Friday, July 29, 2016

Trail crosses sand dunes formed in ice age

Sand dunes at Weaver Dunes Hiking Trail. Photo courtesy at MN DNR.
Weaver Dunes Hiking Trail aerial map
Day hikers can explore what in prehistoric times was the confluence of three major local rivers near modern Lake Pepin.

Today, the terrace where the Mississippi, Chippewa and Zumbro rivers once joined boasts 30-foot high sand dunes and serves as a nesting sight for hundreds of the rare Blanding’s turtle. Two portions of this sand prairie and floodplain are protected as part of the Kellogg-Weaver Dunes Scientific and Natural Area in Minnesota.

The 1.7-mile Weaver Dunes Hiking Trail heads through the dunes in the southernmost of the two units, which locally is referred to as the Weaver Dunes Preserve.

Shifting rivers
To reach the trailhead, from U.S. Hwy. 61 in Kellogg, Minn., take County Road 84 east. After leaving the village, the road heads south, passing the first unit. Turn left/east onto 605th Street; the blue address tag 60042 marks the road. The hike starts where the road runs out.

This is the stem to a lollipop trail. After veering straight north, the loop portion of the trail begins. You may go either direction on it.

Some 18,000 years ago as nearby ice age glaciers receded, meltwater flowed down the Chippewa, Zumbro and Mississippi rivers through this area, leaving behind sediment. Gradually, the sediment buildup shifted the Chippewa and Zumbro rivers’ confluence north. Then, over the next 4000 years, wind action shaped the sediment into dunes.

Today, the grass-covered sand dunes provide homes and food for a variety of creatures. Most notable among them is the rare Blanding’s turtle, which every June migrate here to build their nests. The turtles are easy to spot – and not just because of their bright yellow throat and high, dome-shaped carapace. They arrive in numbers, as about a thousand mother turtles trek a mile from nearby wetlands to lay their eggs here. Indeed, the American Museum of Natural History calls these dunes the most important site in the United States for Blanding’s turtles.

Come August through early autumn, the sand prairie is alive with turtle hatchlings. Volunteers often work to help the hatchlings cross a local road separating the sand prairie and wetlands.

Birds and cool bugs
With all of those hatchlings and bounty of fish that the wetlands and nearby rivers provide, the preserve also is a popular spot for raptors and migrating waterfowl. Every spring and fall, trumpeter swans flying in V-formation usually can be spotted overhead. Smaller grassland birds also like to nest in this Paleozoic plateau.

And there are plenty of cool bugs here too. The rare Ottoe skipper butterfly can be seen in midsummer. Frittilary butterflies and iridescent jumping spiders also are worthy looking for. And recently a previously unknown species of tiny moth was discovered here.

Local fauna also deliver a good show. Through the summer, the small pink blossoms of rough-seeded fameflowers open for just a few hours each afternoon. Yellow-fruited sedge stands out in midsummer. Come autumn, the grasses turn a brilliant red.

The Nature Conservancy acquired the Weaver Dunes Preserve in 1980 in an effort to preserve what is now Minnesota’s largest expanse of dry barrens prairie and savanna. Since then, they’ve removed most of the non-native pines and collected then spread seeds from the prairie plants in site.

Learn about trail guidebooks available in the Hittin’ the Trail series.