BASH in the Muck 🌱 EarthCache

The wetlands tucked into the woods at the back of the Fulton County Fairgrounds in Wauseon, Ohio, are a living reminder of this region’s watery past. Before modern drainage systems transformed the land, much of northwestern Ohio was covered by the Great Black Swamp: a vast, glacially formed wetland with saturated soils, dense forests, and slow-moving water. Although most of the swamp was drained for farming by the late 1800s, small patches of wetland like this remain, offering a glimpse into the area’s original landscape. The soils here, shaped by constant moisture and periodic flooding, are very different from the drier, better-drained soils just a short distance away. By comparing them side by side, we can see how geology, hydrology, and vegetation interact to create distinct soil characteristics.

Directions

The posted coordinates will bring you to the wetland soil site, this is where you can observe saturated or recently saturated soil conditions. Walk slowly around this area and notice the surrounding vegetation, surface moisture, and any puddles or damp patches underfoot. Pay attention to any signs of gleying or mottling in exposed soil.

The reference waypoint marks the upland (drier) soil site, just a short distance away but with noticeably different drainage. At this location, look for differences in plant life, soil firmness, and surface dryness. Try gently scraping the surface with a stick or your shoe to see how easily it crumbles compared to the wetland soil.

At both locations, take time to compare how the plants, soil color, and ground conditions change with the drainage. These observations will help you answer the questions in the logging requirements.

Geological Background

The soils that developed here are a direct result of this long-term saturation. In wetlands, constant or frequent flooding slows the breakdown of plant material, allowing organic matter to build up. The lack of oxygen in saturated soils also changes the chemistry, causing minerals like iron to lose their reddish rust color and turn grayish or bluish, a process called gleying.

In contrast, slightly higher ground, like the farm fields just outside the wetlands, drains more easily. Soils there have better aeration, allowing organic matter to break down faster and producing colors from oxidized iron, ranging from brown to reddish hues.

By visiting both a wetland soil site and a nearby upland site, you can see how even small changes in elevation and drainage create drastically different soil profiles.
 

Why Wetlands Matters

Wetlands may seem ordinary at first glance, but they provide essential environmental benefits:

• Water Filtration: Wetland soils and plants trap and break down pollutants before they can reach rivers or groundwater.
• Flood Control: Wetlands absorb and slow stormwater runoff, reducing the risk of flooding in nearby communities.
• Habitat: Wetlands support a wide range of wildlife: amphibians, birds, mammals, and insects often rely on them for breeding and feeding.

Even when they appear dry in certain seasons, wetlands, and especially seasonal vernal pools, are critical ecosystems that require careful protection.

Key Learning Points for Wetland vs. Upland

1. Soil Color

• Wetland soils often show gleying (gray, bluish, or greenish tones) and mottling (patches of orange or red where oxygen occasionally enters).
• Upland soils have more consistent oxidized colors: browns, yellows, or reds from iron in the soil reacting with oxygen.

2. Soil Texture

• Wetland: often clayey or mucky. Clay holds water longer, making the ground sticky when wet and hard when dry.
• Upland: often loam (a balanced mix of sand, silt, and clay) that allows better drainage.

3. Moisture Levels

• Wetland: surface may be damp or saturated even during dry weather; puddles may remain after rain for days or weeks.
• Upland: water drains more quickly; soil surface feels dry between rains.

4. Vegetation Indicators

• Wetland: cattails, sedges, willows, red maples, and other water-loving plants.
• Upland: corn, soybeans, grasses, oaks, and plants that prefer well-drained conditions.

Interpreting Wetland vs. Upland Soils

Even at similar elevations, soil conditions can differ greatly depending on drainage, vegetation, and sunlight.

• Wetland soils remain saturated for long periods because water moves slowly through dense clay layers beneath the surface. The tree canopy shades the ground, keeping it cooler and reducing evaporation. Lack of oxygen leads to gleying (gray or bluish colors) and higher organic matter buildup.
• Open-field soils near the farm area, despite being at a similar height, receive full sun with no tree cover. Direct sunlight speeds evaporation and warms the soil, reducing the time it stays wet after rainfall. Less standing water means more oxygen in the soil, so organic matter breaks down faster and iron minerals oxidize, creating more uniform brown or reddish hues.
• Vegetation also plays a role: deep-rooted crops or grasses in uplands pull moisture from the soil, while wetland plants tend to have shallow, spreading roots that do little to dry the deeper layers.

In short, the differences you observe are not only about height above water table, they’re also the result of soil composition, sunlight exposure, and plant water use.

Extra Definitions

Gleying: a process in soil science where soil saturation with water leads to a reduction of iron and manganese oxides, resulting in a characteristic bluish-gray or greenish-gray color. This occurs in waterlogged, anaerobic conditions. The term originates from the Russian word "glei," meaning bluish-grey. 

Mottling: the presence of irregular patches or spots of different colors within a soil, often indicating periods of wetness or poor drainage. These color variations arise from fluctuating water levels and the resulting chemical changes in the soil.