12,000-14,000 years ago glaciers formed moraines, hills made of sand, gravel and rock. As the ice advanced the "toe" or edge of the glacier continued to melt and deposit materials, similar to the way a conveyer belt works.
Glacial ice melted and formed several large glacial lakes, such as Agassiz and Koochiching. Water drained from Lake Koochiching and eroded Leaf Hill moraine and entered Lake Agassiz. As the fast moving water poured into Lake Agassiz, the heavier sand settled and formed a large delta.
Glacial Lake Agassiz drained northward from much of its former area. As water levels dropped, the smooth sand deltas were exposed. Weather conditions became drier and warmer than it had been, or is now. As prevailing northwesterly winds began blowing over the surface of the sand, irregularities in the surface made the wind currents move up and down, thus making the sand swirl and create ripples from the sand moving over the bumps. Ripples always form perpendicular to the directions of the wind.
As the wind moves sand along from ripple to ripple, larger irregularities form and piles of wind-blown sand become larger, forming sand dunes. Barcan dunes were the most common type of dune here when there was nothing but open sand. These form when wind moves sand up the long, low back of the dune and it sifts down the sharp, steep face, slowly building the dune up and moving it forward. Wind-blown sand also moves around the sides of the dune, moving the tails forward. Now that plants cover much of the sand, parabolic dunes are most common. The tails are held in place by the patches of vegetation covering stabilized areas.
Vegetation now covers much of the Fertile Sand Hills, but you can see examples of the exposed dunes in both Death Valley 1 and Death Valley 2. A short hike from the nature center and you can immerse yourself in ancient geological history.
The Ojibway named it "ga-papiqwutawangawi zibi", or "the river of the sand hills, scattered here and there in places." In 1800, Alexander Henry, a fur trader, passed the mouth of the river which he called the Riviere aux Buttes de Sable. This French phrase translates into English as river with hills of sand.
In 1806-07, William Henry had an outpose on the Sand Hill River. During the trading season he collected 500 beaver, 41 black bear, 1 grizzly bear (the last reported in Minnesota), 15 martens, 33 mink, 22 muskrats, 24 otters, 91 fishers, 250 wolves, 43 deer skins, 43 red fox, and 3 wolverines. He also reported an overwhelming abundance of bison, elk and waterfowl.
From 1820-1870, the Woods Trail (a major route on the Red River Oxcart Trails from Winnipeg to St. Paul) passed through this area in the general vicinity of Fertile. This route was taken to escape the Beltrami Marsh and dunes to the west, and the marshes and lakes east of Fertile. For some distance the trail followed one of the old dry beach ridges of Glacial Lake Agassiz.
A local poet, Edward Torpet, had this to say about the Sand Hill River:
The little Sand Hill s a peacable stream
It gurgles and purrs as it flows,
But at times it can swell to a mighty uproar,
And sweet away all where it goes.
The valley is wide, and it nicely contains
The floods that at times do occur,
Except to the west, where the banks overflow,
And water extends near and far.
The Sand Hill at one time gave power to two mills,
That ground up the grain into flour,
As well as a saw,ill, much south of Aldal,
That used the same river for power.
When the water was clean, and the river ran free,
And fish could come up from the Red,
The fishing was excellent, walleyes and pike,
Swam around the river's clean bed.
The Sand Hill contributes its water, at last,
To the Red, on its way to the sea,
To the icy cold waters of Hudson's grim bay,
Where the bears and icebergs run free.
In March of 2009 the Sand Hill River reached record high levels, eventually flooding up to the threshold of the building. Flooding is a natural process of the Sand Hill River. In 2009 snow melt resulted in the exceptional amount of flooding. Click on the link below to watch a short clip of the flood.
In 1976, the City of Fertile purchased 640 acres of the Sand Hills to be used as a wilderness sanctuary and recreation area. A grant in 1985 allowed the nature center building and trail system to be created. The Agassiz Environmental Learning Center (AELC) was established as a private non-profit corporation in 1991.