B3: EXCURSION TO CLIMB MT. ARAB IN THE ADIRONDACK MOUNTAINS NEAR TUPPER LAKE
William Kirchgasser,
Department of Geology, SUNY Potsdam
kirchgwt@potsdam.edu
INTRODUCTION
The easily reached summit of Arab Mountain (Mt. Arab of trail guides), near Tupper Lake in southern St. Lawrence County, with its Fire Tower and open overlooks, offers spectacular panoramic views of the Adirondack Mountains. For geologists, naturalists and tourists of all ages and experiences, it is an accessible observatory for contemplating the geologic, biologic and cultural history of this vast wilderness exposure of the ancient crust of the North American continent.
My connection to Mt. Arab began in the 1980s on the first of several hikes to the summit in the fall season with Elizabeth (Betsy) Northrop's third grade classes from Heuvelton Central School. Although the highways and waterways in these mountains can offer breathtaking vistas, to truly experience the expanse and quiet grandure of the Adirondacks, one must climb to a summit. At two miles roundtrip on a well-maintained trail and only 760 ft. (232 m) elevation change, Mt. Arab is ranked among the easiest of the fire tower trails in New York State (Freeman, 2001); at a leisurely pace the summit at 2545 ft (176m) elevation can be reached in thirty to forty-five minutes. Mt. Arab is included in many trail guides, among them one with many useful tips on hiking with children in the Adirondacks (Rivezzi and Trithart, 1997). Through the efforts of the Friends of Mt. Arab, the Fire Tower and Observer's Cabin have been restored and there are trail guides available at the trailhead. In recent years naturalist guides are on duty during summer weekdays.

B3: EXCURSION TO CLIMB MT. ARAB IN THE ADIRONDACK MOUNTAINS NEAR TUPPER LAKE

Athletic fields: proglacial lake bottom plain (clays and silts).

Glacial-till plain (ground moraine) on left

North-facing front of proglacial-lake delta
Slope of Rte. 72 hill is north-facing front of proglacial-lake delta, the lowest of a series marking stages in the lowering of Lake Iroquois.

On right: Meander cutoff (oxbow) in Stafford Brook.

On left: Large active sand and gravel quarry
On left: Large active sand and gravel quarry in kame-moraine-delta complex. Greymont- Potsdam Stone & Concrete.

Village of Hannawa Falls.
Clean sands at top of pro glacial-lake delta (about 550 ft. elevation), marking a static level stage of Lake Iroquois.

Rte. 56 Bridge, Hannawa Falls
(Hannawa Falls Pond on left, hydroelectric dam and canal on right).

STOP 1. Potsdam Sandstone at Hannawa Falls Dam (Fig. 2)
Turn right onto Mill Street and park across the road from the Hannawa Falls Firestation Walk about 100 yards along side of road to dirt track* and follow footpath down and back towards the base of the dam.
The section here is close to the great unconformity, the boundary between the Grenville basement metamorphic gneisses of the Proterozoic Era (1.3-1.0 billion years old) and the covering sedimentary rocks of the Paleozoic Era, here in the form of the Potsdam Sandstone of Lower Cambrian (?) age. This is the type area of the the famous red Potsdam Sandstone whose age is problematic as there are no fossils (not even trace fossils) here or farther downstream in the exposures in the river and mostly abandoned stone quarries; if Lower Cambrian in age, the "time gap" at the unconformity is in the order of half a billion years. In his correlation chart, Fisher (1977) placed the lower or red Potsdam in the Lower Cambrian and assigned the underlying intermittent occurrences of arkosic conglomerates (Allens Falls/Nicholville) at the unconformity to the Late Proterozoic.
The gneisses hereabouts are typical Lowland Adirondack metamorphosed sedimentary (metasedimentary) rocks, gneisses with light-colored bands of quartz and pink orthoclase feldspar with minor dark bands of hornblende, mica and pyroxene minerals. Good exposures of these rocks may be seen in the rapids just below the dams in the Raquette River at Potsdam.
The Potsdam Sandstone exposed here, and in the rapids and side quarries downstream, display large-scale cross-bedding which indicate deposition in either a deltaic or sand dune environment (Fig. 2). Near the base of the dam on the Mill Street side, is a cylindrical structure of Potsdam Sandstone. These structures, known elsewhere in the lower Potsdam in the region, are believed to have formed from unconsolidated sands sinking into cavities lower down in the Potsdam or in the underlying Grenville basement (marbles?) (Dietrich, 1953).
The Potsdam here is a medium-bedded, fine to medium grained, silica-cemented orthoquartzite, with hematite-stained quartz grains giving the rock its distinctive red color. Its flat bedding surfaces, durability, and sets of vertical joints made the rock a valuable dimension stone and flagstone for use throughout the region in the 19th and early 20th centuries. Its limited use today is primarily as a red gravel for landscaping. In place samples of the Potsdam Sandstone can be readily obtained from exposures in the embankment on the Mill Street side of the river near the base of the dam.
The hydroelectric dam at Hannawa Falls is the 9th of 19 hydro-dams in the 167 mile length of the Raquette River between its headwaters in the Adirondacks at Blue Mountain Lake and its entry into the St. Lawrence River. The Raquette River drops some 82 feet from the dam to the powerhouse, a half-mile downstream on the east side of the river. The water at the dam is channelled to the powerhouse in a forty-foot wide, open canal, the only hydroelectric canal in the country. The Hannawa Falls powerstation, maintained by Reliant Power Corporation, generates about 50,000 mwh on average through the year.
(*Dirt track is at the south end of the 3.5 mile Red Sandstone Trail, a nature trail which leads to excellent exposures of the Potsdam Sandsone in quarries and rapids along the Raquette River).

Hannawa Pond or Flow on left.

Far left across pond: Postwood Park Town Beach.

Road climbs to flat surface at top of a delta
Road climbs to flat surface at top of a delta at about 650 ft. elevation marking another static level in proglacial Lake Iroquois.
Dunes on right are wind-blown delta sands.

County Road 24 (Brown's Bridge Road
County Road 24 (Brown's Bridge Road): left turn leads to bridge over Raquette River and trailhead parking for northern access to Stone Valley Recreational Area (see below).
Road begins climb to upper Hannawa Delta at about 680 ft. elev.

At crest of hill, view south of St. Lawrence Valley and Adk Lowlands.

Dune sands on left.

Outcrop of Grenville gneiss
Outcrop of Grenville gneiss in front of Colton-Pierrepont Central School.

Turn left to go to Stone Valley Recreational Area
Main Street Colton. Left turn and follow signs to Stone Valley Recreational Area, a 7 mile-long trail along the Raquette River which gives access to rocks of the Colton-Carthage Mylonite Zone (CCMZ).

Bridge over Raquette River: Higley Flow Reservoir.

Bog on left

Bog on right.

On left: large exposure of pink alaskitic-leucogranitic gneiss.

South Colton; dune sands on left.

STOP 2: SUNDAY ROCK, SOUTH COLTON (FIG. 3)
This huge glacial erratic boulder of Grenville gneiss was dropped by the ice-sheet that covered the North Country during Pleistocene Epoch sometime between 14,000 and 10,000 years ago. It is a legendary trail marker at the cultural boundary between the "civilized" life in the St. Lawrence Valley to the north and the rough and ready workday and recreational life in the great South Woods of the Adirondack Mountains to the south, the area where in the old days there was no Sunday. Through the efforts of the Sunday Rock Association, the boulder was moved from the center to the opposite side of the road in 1925 when Rte. 56 was first built and again to its present park location on the south side of the road in 1965 when the highway was widened. The inscription on the tablet next to the monument reads in part:
"THE TOWN OF COLTON STRADDLES THE NORTHERN BOUNDARY OF THE ADIRONDACK FOREST PRESERVE. ONE END OF THE TOWN TOUCHES ON THE NEAT HOMES OF ST. LAWRENCE COUNTY; THE OTHER REACHES INTO THE WOODS. IN THE MIDDLE IS SUNDAY ROCK.
PREVIOUS TO SETTLEMENT IN THIS AREA, THE INDIAN TRAIL INTO THE MOUNTAINS RAN BY HERE. IN THAT LONG TIME AGO THIS 64,000 POUND GLACIAL BOULDER WAS USED AS A LANDMARK BY THE INDIANS AND WHEN THE WHITE SETTLERS CAME, THEY USED IT FOR THE SAME PURPOSE. THE ROCK WAS A NATURAL LANDMARK AND TRAVELERS WERE GUIDED BY THE BIG ROCK IN THE MIDDLE OF THE ROAD, AND THE ROCK SEPARATED THE WOODS FROM THE WORLD.
THERE WAS NO LAW FOR DEER NOR TROUT, AND ALL OF THE WOODS WAS ONE GRAND HUNTING GROUND. IN THOSE DAYS, IT WAS SAID THAT BEYOND THE ROCK THERE WAS NO SUNDAY. CAMP LIFE WENT ON FROM DAY TO DAY WITH NO CHANGE. IT WAS ONE GLORIOUS HOLIDAY WHEN TUESDAY MIGHT JUST AS WELL AS BEEN SATURDAY, AND THURSDAY AND WEDNESDAY COULD CHANGE PLACES AND FRIDAY MIGHT BEGIN THE WEEK FOR ALL ANYBODY KNEW OR CARED. THE RIVERS, THE BROOKS, THE PONDS, THE MOUNTAINS, THE TREES, THE FLEET DEER, THE RUSHING TROUT, THE WILD CAT, THE BLACK BEAR RULED SUPREME. IT WAS THEIR LAND AND THERE WAS NO SUNDAY. THE ROAD PAST THE ROCK ALSO SERVED AS THE WAY FOR SCORES OF LOGGERS AND FOR THEM, THERE THE ROUGH AND TUMBLE FELLOWSHIP OF THE WINTER CAMP BEGAN. THUS THE BIG ROCK BEGAN TO BE CALLED SUNDAY ROCK. BY WHOM NOBODY KNOWS BUT THE REASON IS EVIDENT.
AFTER A WHILE, THE ROCK CAME TO STAND FOR SOMETHING ELSE. WHEN PEOPLE FROM THE VALLEY PASSED IT ON THEIR WAY TO THE MOUNTAINS, THEY FELT A SENSE OF ARRIVAL, OF HAVING CROSSED A DIVIDING LINE. ON THE OTHER SIDE OF THE ROCK WERE THE WOODS AND MOUNTAINS, LIFE WAS FREER AND EASIER. SALUTING THE ROCK BECOME A KIND OF JOYFUL RITUAL TO BE OBSERVED. ELDERS MIGHT UNCORK A BOTTLE AT IT AND CHILDREN COULD CUT UP WITHOUT FEAR OF A SCOLDING. HUNTERS AND FISHERMEN HAD THE FEELING OF EAGER ANTICIPATION AS THE CARES OF EVEYDAY LIFE WERE LEFT BEHIND ...
FOR MANY WHO PASS BY HERE, THE ADIRONDACKS STILL EXERT THEIR MYSTICAL APPEAL. VACATIONISTS WHO RETURN TO THESE HILLS YEAR AFTER YEAR, PROBABLY HAVE THEIR OWN SUNDAY ROCK: A RIVER CROSSING, A TURN IN THE ROAD THAT REVEALS A FIRST GLIMPSE OF THE MOUNTAINS, SOME SIGN THAT YOU HAVE CROSSED INTO A PLACE WHERE THE CALENDAR CAN BE FORGOTTEN, WHERE THERE IS BEAUTY TO LOVE AND THE EVERLASTING HILLS TO SAVOR.
THE MEANING OF THE ROCK HAS NOT BEEN FORGOTTEN ...IT HAS BEEN THE CONTINUED AFFECTION OF MANY GENERATIONS WHICH HAS PRESERVED THE OLD LANDMARK AND LEGEND SURROUNDING IT. SUNDAY ROCK STILL SEPARATES THE WOODS FROM THE WORLD, AND THE MESSAGE FROM THOSE WHO PRESERVED IT IS STILL CLEAR. THE WOODS ARE BETTER."
Allan Pospisil (1968) Colton Story of a Town. The New York Times. [extracted in part from an article by Potsdam Town Historian C. H. Leete in Potsdam Herald Recorder, September 11, 1925 (Sunday Rock-Its history and the story of its preservation-1929, Herald Recorder Press, Potsdam, N.Y.,55p.)]

STOP 3. GRENVILLE GNEISS BELOW SOUTH COLTON DAM
Warning: Take care not to be trapped on the outcrop by water released from the dam upstream.
These well-exposed rocks display many of the structural and textual features typical of the Grenville basement rock of the northern part of the Adirondack Highlands. The variety of gneisses and minerals, and the predominantly banded fabric, suggest an original sedimentary sequence that was metamorphosed deep within the roots of a mountain belt under the extreme conditions (granulite facies) associated with continental collision and consequent tectonic burial. Included are pyroxene and hornblende granitic gneisses with subordinate leucogranitic gneisses, amphibolites (dark colored hornblende-rich gneisses) and migmatites (mixed igneous and metamorphic rock) in which coarse pods of pegmatitic crystals of pink K-feldspar indicate partial melting during metamorphism.
Notable are the complex ductile folds and broken layers isolated as fragments or 'tectonic' xenoliths. The fold patterns and the predominant NE-SW strike of the foliation or banding are typical of the basement rocks of the region.
At low discharge, the rivelets of water flowing across the surface of the outcrop and the orientation (facing) of the waterfall is a fine example of local structural control of drainage, a microcosm of patterns seen in the Adirondacks as a whole. The broadly radial stream courses (outward from the center of the Adirondack Dome) are locally controlled by differential erosion of the banding, foliation and folding in the various metamorphic facies and the intersections of faults, joints or fractures. Other notable erosion features include potholes at various stages of development.
A hundred yards or so upstream on the west bank of the river, a tabular basalt (diabase) dike (2.3 m across) is well exposed along the shore. The dike is nearly parallel to the steeply inclined foliation or banding of the gneisses. Its dark color and uniform mineralogical texture and higher resistance to weathering contrasts with the lighter colored and banded gneisses. The dike is clearly younger than the host rock and was intruded after the gneisses were metamorphosed but before the tectonic development of the joints. The dike is probably late Proterozoic in age (around 570 Ma.), based on its similarity to pre-Potsdam dikes elsewhere in the region. At high water the dike can be reached by the dirt tract that parallels the edge of the river upstream from the waterfall.
The rock forming the hill to the south of the outcrop, which can be reached along the Allen Hill Road, is a quartz-rich granite-gneiss with prominent pink orthoclase and minor dark mineral (leucogranitic gneiss) that retains its igneous (pluton) texture, and although the contact is not exposed, it probably cross-cuts the banded gneisses at the waterfall and is thus younger than the gneisses and older than the basalt dike.

Cold Brook Drive-right turn to Higley Flow State Park.

Allen Hills Road on left: granite-gneiss outcrops at top of hill.

Caution: entering "zig-zag" in highway
Caution: entering "zig-zag" in highway (watergap cut through glacial-delta sediments by Cold Brook).

"Blue Line" Sign on right marking boundary of 6 million acre Adirondack Park.

"The Plains"-top of pro glacial-lake delta at about 1210 ft.

Joe Indian Pond Road-on left.

Bog pond on right.

"Fraternity Rock"-huge, painted glacial erratic on left.

Large bog on right.

Outcrops of Grenville gneiss on left.

Massawepie Lake-Scout Camp

Sand pit on left

Mt. Arab Fire Tower visible-straight ahead

Park on right side of road opposite signs at trailhead.

STOP 4. Mt. Arab
Introduction
The trail to Arab Mountain is approximately 1 mile (1.6 km.) long and rises 760 ft. (232 m.) to a summit elevation of 2545 ft. (776 m.). The summit is about 2115 ft. (645 meters) above the elevation of downtown Potsdam 430 ft. (131 meters).
Follow the red Department of Conservation (DEC) markers and stay on the designated trail. The restoration and maintenance of Mt. Arab is under the care of Friends of Mt. Arab, Inc. with the cooperation of the Laurentian Chapter of the Adirondack Mountain Club (ADK). Please register for your safety and help the Friends of Mt. Arab determine the frequency of trail use; the Interpretive Information Brochure in the registration box is a guide to sixteen locations of features of biological interest.
Basement rock
The gravel covering the lower part of the trail is crushed anorthosite, the blue-gray feldspar-rich rock that underlies the region of high mountainous terrane to the east, including Whiteface Mountain and the Marcy Massif of the High Peaks region. At about midway, the trail surface is mainly on mangerite, the principal bedrock of Mt. Arab. Mangerite is an intrusive or plutonic igneous rock, like a granite, but with less quartz and containing the mineral pyroxene. A few hundred yards from the summit, the mangerite bedrock is exposed in a large outcrop. The broad, subhorizontal fractures seen here and at the summit are sheeting or exfoliation structures, formed by the release of pressure on the rock by the tectonic unroofing, and uplift and erosion of overburden rock during the Proterozoic and later times, and most recently following the final melting of the mile-thick Pleistocene glacier. These fractures and the glacial scour are what account for the smooth and broadly rounded shape of many Adirondack summits.
The mangerite exposed here and at the summit is a metamorphosed igneous intrusive (plutonic) rock whose color, composition and texture contrast strongly with the variety of banded metasedimentary gneisses seen at South Colton and the intrusive anorthosites of Whiteface Mountain and the Marcy Massif to the northeast, east and southeast (Fig. I-C). The mangerite, which contains only minor quartz, consists of cream colored intergrowths of feldspars (mainly potassium feldspar) with dark mafic minerals (pyroxene) oriented subparallel to the long axes of the feldspar crystals (anastomosing, perthitic texture), giving the rock a strongly planar foliation. The contrast with banded hornblende gneisses seen at South Colton is striking. On the outcrop surfaces (west of the Observer's Cabin) sheared quartz veins (Fig. 6) give evidence of plastic (ductile) deformation and the high intensity of metamorphism (granulite facies with temperatures of 675-800 degrees C and pressures of 7-8 kilobars) in the roots of a mountain range, comparable to some 25-30 km. (17-20 miles) depth below the surface.
A Uranium (U)-lead (Pb) radiometric date on the mangerite of 1134 ± 4 million years at Tupper Lake (McLelland and Chiarenzelli, 1990) gives the time of crystallization of the magma intrusion. The mangerite in the Tupper Lake region shows a spatial relationship with the anorthosite, the great mass of plutonic rock that underlies the Whiteface Mountain region and Marcy Massif of the High Peaks region; the contact between these units is just east of Tupper Lake. The anorthosite is composed predominantly of the blue-green-gray crystals of the plagioclase feldspar andesine and the small fragments of the anorthosite can occasionally be seen "floating" in the mangerite at Mt. Arab. The age of emplacement of the anorthosite plutons is around 1155 Ma., which is close to the time of emplacement of the mangerites.
Fire Tower
The 35 foot high steel Fire Observation Tower at the summit, installed in 1918, replaced wooden structures dating from 1911 and 1912. This "survivor that still stands guard" (Laskey, 2003) is one of only two remaining fire towers in St. Lawrence County; the other is on Cathedral Rock in Wanakena (Freeman, 2001, p. 44). The network of observation towers was established after the disastrous fires in the Adirondacks in 1903 and 1908; at one time there were 57 towers in the Adirondacks. No longer in service, the Mt. Arab Tower and Observer's Cabin were last staffed in the 1980s in the final stages (accelerated during and after WWII) of the systematic dismantling of the fire tower observation system in Adirondack and Catskill Mountains. After decommission, the Mt. Arab Tower deteriorated and was condemned for public use in 1993.
The restoration of the tower and access trail dates from 1997 and the founding of the citizens's group Friends of Mt. Arab (FOMA), an organization that has coordinated endorsements and financial support from state, county and local government agencies as well as several Adirondack Mountain Club (ADK) chapters, school groups, camp owners and local residents. The Observer's Cabin has been restored as a small museum and base for a summer interpreter, thus completing the functional evolution of the tower and cabin from fire observation to education and recreation. Supported by the Adirondack Architectural Heritage (AARCH), the Friends of Mt. Arab can be contacted at P.O. Box 185, Piercefield, NY, 12973.
Adirondack Landscapes (Figs. 5-6)
Among the features that can be seen from the top of the the Fire Tower: north- northeast, Mt. Matumbla (2700 ft.; 823 m.), the highest point in St. Lawrence County; northeast, in far the distance beyond Tupper Lake and Tupper Lake Village, Whiteface Mountain (4867 ft.; 1483 m.) with its distinctive white landslide scars; southeast Mt. Morris (3163ft.; 964 m.) with its Big Tupper ski-trail clearings, and in the distance, the rounded profile of Blue Mountain (3759 ft.; 1146 m.) near the center the Adirondack Dome and the headwaters of the Raquette River; far to the east-southeast, the High Peaks, which include Algonquin Peak (5114 ft.; 1559 m.), Mount Colden (4714ft.; 1437 m.) and Mount Marcy (5344 ft.; 1629 m.), the highest point in New York State. Nearby to the southwest, Mt. Arab and Eagle Crag Lakes; and south-southeast, the south end of Tupper Lake.
With modern technology, changes in elevation and geographic position of features on the surface of the earth can be monitored remotely by satellite and laser. Attached to the bedrock on the summit are three small metal disks, the United States Geological Survey bench marks that were used in surface surveys to determine the geographic position and elevation of Arab Mountain.