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Geologic Driving Tours

Field Trips of Geologic Interest Departing from Perkins Restaurant at Shadowbrook Resort

The Geology of Shadowbrook Resort

 
Most of Shadowbrook is located on an alluvial (stream deposit) terrace on the inside of a meander bend of Tunkhannock Creek.  Looking directly south from the Dairy Bar, one sees 1900-foot Osterhout Mountain.  This is one of the hills capped by a thin layer of Huntley Mountain Formation.  All other high hills in the area are composed of older Devonian bedrock consisting of sandstones, shales, and mudstones which date back to about 375 million years ago.  Till left behind the last glacier (Late Wisconsinan) covers most of the lower areas.  Indeed, the hill upon which Perkins Restaurant sits is a till knob.

Road Log of Field Trips Departing from Perkins Restaurant at Shadowbrook Resort

bullet#1:  Shadowbrook to Sugar Hollow
bullet#2:  Salt Springs State Park via Lake Carey and Montrose
bullet#3:  Tunkhannock Viaduct (Nicholson Bridge) 

 
Interval  Mileage What to Observe
0.0 Leave Shadowbrook parking lot.  Turn right on US 6
0.4 0.4 Cross Tunkhannock Creek
0.5 0.9 On right is an abandoned gravel pit in a kame (going up the hillside from the creek).  Now used as a bluestone storage yard.
0.1 1.0 Bear left across Tunkhannock Creek, staying on US 6.
0.2 1.2 Traffic light; continue straight ahead across terraces of Tunkhannock Creek.
0.2 1.4. To the right is a distinct terrace-riser scarp separating two terrace levels, the lowest of which is alluvial.
0.3 1.7 Cross Tunkhannock Creek again.
0.1 1.8 Traffic light; turn left onto PA 29 South.  US 6 continues ahead.
0.1 1.9 Begin crossing the North Branch Susquehanna River; here the discharge rate is about 2.5x as that upstream at Great Bend, PA.  Along this reach of the river are a series of large incised meander bends.  Upstream to the right, rock ledges are visible at low water on the south bank where the river is undercutting the mountain side.
0.5 2.4 To left is a broad outwash terrace extending down stream a long way.  Here it rises 60 feet above present river level.
0.4 2.8 Traffic light at Wal-Mart.  Continue straight ahead.
0.1 2.9 Descend outwash terrace riser to broad Holocene alluvial terraces developed where Bowman Creek cuts across the outwash terraces to enter the river to the right.
0.5 3.4 To right is an abandoned gravel pit at the mouth of a buried tributary valley.  To the right of the pit and the partly disassembled house is a cascade of waterfalls on bedrock.  We are now driving upstream in the northeast-draining Bowman Creek valley.  The northeast-retreating glacier dammed a continuous series of proglacial lakes in this valley from its head at Ricketts Glen State Park to this point.  On the left are alluvial terraces.
0.5 3.9 To right is a cut in Catskill sandstone.
0.1 4.0 Cross Bowman Creek
1.0 5.0 Turn right into Sugar Hollow Diner.  END

 

Fall Brook can be seen through a lovely forest of large hemlock trees.

 

Shadowbrook to Salt Springs State Park via Lake Carey and Montrose

 
Interval  Mileage What to Observe
0.0 Leave Shadowbrook Resort.  Turn left on US 6
0.2 Cross Tunkhannock Creek
Stop sign.  Turn left on SR 1001.
To right is an abandoned gravel pit in ice-contact stratified drift.
To right is another gravel pit.
Bear sharply right up the hill.
    To the left beside the road is a large rounded, rough-textured boulder of phosphatic "calcareous breccia" derived from the Catskill Formation.
    To the right is a waterfall cascade beside a preglacial valley buried by till.  For the next 0.5 miles you are crossing a valley buried by a thick mass of till.
    Turn left onto SR 1003 and soon cross bridge over outlet from Lake Carey.  Downslope, hidden by trees, is a cascade of several waterfalls.
    Before the dam, to the left, as much as 250 feet of till fills the preglacial valley.  To left is the outlet to the lake with a 10 feet high human dam stabilizing the lake level.  There is bedrock under the dam where the postglacial drainage from the lake "caught" the east bedrock wall of the bedrock valley.  
    Before bearing left, look right and left at the track left by the 1998 tornado.  Turn left over the causeway along a line of till knobs, or a "morainic loop" across the valley that nearly divides Lake Carey into two separate lakes.
Stop sign.  Continue straight ahead.
Turn right on PA 29 North.
    To right is a better view of the expanse of Lake Carey, one of the largest lakes dammed by glacial deposits in the area.  The lake is easily visible through the track of the 1998 tornado.
    On the left is Mud Pond, its level raided by a small artificial dam.  The dam blocks a valley cut through a till knob that previously dammed the valley.
Intersection in village of Lemon.
    To right along an abandoned Lehigh Railroad grade is an old sandstone quarry that exposes a 3-foot-thick, calcareous brachiopod-coquinite.  This coquinite contains the brachiopod Cyrtospirifer disjunctus.
Cross Meshoppen Creek.
To left is a low cut exposing Catskill shale and sandstone.
To left is a cut in well-jointed Catskill sandstone.
Enter Susquehanna County.
    To left is Lake Walter, another man-made lake impounded by an obvious large earthen dam.
On left at top of hill is another cut in Catskill sandstone.
On right is a stoneyard.
    To the right an artificial pond marks the headwaters of the North Branch Meshoppen Creek.
    At the crest of the hill are massive outcrops of gray Catskill sandstone on both sides of the road.
Intersection in village of Springville.
Blinking traffic light in village of Dimock.
To left is a small new 'bluestone' quarry.
    To left is a bog drowned by the construction of a low dam, leaving a 'doughnut bog' in the middle.
To right is Woodbourne Forest & Wildlife Preserve.
    To left if the "bluestone"-cutting operation of Delaware Quarries.  The stone is trucked in from their quarries in the area.
To left is a cut in well-joined sandstone of the Catskill formation.
To left are several low cuts in well-jointed gray Catskill sandstone.
    Traffic light in Montrose, the county seat.  Almost directly ahead is the Susquehanna County Court House.  Turn right on PA 29.
Bear left at intersection of PA 29, PA 167 and PA 706, staying on PA 29.
    To right is Lake Montrose, its level raised by a man-made dam, it occupies the till-dammed basin at the head of Snake Creek.
    To right is a cut in Catskill sandstone and a small bedrock gorge.  On the left is a stone dam.  The stream in its downcutting has just "caught" the west bedrock wall of the buried headwater valley of north-draining Snake Creek.
    To right, behind the storage building complex are cuts exposing tens of feet of reddish-brown silty-matrix stony till that is typical in the area.
To left is an abandoned stone dam on Snake Creek.
Leave Bridgewater Township.
    To left is the buried preglacial valley of Fall Brook, the stream that now flows over the falls at Salt Creek State Park.
    Franklin Forks.  Turn left on SR 4008, proceed to entrance of Salt Springs State Park.
Salt Springs State Park has a number of interesting geologic including a rocky post-glacial gorge, three waterfalls, a historic salt spring, and the preserved site of an early 20th-century gas well.  Pick up a park brochure for information.

Tunkhannock Viaduct (Nicholson Bridge) 
Interval  Mileage What to Observe
0.0 Depart Shadowbrook.  Turn left on US 6.
0.2 0.2 Cross Tunkhannock Creek.
0.1 0.3 To right is Osterhout Mountain (summit elevation 1900 feet)
0.1 0.4 Esker on right paralleling road.
0.4 0.8 To left is a cut in gray Catskill sandstone.
0.3 1.1 Turn left on PA 92.
1.0 2.1 To left is a small post-glacial bedrock gorge with a waterfall cascade over a sandstone ledge in the Catskill Formation.  Just to the right of the gorge is the preglacial valley now buried by more than 100 feet of till.
1.3 3.4 Cut to left exposes gray sandstone over red mudstone in the Catskill Formation.
0.4 3.8 To right is the wide floodplain of Tunkhannock Creek.  Outwash and alluvial terraces are visible.  Much glacial material has been removed from this area by stream flow.
0.2 4.0 To left is large colluviated block of pitted grayish-red, calcareous sandstone from Catskill ledges higher on the hill.
0.4 4.4 To left are flay-lying ledges of Catskill sandstone at base of a deforested hill.  The deforestation is from the F-3 tornado of June 2, 1998 that traveled from left to right across the valley.
0.1 4.5 Descend the high outwash terrace that East Lemon is built on and cross tornado track.
0.8 5.2 To left adjacent to red building is a partly reclaimed gravel pit in glacial outwash.
0.1 5.3 Cross broad terraces of Tunkhannock Creek.  To right are Holocene alluvial terraces and to left are forested outwash terraces.
0.3 5.6 Ascend riser onto high outwash terrace.
0.2 5.8 To right is a small cemetery (relatively easy digging in the outwash!)
0.5 6.3 To left is a high cut in complexly interbedded and channelized, gray and grayish-red sandstone and shale and grayish-red mudstone of the Catskill Formation.  At the west end a thick pod of calcareous breccia/agglomerate occurs at the base of a crossbedded channel-sandstone.

Along the power line to right is an excellent view of high and low terraces along Tunkhannock Creek.  The high-terrace riser is particularly impressive.
0.7 7.0 Cross valley of Monroe Creek, incised through the Tunkhannock Creek terraces.
0.3 7.3 To left is a cut exposing gray and grayish-red Catskill strata that exhibit several features typical of the formation, including sandstone channel cutouts, calcareous breccia/agglomerate lenses, and calcareous nodules in red mudstone (paleosol concretions).
0.5 7.8 To right are broad, low alluvial terraces of Tunkhannock Creek.
0.1 7.9 To left is a stone farmhouse with a bedrock gorge and waterfall cascade behind it.  The preglacial valley buried by more than 100 feet of till is immediately to the right of the waterfall.
0.2 8.1 To left is a cut in gray Catskill sandstone.
0.2 8.3 To left is another cut n gray Catskill sandsstone.
0.5 8.8 Cross low alluvial terraces (cornfield).
0.1 8.9 To left is cut shoeing disturbed Catskill ledges and large colluviated sandstone blocks.
0.4 9.2 To left is a cut in red and olive-greet Catskill sandstone and shale (at bend in road).
0.3 9.5 Enter borough of Nicholson.
0.2 9.7 Cross Horton Brook Creek.
0.2 9.9 To left is an un-reinforced bluestone or flagstone wall that soil creep is now beginning to tilt and topple towards the road.
0.2 10.1 This part of Nicholson is built on the high outwash terrace of Tunkhannock Creek that stands about 100 feet above present creek level.
0.3 10.4 Descend riser to lower outwash terrace. Ahead is the great reinforced-concrete Tunkhannock Viaduct, commonly known as the Nicholson Bridge.  The structure was built by the Delaware, Lackawanna, and Western (DL&W) Railroad in 1912-1915.
0.1 10.5 Cross Martins (originally Martens) Creek
0.1 10.6 Ahead to the left are ruins of some of the coal pockets of the old DL&W Railroad.
0.3 10.9 Bear left to meet intersection with US 11.  Turn left (south) on US 11.
0.1 11.0 Cross Tunkhannock Creek.  Immediately on right is a safe pull-off and parking area with excellent views of the bridge.  END.  Be sure to read the description of this area found elsewhere in the website.

 

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