ENVIROTHON IISoils 1-3

Shane Wisseman

Relationship between soil formation and movement of water across the

landscape.

Exposed to the assaults of weather and time, solid rock slowly and continually crumbles and disintegrates. This weathering process produces the unconsolidated mineral material in which soil forms. On a stable landscape, soil develops and matures in this material directly above the weathering rock. On an eroding terrain, it is carried away by water and eventually flows into the sea.

Soil development may take place quicker in materials that are more permeable to water.

Relationship between soil formation and movement of water within soil.

When water moves down through the soil soluble minerals and nutrients dissolve and some dissolved materials are washed (leached) out.

When rain falls on a landscape, water begins to move downward by the force of gravity through the soil.

Steepness, shape, and length of slope are important because they influence the rate at which water flows into the soil.

Relationship between soil formation and movement of water within soil.

Water moving through the soil dissolves certain minerals and transports them into deeper layers. Some materials, especially sodium salts, gypsum, and calcium carbonate, are relatively soluble. They are removed early in the soil’s formation.

How soil characteristics are affected by water, and how to control water movement to prevent erosion and

pollution.  How topography, stream movement, and drainage are

related. On a stable landscape, soil develops and matures in this material directly above the weathering rock. On an eroding terrain, it is carried away by water and eventually flows into the sea.

Pennsylvania’s ridges and valleys are evidence of the differential rates of weathering of layers. Sandstone, the hardest and most chemically resistant sedimentary rock, forms the ridge caps. Limestone, the least resistant, forms the valleys. Shale, of intermediate resistance, underlies the slopes.

Drainage conditions are often indicated by soil color. Where drainage is poor and the soil is saturated for part of the year (usually in spring), patches of gray and orange discolorations, called mottles, appear.

The importance of wetlands and how to recognize potential wetland areas and hydric

soils.

Because of the prolonged presence of water, wetland soils are physically different from nonwetland soils.

Wetland (hydric) soils are saturated, flooded, or “ponded” long enough during the growing season to develop anaerobic conditions in upper layers. That is, wetland soil is at times so saturated with water that it cannot hold much, if any, oxygen.

The importance of wetlands

The abundance of nutrients, aquatic vegetation, and calm, shallow water makes wetlands one of the most productive environments.

During times when there is a lot of rain, large amounts of silt and other pollutants drift downstream. Runoff like this usually kills offshore reefs, and pollutes rivers and streams. But wetlands break down these pollutants. Wetlands also catch mud and dirt that flow downstream to coastal areas.