On of the largest palustrine wetlands in Pennsylvania, Montandon Marsh is located in northern Northumberland County. The primary wetlands (visible in the photo above) are believed to occupy a paleochannel of the Susquehanna River, which presently is about one-half mile to the west.

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The wetlands are home to a healthy and diverse ecosystem, abounding in a variety of plants and animals. The region is underlain by extensive valley fill deposits of the river. Several abandoned sand and gravel pits are located on the site and have been mostly flooded by groundwater to a depth of 6 to 8 feet.

Central Builders Inc. purchased the property in the late 1980s and began excavating sand and gravel. The active pit is located near the pond in the above photo, just south of route 45. Operations at this site are expected to continue for the next decade. This time, the quarry will be restored to create artificial wetlands which mimic the natural ones.

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Student Research

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Since 1980s, ecological and hydrogeomorphic studies of this wetland have been conducted by faculty and students at Bucknell University (Lewisburg, PA) and Susquehanna University (Selinsgrove, PA). Current efforts include the use of ground-penetrating radar and seismic refraction to map the subsurface geology, drilling shallow borings to collect samples of the aquifer sediments and installing monitoring wells, and monitoring the hydrology of the extraction pit.

Natural History


At the of the Pleistocene era, global temperatures began to rise and the vast ice sheets that covered northern Pennsylvania began to melt. Geologists have good evidence that the Susquehanna River was blocked by a tongue of the ice sheet at Bald Eagle Mountain near Williamsport/Muncy. A large dam was formed, flooding much of the region westward to Jersey Shore. Lake sediments have been found in the Nippenose Valley. This ice dam broke, sending cataclysmic pulses of water down the Susquehanna River. Man has not witnessed floods of these magnitude since and the magnitude and duration of them is unknown. However, they left sedimentologic evidence in the form of enormous boulders transported all the south to Harrisburg.
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For thousands of years the Susquehanna River was transporting vast quantities of sediment to the Chesapeake Bay. The channel had a braided pattern, much like the large rivers draining glaciers in Alaska or New Zealand. Gradually, as sediment supplies began to diminish, the channel assumed its wide and shallow single channel pattern it has today. A number of sediment bars or islands persist today, leading Native Americans to refer to the river as the Susquehanna" or "river of many islands"

For thousands of yearsThe Montandon region was home to native American tribes . French Huguenots discovered the area in 1687 and begin settling the region.