Minnesota Spring Inventory

While working on something else recently, I stumbled on the Minnesota Spring Inventory. More importantly, especially in terms of time consumption, the inventory also has a great interactive map.

See any patterns?

You can zoom and select any point, or if you are interested in a particularly named spring you can type the name in the search bar to find it. Clicking on a point gives a pop-up box with information about the spring, and sometimes there are one or more links to photos.

For example, this is Big Spring at Beaver Creek State Park.

Incidentally, it looks like this. Highly recommended!

If you're curious about what the various data fields are measuring, the rules and guidelines used for documenting Minnesota springs are in this document.

If you're curious about natural or human features, there's a lot of interest to be had playing around with the map. Why human features? Springs that flow reliably and with a significant volume are great places to live, especially in the days before municipal waterworks, and many of these are of archeological and historical interest. For example, fooling around in the Minnesota River Valley area, I stumbled on one called Sacred Heart Geyser with this note: "Water was bottled and shipped to Chicago about 1900."

Obviously springs are significant natural features as well, but not only as just springs. At a glance at the map, for example, it's very easy to pick out the karst terrain of Minnesota. They can also be used as proxies for geological horizons. Springs form where groundwater isn't moving down, but laterally out of a surface. One of the biggest reasons why groundwater isn't moving down is because the flow is interrupted by a change in lithology. Maybe there's porous sandstone over non-porous shale, or limestone with fractures over shale, or pretty much anything over shale. Groundwater hits the non-permeable surface and spreads laterally, and if it runs into open air before it finds a path downward, a spring may form. (Or just a seep, which is more diffuse and less powerful.) As noted in the document, there are several geological contacts that are prone to this in Minnesota, such as glacial drift over the Decorah Shale and the Magnolia Member of the Platteville over the more shaley Hidden Falls Member. Many of the springs in Minneapolis and St. Paul are probably at one of these two contacts. (Less scientifically, springs in some settings will be found with exposed bedrock, and anywhere you've got exposed bedrock and flowing springs has a good chance of interesting geological and scenic viewing...*)

(*as always, land ownership restrictions and common sense about terrain awareness apply)