The Wellness Esker of St. Croix Falls EarthCache

To Anyone Else, It's Just A Really Big Hill A glacial treasure lies in the heart of St. Croix Falls, Wisconsin. The Wellness Esker is one of the highest eskers in the state of Wisconsin. At almost 40 meters (~130 feet), it towers above the city below, creating a breathtaking view of the St. Croix River valley, the surrounding bluffs, and across the state border into Minnesota. The base of Wellness Esker itself juts up against local residences and the hospital property on the west side, and practice fields for local sports teams to the east.

The Wellness Esker has been designated as part of the state wide Ice Age Trail system, connecting the frontal boundaries of the extent of the last glaciation, and is just minutes from a rare geologic wonder, Interstate Park, where the earth is permanently morphed by the catastrophic flooding of a prehistoric glacial lake.

A River Runs Through It

An esker is a fluvioglacial deposit formed inside of a glacier. The ice that is creeping across the surface of the earth becomes stagnant, and the bottom layer has possibly frozen solid to the ground. Meters up, upon on the surface, the sun and changing temperatures create melting ice with water flowing, creating channels into the ice. This flowing water carries sediment from the surface in its load, and also collect sediment as it carves downward through the ice. This material builds up along the bottom of the channel and creates a river bed of glacial deposits. As the main body of ice gradually recedes northward, the ice beneath these glacial rivers melts, depositing sediment of rocks, gravel, sand, and till, into a snake-like hump in the topography. Since it is a fluvial feature, the sediment inside the esker is rounded and sorted from being carried through the waters and bouncing off the ice, creating stratified layers of sediment.

Where It All Began

The Wellness Esker was formed during the last glaciation in the state of Wisconsin. Since glaciations tend to be named where they advance from, that period of ice movement was given the name Wisconsonian. The formation of the Wellness Esker was caused by the Grantsburg Lobe, a faster moving section of the Superior Lobe ice sheet, advancing into Wisconsin from northeast Minnesota, which caused the St. Croix River to be dammed by ice. This occurred a short 13,000 years ago. The ice sheet itself did not recede from Wisconsin until only 10,000 years ago, as it backed its way up to Canada through what is now Lake Superior. The sediment inside the glacier is composed of gray calcareous soils from the Canadian prairie and North Dakota plains. These materials were carried inside of the ice, or along the top of the sheet as the ice itself gouged through the bedrock and upper layers of these northern regions.

Hill Today, Gone Tomorrow

Some people may be at a loess as for what to do with a large reminder of the last time the area was covered in ice. For many years, the sediment has been mined for gravel to use in construction. This gravel is transported to the Twin Cities to be converted into cement for the constant building boom in that area. A hiking trail climbs the spine of the esker, providing panoramic views of the St. Croix River to the west, and the flat hummocky terrain of western Wisconsin. Slowly, the Wellness Esker is shrinking. The years of mining have stripped many layers of gravel from the area, and natural erosion from freeze thaw processes, water runoff, and human interaction are slowly removing the outermost layers of soil, and depositing them in the land beneath the esker.

I chose these parking coords because it was a very safe place to park, and it was an interesting perspective of the multiple forces slowly eroding this glacial footprint on this region. Take a moment to notice the greater degree of erosion at the site of tree roots in the wash out areas, versus the lack of erosion in the area of natural praire grasses and their extensive root structure preserving the integrity of the soil deposition.

**Huge earthscience lesson right there! Prairie grass root structures are far different from our hybrid cultivated Kentucky Blue Grass suburban lawns root structures.....

What's in your Backyard ?????!!!!

~~~EarthCache Logging Requirements~~~

Please post in an e-mail:

1. What is your elevation reading at GZ?
2. What are the average size and types of the rocks you encounter on the esker hiking trail?
3. What obvious forces are eroding this esker?

And......

4. Please upload a photo of yourself, or your gpsr at GZ, as well as any other interesting photos of the spectacular scenery of this unique Gem of Nature.

How often do you get the opportunity to stand in the footprint of a Glacier and view the beauty left in its wake...? Enjoy!