Three Falls Forest Limestone Ledge bare bones of the upper escarpment Manlius, New York PHOTO LSpeer 2005

Three Falls Forest
Onondaga Escarpment
limestone cliffs and ledges
Sweet Road & Seneca Turnpike
Manlius, New York

Latitude: 43 00 00 N Longitude: 76 00 30 W Elevation: 620 - 780 feet USGS Topographic Quad: Manlius NYSGIS tile: Manlius_SW1

Three Falls Forest harbors unexpected treasures.

see also: Three Falls Spring Floods Ancient Forest Bluestone Mystery Spot Lime Kilns Slide Show

This fragment of forgotten forest is hidden in suburbs southeast of Syracuse, seven miles from downtown. Just west is the largest open pit mine in eastern USA: Jamesville quarry. Largely invisible and unknown, this surviving woodland shelters several magnificent features, including an Ancient Forest Cathedral in a Sinkhole Sanctuary, the Three Falls themselves, 200-year-old Lime Kiln antiquities, and outcroppings of Bluestone—jumbled piles of powder blue, ringing rocks.

topographic map Three Falls Forest Manlius, New York click to enlarge

Onondaga Escarpment
the edges of ledges

The principal feature of Three Falls Forest is easy to miss—or see only in fragments—piecemeal, in an incomplete way. A series of cliffs and ledges dominate the land. The topography is shaped by successive layers of dense Devonian limestone and dolomite. These hard ridges of resistant rock are the first lands to rise from the water-logged sands and swamps of the Ontario Lake plain. The limestone layers of these cliffs, steep slopes and low hills are the first foothills of the Alleghany Highlands of southern New York.

Together, these rocky ridges form the Onondaga Escarpment, with landforms sculptured by post-glacial meltwaters, such as hanging waterfalls and plungepool lakes.

Onondaga Escarpment Bedrock Three Falls Forest, Manlius, NY

Three Falls Forest is at the east end of the Onondaga Escarpment's most distinct section, and exposes a full range of the Onondaga and Manlius Limestone Formations. Descending from the upper escarpment north of Seneca Turnpike down the Three Falls ravine to Limestone Creek is a geological journey backward through over 100 million years of Earth's earliest evolution.

The geological history of the Onondaga Escarpment is highly relevant today, because it's about climate change—how sudden small shifts in global temperatures, polar ice caps and sea levels result in massive changes in water, weather, soil, vegetation, and life on Earth.

Onondaga Escarpment limestone outcroppings run south of Onondaga Lake, across the Finger Lakes, and beyond the Genesee River to Niagara. Onondaga Escarpment's cliffs and ridges of harder limestone and dolomite are sandwiched between softer beds of shale and sandstone. In several stretches across the Finger Lakes, the exposed edge of these limestone beds form a series—or a single line—of sheer cliffs and steep, stony slopes next to smooth limestone ledges.

Bone into Stone
layers of the land's memory

The Escarpment's upper edge is the hard layers of the 30 to 60 foot thick Onondaga Limestone Formation—strong enough to resist destruction by the continental glacier in the last Ice Age. This dense, durable stone resisted erosion by ice and water, and left its print on post-glacial topography—like raised edges in an etching.

Onondaga Limestone formed 450 to 550 million years ago in the Devonian Era in an outburst of biological life—a time when Earth's early ocean waters were warmer—or maybe it was a shallow inland sea. Certain cells specialized in using calcium—sometimes with magnesium—to make crystalline shells to protect their soft bodies. Limestone is the fossil shells and skeletons of organisms that lived and died in the ancient ocean. In death, their mineral-rich bodies were left as sediments on the ancient seafloor. These tiny fossil crystal shells were compressed and cemented into a dense, durable bedrock that is mostly calcium carbonate (CaCO₃).

Onondaga Escarpment Cliff uppermost layer of limestone Three Falls Forest, Manlius, NY PHOTO DYarrow 11/28/05

The Onondaga Limestone Formation is divided by geologists into four thinner beds, each from eight to 20 feet thick: Seneca, Moorehouse, Nedrow, Edgecliff. The chemical composition, mineral structure and industrial value of each bed varies considerably. Some is shale-like, and breaks apart easily. Others contain gypsum (magnesium sulphate: MgSO₄). Chert occurs in some layers.

The Escarpment's lower ledge is formed by the Manlius Limestone Formation, which is thicker than Onondaga Limestone—normally over 100 feet—but generally weaker, more shaley and poor quality. Geology identifies within the Manlius Formation five lesser beds: Pools Brook, Pools Brook, Jamesville, Clark Reservation, and Elmwood.

Between these two limestone groups, a thin bed of Oriskany Sandstone is sometimes found—up to five feet thick in some areas, but often absent from the geological strata. This bed of sandstone may surface in Three Falls Forest as a special feature known as Bluestone ringing rocks.

Fractures & Fissures water-worn surface of the ledge Three Falls Forest, Manlius, NY PHOTO LSpeer 2005

Three Falls Forest is at the east end of the Onondaga Escarpment's most distinct section, and exposes a full range of Onondaga and Manlius Limestone Formations. Descending from the upper escarpment north of Seneca Turnpike down the Three Falls ravine to Limestone Creek is a geological journey backward through over 100 million years of Earth's earliest evolution.

NOTICE Restricted Access These woods are privately owned. Respect the owner's stewardship of this forest: step lightly take nothing away leave no disturbance

Snowball Earth
global cooling's polar ice cap

Over one hundred thousand years ago, the most recent Ice Age began, and a continental glacier—a wall of ice over 5,000 feet high—began to slide south. Geological layers of the Escarpment were crushed, gouged and scoured by this moving mountain of glacial ice. The glacier's leading edge bulldozed mountains of sand and rock into "terminal moraines" all along its southernmost margins. This geological scrubbing continued relentlessly for about 100,000 years.

About 12,000 years ago, the last Ice Age ended as the Earth began to warm. The mile-thick continental glacier began to melt faster than it was sliding south, and the glacier's leading edge began to recede slowly north. This melting mountain exposed ice-scoured bedrock beneath, and deposited thick mantles of "glacial till"—boulders, gravel, grit, and sand transported to the edge of the ice. Along the glacier's south edge, huge rivers of melting icewater swept away soil, sand and debris, and polished exposed shelves of bedrock into rounded, smooth landforms. Cracks and seams in the limestone were etched into crevices, sinkholes and caverns. The Escarpment edge was sculptured into many unusual, if not unique, landforms by ice and water in the end of the last great Ice Age.

Limestone Cliff & Talus the upper escarpment Three Falls Forest, Manlius, NY PHOTO LSpeer 2005

Ice Mountain Meltdown
sculpture by ice and water

Rotting glacial ice gushed vast volumes of icy water, which pooled along the receding ice front in a huge lake—glacial Lake Iroquois—as large as all five current Great Lakes. This immense freshwater lake had four valleys for its waters to flow to the ocean:

southwest—Alleghany-Ohio-Mississippi

As the melting glacier's front edge receded northward, new channels were uncovered for meltwaters to flow eastward along the ice front—each at a successively lower altitude. Step by step the water levels dropped and Lake Iroquois subsided and shrank. Overall, as the glacier retreated and water levels declined, meltwater flowed west-to-east to the Mohawk-Hudson drainage. Eventually, a fifth channel opened to the northeast, which today is the St. Lawrence River, which drains all the Great Lakes.

At the upper edge of the Escarpment, outwashes of water, melting ice and grit plunged over cliffs along the north edge of the Onondaga Limestone ledge in a cataract surpassing Niagara Falls in volume, if not height. The thundering waterfalls washed away soil, gravel and softer bedrock under the limestone to scour trenches and plungepools at the base of the cliffs. Icy, grit-laden waters of this mighty river swept acres of bedrock bare and bald, scoured hard rock into deep channels and ravines, and carved Escarpment cliffs and ledges into unique geological formations found few places on Earth.

Moss and Stone elder plants in an ancient landscape Three Falls Forest, Manlius, NY PHOTO LSpeer 2005

For 10,000 years, Three Falls Forest has sheltered an undisturbed memory of this margin between eras and areas of post-glacial history. As the last Ice Age ended, this land was right on the edge as the huge wall of ice thousands of feet thick receded northward. In this crystal mountain meltdown, the south edge of the rotting ice poured out torrents of icy water.

West of these three waterfalls, the limestone escarpment forms vertical cliffs, with .

For many years, Three Falls Forest was quietly protected by a common belief in a Covenant between the Town of Manlius and quarry owner Allied Chemical for "no new and different future use of the Manlius lands, other than to leave said lands in their natural state" as a buffer between the quarry and town residents. This inaccessible

FOR MORE INFORMATION on Three Falls Forest as a community ecological resource Manlius Greenspace Coalition P.O. Box 131, Manlius, NY 13104 www.ManliusGreenspace.org Manliusgreenspace@earthlink.net

woodland retreat was a well-kept secret among neighbors. With five miles of trails to hike, jog, cross-country ski, showshoe, bird watch, and over 65 species of mosses and many ferns, Three Falls Forest was an unofficial recreation park and nature preserve for Manlius residents.

But Three Falls Forest continuation as a community greenspace is threatened. A private developer acquired the land from Allied in 1989, and recently revealed a plan to build 180 houses on the last contiguous greenspace in the Town of Manlius. A pristine common space will be chopped into private lots. Three Falls will become one lucky—and very wealthy—homeowner's personal backyard—a community resource now a private pleasure.

Outctrop & Overhang upper edge of the escarpment Three Falls Forest, Manlius, NY PHOTO LSpeer 2005

Cave under the Cliff habitat beneath the limestone Three Falls Forest, Manlius, NY PHOTO DYarrow 11/28/05

Very soon, bulldozers will flatten this unique forest—the last intact natural community in Manlius. Flowforrn glacial topography formed in ten thousand years of geological history will disappear under hard fill for building lots, lawns, driveways, and roads. Unless an intervention occurs, this unique habitat and special refuge for biodiversity will be extinct. Longstanding members of our local natural community will be evicted. In some cases, entire families will be refused their home or any place by the human community.

This imminent end to this local sylvan sanctuary mobilized residents to form the Manlius Greenspace Coalition to advocate that Three Falls Forest is a unique geological, biological and ecological resource that needs protection as a permanent Nature Preserve. Clearly, there is much here to protect, preserve and extend. Realizing they are indeed witnessing "the end of Nature" in their own community, Coalition members meet frequently to collect more information and devise a unified preservation plan.

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see also: Three Falls — Spring Floods — Ancient Forest — Escarpment Bluestones — Mystery Spot — Lime Kilns — Slide Show

The Earth Restoration & Reforestation Alliance — www.championtrees.org — updated 8/2/2005