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Interpreting the Evidence

Mohawk Valley Aerial

  • Documents in this Activity:
  • Historical Eras:

    Expansion and Reform (1801 - 1861)

  • Thinking Skill:

    Historical Comprehension

  • Grade Level:

    Upper Elementary
    Middle School
    High School

  • Topics:

    Erie Canal

  • Primary Source Types:


  • Regions:

    Mohawk Valley
    Capital District
    New York State
    United States

  • Creator:

    NYS Archives Partnership Trust Education Team

  1. Load Photo of Mohawk Valley in Main Image Viewer

Suggested Teaching Instructions

Historical Context 



The Erie Canal and the Natural Landscape

Tom Grasso, Monroe County Community College


Natural History and human history are often intertwined, and nowhere is this relationship more evident than in the Erie Canal. New York State's underlying geology, unique landscape features, and stream drainage patterns made successful Canal construction and operation possible. Geologic events of the distant past resulted in Albany’s location west of the Appalachian Mountains. They also produced a system of streams flowing North and South, along the east-west Albany - Buffalo parallel. Glacial action during the Ice Age altered the landscape by forming lakes, rivers, and valleys with the right elevation, alignment and deposits for the siding of the future Canal.

In the colonial era, the Appalachian Mountains presented a formidable economic barrier disproportionate to their size. Although lower and rounder than the Himalayas, the Alps, or the Rocky Mountains, the Appalachians were heavily wooded and contained few passes or gaps suitable for travel by Wagon Train. As a result transport of goods and settlers from the Atlantic Seaboard across the mountains was lengthy, expensive, and torturous. By 18 15, there were still only three East-West Roads through the Appalachians in all of the United States. One of them followed the Mohawk River.

The Appalachians Eastward toward New England as they cross New York state from the south. Consequently, Albany lies west of much of the Appalachians. The Hudson River carves a North-South Corridor through the Appalachian chain at the highlands of the Hudson near West Point. The river provides direct, continuous, deep-water communication between the Atlantic Ocean at New York City and Albany. ( Technically, the Hudson river is an estuary of the sea, since it is affected by ocean tides as far north as the Albany - Troy area.)

Rising north of Albany and the Mohawk Valley are the Adirondack Mountains. These mountains are really a geologic extension of the 1 billion year old Laurentian mountains  of Quebec, Canada, part of what geologists term the Precambrian Canadian Shield. Albany’s location in a low-lying area between the Adirondacks and the Appalachians made an ideal Eastern Terminus for the Erie Canal.

The natural events that formed the Appalachian Mountains (250 million to 350 million years ago) Tilted relatively Thick layers of sedimentary rock toward the South. As a result, the edges of each rock formation coming to the surface were exposed in belts that run east and west across the central part of the state west of the Hudson Valley and south of the Adirondacks and Lake Ontario. Hard or resistant rock formations formed parallel East-West ridges called escarpments, such as the Niagara escarpment. Eventually, erosion along the soccer or weaker belts of shell developed river valleys that also run east and west. For example, the Mohawk River flows over the Utica black shell, while the Seneca River, the Clyde River, and Garnaqua (mud) Creek are restricted to the belt of shells that forms the Salina group. 

The Mohawk Valley is made even more significant by the Water Gap at Little Falls and the saddle (a ridge connecting to higher elevations) at Rome, Which is less than 450 ft in elevation. This is the lowest point on any route West to the interior of the continent to be found north of Birmingham, Alabama. Furthermore the East West Valley's provide a natural Corridor across nearly two-thirds of New York State. These Geographic elements combined to make the Erie Canal the most likely of all the proposed trans Appalachian canals to succeed. 

The glacial advances and Retreats of the last 2 million years of geologic history altered New York's landscape. The erosion and deposits left by the retreating glaciers changed the course of the lower Mohawk River and formed Cohoes Falls and the deep gorge between Schenectady (Rexford) and Cohoes (Crescent). The preglacial divide in stream drainage at Little Falls was breached and lowered. The result was the present - day Mohawk River flowing from Rome - the only eastward - flowing river in New York State. The continuous, low - elevation East-West Corridor of the Mohawk Valley greatly facilitated the building of the canal. In contrast, the Builders of the proposed Pennsylvania Mainline Canal to Pittsburgh were faced with the daunting task of crossing the full width and height of the Appalachian Highlands.

Glacial deposits on the sides and floor of the Irondequoit Valley were crucial to the construction of the Erie Canal, they permitted engineer's to vault the 70 ft deep valley by placing part of the canal on top of the glacial ridges (eskers), and then tying the portions together with artificial cell. The resulting Great Embankment allowed the Erie Canal to cross the broad Irondequoit Valley on a level and still go down hill from Lake Erie, thus maintaining the water body as a great Reservoir that would fill the canal all the way to Montezuma.

The Erie Canal was not the first Canal constructed in North America or even in the State of New York. However, it was the largest, most successful Public Works project undertaken in early 19th century America. New York's Natural History geological structures, erosion, and glaciation set the stage for this remarkable human achievement.