Saturday, January 8, 2011

The birth of Fort Defiance State Park

Estherville Rotarians Thursday learned how the unique geological formation known locally as Fort Defiance State Park formed - not recently but starting as long as 3.5 million years ago.

Gary Phillips, Iowa Lakes Community College environmental studies professor, told how repeated geological events created the deep-valleyed park populated with a variety of unique flora and fauna.

Starting 3.5 million years ago, the first retreating glaciers left glacial deposits, forming much of the current topography today.

Meanwhile, north of Windom, Minn., in the Jeffers, area, Sioux quartzite surfaced, pushing glacial waters northward from Sioux Falls, S.D., to New Ulm, Minn.

Then, between 12,000 to 15,000 years ago, glacial moraines left by the Wisconsin glacier left a pathway for the Des Moines River to divert from the Iowa Great Lakes watershed to the east, forming the deep-clefted valley that exists today.

With the west bank 300-400 feet higher in some places, strong erosion cut from the uplands toward the west fork, creating the valley for which Fort Defiance State Park is so well known.

Phillips said much later, probably the early 1830s when the state was first settled by Europeans, 80 percent of Iowa was prairie while the remaining 20 percent was forest, with virtually no forest in western Iowa.

With its unique west-east drainage, Fort Defiance was sheltered from prairie fires, unlike streams flowing to the southwest which were prone to summer fires coming with the southwesterly winds, Phillips said.

As a result, the park is home to many species unique to northwestern Iowa, such as red squirrels, flying squirrels, ferns, black maples and quaken aspen - the latter which is found no closer than northern Minnesota and Colorado.

Iowa's rapid population growth has left less than 10,000 acres of native prairie in the state, said Phillips. The land was either used intensively or else that which was set aside has had no management at all. As a result, many trees have populated the south and west sides of the park - areas which before World War II had few if any trees. Unfortunately, said Phillips, many things need to be done at the park that are beyond the DNR's resources.

A big reason for what ecologists term the "benign neglect" of the Fort Defiance ecosystem, similar to that of other parks, is that park stewards did not understand the same ecological concepts they do today.

As a result, the park is losing bur oaks and red oaks. A big question that park resource management faces, then, is whether they want to retain the species that are indigenous to the park or let nature take its course.

Phillips said anyone who wants to help with park projects can do so through the Friends of Fort Defiance.

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