A crack in the rock & a beach in the forest

By: Angie Hong - East Metro Water Resource Education Program (EMWREP)

There’s a crack in the rock and water is pouring out. Liquid crystal tumbles down over moss and ferns, tossing tiny droplets that catch and glimmer on nearby spider webs. Also, there is a beach. The sand is soft and golden and if you run your hands through it, you can almost imagine an ocean lapping against your toes. Except, there isn’t an ocean, because you are standing on a cliff (or more precisely, in a cliff) and the beach is actually a portion of the wall that used to exist before it crumbled and fell to your feet.

Crystal Spring Scientific and Natural Area (SNA) in Scandia was established just four years ago when former landowner Gregory Page worked with The Trust for Public Land and Minnesota DNR to permanently protect 38 acres of land for scientific study and public understanding, as well as to maintain unique ecological and geological features on site.

The SNA is located north of the former Tiller-Zavoral gravel mine, which is now a community solar garden. In 2018, The Trust for Public Land protected an additional 20 acres that will expand the SNA and provide better public access. It contains a high-quality red oak – basswood forest on the top of the bluff, as well as sugar maple and white pine spreading down steeps slopes and ravines. The real magic, however, is the crystalline spring that pours out of the side of a rock wall, deep in an emerald chasm.

Five hundred million years ago during the Cambrian period, this part of Minnesota was covered by a shallow sea. Over time, the sand at the bottom of this sea compressed and became sandstone. Fast forward in geologic time to 14,000 years ago and you would have found Minnesota covered by glaciers. When the ice retreated, the melt water carved channels into the soft sandstone, creating the river valleys we see today.

Not all of the glacier water flowed away into the ocean, however. Some filled shallow depressions in the landscape, creating our modern day lakes, and much of the water soaked into the ground where it still exists today in the form of freshwater aquifers. The Cambrian-Ordovician aquifer system covers portions of Minnesota, Iowa, Wisconsin, Illinois, and Missouri, and the most deeply buried portions actually contain saltwater.

Groundwater flows out of a crack in the sandstone cliff, forming a freshwater stream that flows to the St. Croix River.

Along the St. Croix Riverway, there are numerous locations where groundwater flows out of cliffs and rocks in the form of seeps and springs. At Crystal Spring SNA, a groundwater spring seeps out of the side of a cliff from between layers of Jordon sandstone. The flowing water continually undercuts the ledge, so that it carves deeper into the rock wall each year. In places, the sandstone sloughs away, leaving piles of golden soft sand. It’s a beach from an ancient ocean, perched midway up a cliff in the middle of a Minnesota forest.

The Scientific and Natural Areas Program was established by the Minnesota Legislature in 1969 as part of the state Outdoor Recreation System in order to preserve in perpetuity the state’s rarest natural resources. Five of the state’s 168 SNAs are in Washington County, including Crystal Springs (38 acres) in Scandia, Falls Creek (136 acres) in Scandia, Grey Cloud Dunes (237 acres) in Cottage Grove, Lost Valley Prairie (320 acres) north of Hastings, and St. Croix Savannah (148 acres) in Bayport.

The spring-fed stream that flows through Crystal Spring SNA is one of the highest quality streams in the Carnelian-Marine-St. Croix Watershed District. A wide variety of aquatic insects and macroinvertebrates can be found in the upper reaches of the stream, while trout and other native fish inhabit the lower reaches of the stream where it flows into the St. Croix River.

If you head out to visit Crystal Spring SNA, be sure to plan ahead and take precautions to protect this fragile habitat. There is no bathroom on site, and no maintained trails. Bring mosquito spray and wear good hiking boots or shoes. If you want bonus points, bring along a small trash bag as well to pick up bits of broken glass and litter you might find during your visit. More info at www.dnr.state.mn.us/snas.