit is of similar origin. Pebble composition in this unit, counted on a total of 366 pebbles aggregated from three sites in the exposure, is 41% red siltstone, 41% quartz pebbles, 13% gray siltstone and sandstone, 4% gneiss, and 1% purple conglomerate. The greater quartz-pebble content in the gravel compared to the till is from meltwater reworking of Pensauken Formation gravel that was likely widespread on the land surface in front of advancing ice.
Lenses of laminated silt and sand occur within the till at several places (locations 1 and 5). These lenses are about 20 to 50 feet long and generally less than 5 feet thick. They are approximately the same dimensions as the shallow basins on the moraine surface (visible in the meadows on the walk in) and may be swale-pond fills on the moraine surface that were later overrun by readvances as the ice front moved back and forth in the moraine belt. Again, lack of deformation suggests the fills were frozen when overrun.

Cross Mill Creek, here a tidal creek.
The head of this valley to the east (right) was an early spillway for Lake Bayonne, before it shifted to the moraine dam at Perth Amboy.

Cross the Arthur Kill.
Railroad bridge to right is the Arthur Kill lift bridge, longest center-lift bridge in the world. It was built by the B&O railroad in 1959. Piers for it and the Goethals Bridge are on red shale at a depth of 30 to 40 feet.

Bayway refinery on left.

Newark Airport to left, Port Newark to right.
Both are built on former salt marsh atop Lake Bayonne lake-bottom clays.

Rise from lake bottom onto a till on sandstone upland.

Roadcut in Orange Mountain basalt, of Lower Jurassic age.
This basalt holds up First Watchung Mountain.

Roadcut through terminal moraine (behind soundwalls).

Roadcut on right in Preakness basalt
Roadcut on right in Preakness basalt, holding up Second Watchung Mountain.

Cross Chatham-stage sluiceway
Cross Chatham-stage sluiceway, occupied by a man-made lake here.

STOP 3. Watchung Reservation. Lunch and Pre-Illinoian Till.
NO SHOVELS OR PICKS
Before lunch at the picnic area, walk down trail towards Tracy Drive to the head of a gully with a rock-gabion floor, descend the gully to view exposures of till, then exit left at bottom of gully and return uphill on adjoining gravel trail to the picnic area.
This gully is eroded into the easternmost deposit of pre-Illinoian till in New Jersey. This deposit is on the gentle dip slope of First Watchung Mountain, just outside the late Wisconsinan limit. Late Wisconsinan till (Qr on fig. 10), laid down by a brief advance beyond the terminal moraine, onlaps and overprints the pre-Illinoian till just to the north. The pre-Illinoian till here is a reddish-brown to reddish-yellow sandy clayey silt with deeply weathered to saprolitized pebbles and cobbles of red and gray siltstone, basalt, and gneiss. Gray quartzite, purple quartzite-conglomerate, black to brown chert, and well-rounded white to yellow quartz pebbles are unweathered. Large cobbles and boulders of gneiss are also intact, perhaps because the outermost weathered parts have spalled off. Fresh exposures observed in 1991 showed a thin tongue of late Wisconsinan till with lightly weathered to unweathered siltstone, gneiss, and basalt clasts overlying weathered micaceous siltstone of the Feltville Formation, at the downstream end of the gully. These materials are no longer well exposed here but can be seen in cuts along the valley side to the south. These observations show that the pre-Illinoian till rests on a gently sloping bedrock bench about 30 feet above the valley floor.
This landscape position is somewhat anomalous for pre-Illinoian till. Generally it is preserved only on flat surfaces on divides or hilltops. The anomaly is explained by the unusual history of this valley. The Blue Brook valley was deepened and widened around 21 ka because it served as the sluiceway (dotted line on fig. 10) for the Chatham stage of Lake Passaic (fig. 7). Before this incision, bedrock surface elevation contours (Stanford, 1991) indicate that this was a broad divide in the intermontane valley between First and Second mountains, with a much smaller Blue Brook draining southwestward from the divide and another small stream draining northeastward in a valley now buried by the terminal moraine and a small fronting outwash plain. The divide area was protected from erosion, preserving the pre-Illinoian till. The valley here is thus only 21,000 years old, not >800,000 years old like the other valleys in the pre-Illinoian glacial terrain. When the Hackensack lobe of the late Wisconsinan glacier blocked the Short Hills gap, the Blue Brook spillway shut down and the ice front here, no longer held at bay by the rushing lake outflow, briefly advanced into the now-empty sluice, depositing the thin tongue of till observed within the channel.

Climb up terminal moraine plugging the former Short Hills gap.

Crest of moraine in Short Hills gap.
Enter Lake Passaic basin.

Cross Passaic River, on floor of Lake Passaic.

Roadcuts for the next half mile are in lacustrine-fan deposits
Roadcuts for the next half mile are in lacustrine-fan deposits laid down in Moggy Hollow stage of Lake Passaic.

Black Meadows marsh to right, on floor of Lake Passaic.
Terminal moraine forms rise in front. Training facility for NY [sic] Jets football team to left.

Roadcut through moraine.
Roadcut through moraine. Till of the moraine hereabouts caps a section of stacked Illinoian and late Wisconsinan lacustrine sediment about 350 feet thick, one of the thickest glacial sections in NJ.

Cross under I-80.
Buried pre-intermediate Passaic-Rockaway valley here, filled with 200 feet of stacked late Wisconsinan and Illinoian till and lacustrine deposits.

Cross Rockaway River
Cross Rockaway River, redirected in postglacial time from the valley at 79.7.

Top of Boonton delta
Top of Boonton delta, deposited in Moggy Hollow stage of Lake Passaic.

Roadcut in another Moggy Hollow stage delta
Roadcut in another Moggy Hollow stage delta at Brook Valley Road overpass.

Outcrops of gneiss on left along Highland Front.

Roadcut in yet another Moggy Hollow stage delta
Roadcut in yet another Moggy Hollow stage delta, to be discussed at Stop 4.

STOP 4. Lake Passaic Fan-Delta Complex, Foothill Park, Pequannock
Walk from parking lot to the southwest corner of the park lawn, near wall of former gravel pit, to the left of the striated gneiss outcrop. When returning to parking lot, visit the outcrop, which is interlayered white, buff, and light green quartz-plagioclase gneiss and dark gray amphibolite of Middle Proterozoic age. The gneiss and amphibolite show ductile deformation and mylonitic fabric because this outcrop is very close to the Ramapo Fault, the bounding normal fault on the west edge of the Newark Basin (Volkert, 2010).
Foothill Park and the office complex to the east over to NJ 23 are within a former gravel pit. This pit was dug into a lacustrine fan deposited in the Moggy Hollow stage of Lake Passaic. The fan formerly rose as much as 50 feet above the present land surface. The excavated part of the fan is the top of a deposit more than 200 feet thick (fig. 11, section AA’), extending down to a thin basal layer of till resting on bedrock. The pit exposures, and logs of test and production wells adjacent to and within the former pit, show that the fan is pebble-to-cobble gravel and sand with some interbeds of finer sediment, for its entire thickness.
Pebble composition of the fan gravel, counted on a total of 737 pebbles aggregated from 5 sites in the former pit, is 64% gneiss, 31% gray sandstone and siltstone, and 5% purple conglomerate. Gneiss is from the Highlands, adjacent to the deposit to the north and west. Gray sandstone and siltstone are from Paleozoic rock in the Wallkill valley and Green Pond outlier to the north. Purple conglomerate is from the Green Pond outlier. Notable is the absence of red siltstone and basalt from the Newark basin, which underlies most of the fan complex and the broad lowland to the east. Ice flow during glacial advance here, as recorded by striations in the vicinity (fig. 11), including those on the outcrop in the park, was southward from the Highlands into the Newark Basin. Most ice flow from the Highlands into the Newark Basin was blocked by earlier-arriving ice of the Passaic lobe flowing southwesterly in the Basin (fig. 2), so the pattern here is somewhat anomalous. We are near the mouth of the broad, deep, south-trending Wanaque River valley that cuts the Highlands just to the north. This valley helped channel Highlands ice out into the Newark Basin in this area. The Highlands ice deposited gneiss-rich till (Netcong Till, Qn on fig. 11) on the red siltstone bedrock hereabouts. This till also contains significant amounts of gray siltstone and purple conglomerate. Subglacial meltwater feeding the fan complex during deglaciation eroded this till, and gneiss bedrock just to the north in the Wanaque valley, rather than the local red siltstone, accounting for the Highlands provenance of the fan gravel.
The northwest edge of the pit was dug into a small Moggy Hollow stage delta. This delta is now largely gutted by the I-287 cut and fill (at mile 89.9 of road log) but a fragment west of I-287 marks its original surface at about 420 feet (128 m) in elevation, indicating that Lake Passaic here was about 500 feet (152 m) deep before deposition of recessional lacustrine deposits (fig. 11, section AA’). The north wall of the pit is dug into a Great Notch stage delta with a top surface at 320 feet (97 m), visible as the tree line on the hill across the park to the north. The pit wall here shows delta foreset sand overlying pebble-to-cobble fan gravel, indicating that the delta prograded over the older fan deposit. Fan deposits laid down in the Moggy Hollow stage also crop out north of the delta (fig. 11), indicating that this delta was not deposited in contact with the glacier. Rather, as the ice front retreated northward from the fan complex toward the present position of NJ 23, an outlet channel for Lake Butler, a local lake that occupied a north-draining valley just to the west of, and higher than, Lake Passaic, was opened at the 500- foot (152 m) elevation on the hill to the west of the fan complex (arrowed line on fig. 11). At the same time, Hackensack lobe ice on the east side of the Lake Passaic basin uncovered Great Notch, and Lake Passaic lowered 80 feet (24 m) from the Moggy Hollow to the Great Notch stage. This allowed the Butler outflow to erode the north end of the Moggy Hollow delta and adjoining fans and redeposit the sediment in the Great Notch stage delta. These relationships fix the geometry of ice margin M1 (fig. 3) between Great Notch and the Highlands.
The thick, permeable fan deposits here are a prolific aquifer. Production wells for Pequannock Township (circled dots on fig. 11) are screened between 120 and 200 feet (37 and 61 m) in depth and, when first drilled, yielded between 700 and 800 gpm. The fan deposits here comprise the full thickness of the valley fill and so are unconfined, but fan gravels are more commonly buried, and confined, by lake clays (Qpml on fig. 11). Such buried, confined fan gravels are the principal valley-fill aquifers in New Jersey.

Flat plain here is top of a broad shallow-water delta
Flat plain here is top of a broad shallow-water delta deposited in the Totowa stage of Lake Passaic (fig. 7). Late Wisconsinan over-deepening in this area extends to more than 100 feet (30 m) below sea level; the over-deepening is filled with up to 300 feet (91 m) of recessional lacustrine deposits.

Climb from delta onto till hill.

Descend onto a stream terrace
Descend onto a stream terrace deposited in the Totowa stage, on top of lake clay.

Roadcut through Great Notch-stage lacustrine fan
Roadcut through Great Notch-stage lacustrine fan which was the dam for the Totowa stage.

Cross Passaic River
Cross Passaic River, much larger than before because it now includes the Pompton River.

STOP 5. Preglacial Drainage, Paterson Gap Overlook, Garrett Mountain Reservation
The Paterson gap in First Watchung Mountain is one of six paired wind gaps through the three Watchung ridges that, together with Sparkill gap in the Palisades ridge to the northeast (visible on the horizon from the overlook), define the preglacial route of the Hudson River in the Pliocene (fig. 1). These gaps are all between 1 and 1.5 mile (2 and 3 km) wide and have preglacial rock floors that decline evenly from 230 feet (70 m) at Sparkill to 180 feet (55 m) at Millburn, the southernmost gap. These rock-floor elevations are on grade with the Pensauken plain, tying them into a dated depositional chronology. This chronology indicates that, in the Pliocene before the pre-Illinoian glaciation, the Hudson was a tributary to the trunk Pensauken River that flowed southwesterly along the inner edge of the Coastal Plain, and discharged to the Atlantic across what is now the Delmarva Peninsula (fig. 1). The pre-Illinoian glacier diverted the Hudson and the Pensauken rivers to the Atlantic across western Long Island, and the gaps were abandoned. After the diversion, in the early and middle Pleistocene, the Passaic established a course that exited the Watchung crescent via the Short Hills and Millburn gaps (fig. 8A). The Illinoian glacier filled the Short Hills gap with till to a height sufficient to divert the Passaic northward through the Little Falls and Paterson gaps, which were not filled, in post-Illinoian time. The Passaic reestablished this route after the late Wisconsinan glaciation, which had further filled the Short Hills gap. Passaic Falls, a 77-foot drop over basalt in the center of Paterson, formed after the late Wisconsinan deglaciation as the river reestablished its course across a new escarpment between the resistant basalt floor of the wind gap and a glacially scoured siltstone lowland to the east. Hydropower from the falls was the original source of industrial development in Paterson, starting in 1791 with the "Society for the Establishment of Useful Manufactures" founded by Alexander Hamilton, which was one of the earliest industrial developments in the United States. The original design of water-power canals and city streets was by Pierre L’Enfant, who also designed the layout of Washington, D. C. Electricity is still generated at the falls.

Area of the Great Notch spillway, now defaced by road and railroad cuts.

Cross sluiceway
Cross sluiceway eroded by drainage of Great Notch stage around Garrett Mountain.

Descend onto flat surface of delta
Descend onto flat surface of delta deposited in Lake Delawanna, a local lake held in by a sediment dam in the lower Passaic valley.

Cross Passaic River, tidally influenced here.

Roadcuts here are in a till on sandstone upland.

Descend to the Meadowlands salt marsh
Descend to the Meadowlands salt marsh, on the floor of Lake Hackensack. A narrow, glacially over-deepened trough extending to more than 300 feet (90 m) below sea level runs along the west edge of the Meadowlands and is filled with lacustrine fan deposits overlain by lake clay.

Cross Berrys Creek, move right for exit to NJ Turnpike.
Giants Stadium on left, home to the NY [sic] Giants and NY [sic] Jets, and site of the 2014 Super Bowl.

View of Snake Hill, a diabase intrusion into siltstone
View of Snake Hill, a diabase intrusion into siltstone, to left, and landfill mountains to right, resting on salt marsh atop Lake Hackensack clays.

Cross Passaic River.
Newark to right, Pulaski Skyway to left.

Cross under Pulaski Skyway, completed in 1932.
Depth to shale bedrock ranges from 30 to 130 feet along the 4-mile length of the viaduct. Lake clay overlies the bedrock.