Posted on 19 June 2014.
After the logging era, farmers began clearing remaining slash, cleared stumps from the land and planted crops. With visions of hope they planted. Till plains left by glaciers offered the best soils for crops.
Till plains are areas where melting glaciers left unsorted material in a gently rolling landscape. Very fine clay particles, larger silt, and sand particles were left with gravel, rock, and a few boulders mixed together. After removing residual stumps, farmers moved larger rocks to piles at the edge of fields or used them in home construction. The mix of clay, silt, and sand-sized particles provided fertile soil with good water holding capacity. Farms on those soils continue today.
Where the glacier front melted at the speed of the advancing ice sheet, unsorted material dropped in long ridges known as glacial end moraines. The end moraines have hills and valleys that are steep for farming. Such a moraine lies west of the Howard Christensen Nature Center (HCNC). West Michigan moraine ridges run north/south. Retreating glaciers melted westward into what is now Lake Michigan.
End Moraines acted like dams holding water between them and the ice sheet that was a few thousand feet thick. The temporary lake between glacier and moraine overflowed the moraine carrying rocks, gravel, sand, silt, and clay in floodwaters onto the land east of the moraine. Flowing water created a very wide river that was short in length unlike typical rivers that are long and narrow. The river may have only been a few miles long but many miles wide.
The rushing water that flowed over the moraine dropped the largest and heaviest material when water speed and volume reduced. Boulders and big rocks dropped first. Next gravel dropped as it was sorted from big rocks and the finer sands, silt and clay. Gravel deposits became choice for gravel companies to purchase because much of the sorting of crumbled rock was well underway.
As remaining water flowed east, it continued to lose volume, slowed, and dropped thick layers of sand with finer silts dropped farther east and finally clay settled. HCNC and the 6000-acre Rogue River State Game Area are mostly on the sorted sandy outwash soils. Sandy outwash soils are left where the floodwaters slowed enough to drop sorted sand.
Farmers settling those areas did not understand the importance of geological events and tried to make a living by farming sorted sands. The little organic topsoil quickly disappeared. The 1930’s drought across America pushed these farmers into bankruptcy. Those areas should not have been farmed.
Hunting license fees provided funds to purchase and create the Rogue River State Game Areas. Work began restoring health to the land to support wildlife and hopefully built soil structure. Pines were planted on many sandy outwashes. Farming continued in the field north of Red Pine Interpretive Center on the sterile soil where little grew, water quickly flowed through the sand, and fertility was low. Eventually the farm failed.
In 1986 I dug a soil pit so students could observe topsoil and subsoil layers. Each pit lasted about five years before we needed a new one. A 4X4 post was placed in the ground and a pit dug east of the post. After five years I moved the pit to north of the post, then west, and finally south. The demonstration area lasted twenty years. It started with a small opening 1 by 2 feet and 18 inches deep. Periodically we needed to shave the sides and enlarge the pit for good soil profile viewing.
The soil surface humus layer was thin. Organic matter blackened topsoil beneath. Abruptly a dividing line is apparent separating the more fertile topsoil from infertile subsoil. When selecting nature niches suitable for farming and supporting a family, one should understand the role of glaciers and geology of landscape development. HCNC provides real world learning applications.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at email@example.com Ody Brook, 13010 Northland Dr, Cedar Springs, MI 49319-8433. 616-696-1753.