Soil in a wetland is different from the soil in upland areas.
Water changes the physical characteristics.
Luckily, you can see the differences. That means that hydric soils cannot hold much oxygen. The prolonged presence of water and the consequent lack of oxygen cause chemical reactions that change the color of the soil. The color and texture of the soil in an area can be used to identify it as hydric soil, even if it is not wet when you are there. Organic wetlands soils are those that, within at least 1.5 feet of the surface, are made mostly of the remains of plants and animals.