fluctuates. This often occurs more rapidly and to a greater 

 degree In some vertical sections of a sandy soil containing 

 high content of organic matter than in others. Thus, the sandy 

 soil appears vertically streaked with darker areas. When soil 

 from a darker area Is rubbed between the fingers, the organic 

 matter stains the fingers. 



c. Organic pans. As organic matter Is moved downward through 



sandy soils. It tends to accumulate at the point representing 

 the most commonly occurring depth to the water table. This 

 organic matter tends to become slightly cemented with aluminum, 

 forming a thin layer of hardened soil (spodlc horizon) . These 

 horizons often occur at depths of 12 to 30 Inches below the 

 mineral surface. Wet spodlc soils usually have thick dark sur- 

 face horizons that are high in organic matter with dull, gray 

 horizons above the spodlc horizon. 



CAUTION: In recently deposited sandy material (e.g. accreting sandbars) , it 



may be impossible to find any of these indicators. In such cases, consider 



this as a natural atypical situation. 



Wetland Hydrology 



Definition 



A6. The term "wetland hydrology" encompasses all hydrologlc character- 

 istics of areas that are periodically Inundated or have soils saturated to the 

 surface at some time during the growing season. Areas with evident character- 

 istics of wetland hydrology are those where the presence of water has an over- 

 riding influence on characteristics of vegetation and soils due to anaerobic 

 and reducing conditions, respectively. Such characteristics are usually 

 present in areas that are inundated or have soils that are saturated to the 

 surface for sufficient duration to develop hydric soils and support vegetation 

 typically adapted for life in periodically anaerobic soil conditions. Hydrol- 

 ogy is often the least exact of the parameters, and indicators of wetland 

 hydrology are sometimes difficult to find in the field. However, it is essen- 

 tial to establish that a wetland area is periodically inundated or has satu- 

 rated soils during the growing season. 

 Influencing factors 



A7. Numerous factors (e.g., precipitation, stratigraphy, topography, 

 soil permeability, and plant cover) influence the wetness of an area. Regard- 

 less, the characteristic common to all wetlands is the presence of an abundant 

 supply of water. The water source may be runoff from direct precipitation, 



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