{Note: See p. 59 for mollisols exception.) 



Colors should be determined in soils that 

 are or have been moistened. The chroma require- 

 ments above are for soils in a moistened condition. 

 Colors noted for dry (unmoistened) soils should be 

 clearly stated as such. The colors of the topsoil are 

 often not indicative of the hydrologic situation be- 

 cause cultivation and soil enrichment affect the 

 original soil color. Hence, the soil colors below the 

 A-horizon (usually below 10 inches) often must be 

 examined. 



{CAUTION: Beware of problematic hydric soils 

 that have colors other than those described above; 

 see problem area wetlands section, p. 55.) 



7) Iron and manganese concretions - During 

 the oxidation-reduction process, iron and manga- 

 nese in suspension are sometimes segregated as 

 oxides into concretions or soft masses. Concre- 

 tions are local concentrations of chemical com- 

 pounds (e.g., iron oxide) in the form of a grain or 

 nodule of varying size, shape, hardness, and color 

 (Buckman and Brady 1969). Manganese concre- 

 tions are usually black or dark brown, while iron 

 concretions are usually yellow, orange or reddish 

 brown. In hydric soils, these concretions are also 

 usually accompanied by soil colors described 

 above. 



8) Coarse-textured or sandy hydric soils - 

 Many of the indicators listed above cannot be ap- 

 plied to sandy soils. In particular, soil color should 

 not be used as an indicator in most sandy soils (see 

 problem area wetiands section, p. 55). However, 

 three soil features may be used as indicators of hy- 

 dric sandy soils: 



A) High organic matter content in the sur- 

 face horizon - Organic matter tends to accumulate 

 above or in the surface horizon of sandy soils that 

 are inundated or saturated to the surface for a sig- 

 nificant portion of the growing season. The mineral 

 surface layer generally appears darker than the min- 

 eral material immediately below it due to organic 

 matter interspersed among or adhering to sand par- 

 ticles. {Note: Because organic matter also accumu- 

 lates on upland soils, in some instances it may be 

 difficult to distinguish a surface organic layer asso- 

 ciated with a wetiand site from litter and duff asso- 

 ciated with an upland site unless the species com- 

 position of the organic materials is determined.) 



B) Dark vertical streaking of subsurface ho- 

 rizons by organic matter - Organic matter is moved 

 downward through sand as the water table fluctu- 

 ates. This often occurs more rapidly and to a great- 

 er 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 dark- 

 er area is rubbed between the fingers, the dark or- 

 ganic matter stains the fingers. 



C) Wet Spodosols - As organic matter is 

 moved downward through some sandy soils, it 

 may accumulate at the point representing the most 

 commonly occurring depth to the water table. This 

 organic matter may become slightly cemented with 

 aluminum. Spodic horizons often occur at depths 

 of 12 to 30 inches below the mineral surface. Wet 

 spodosols (formerly called "groundwater podzolic 

 soils") usually have thick dark surface horizons 

 that are high in organic matter with thick, dull gray 

 E-horizons above a very dark-colored (black) 

 spodic horizon. (CAUTION: Not all soils with 

 spodic horizons meet the hydric soil criterion; see 

 p. 58.) 



(Note: In recently deposited sandy material, 

 such as accreting sand bars, it may be impossible 

 to find any of the above indicators. Such cases are 

 considered natural, problem area wetlands and the 

 determination of hydric soil should be based on 

 knowledge of local hydrology. See p. 57-58). 



Wetland Hydrology 



3.29. The driving force creating wetlands is "wet- 

 land hydrology", that is, permanent or periodic in- 

 undation, or soil saturation for a significant period 

 (usually a week or more) during the growing sea- 

 son. All wetiands are, therefore, at least periodical- 

 ly wet. Many wetiands are found along rivers, 

 lakes, and estuaries where flooding is likely to oc- 

 cur, while other wetlands form in isolated depres- 

 sions surrounded by upland where surface water 

 collects. Still others develop on slopes of var>'ing 

 steepness, in surface water drainageways or where 

 ground water discharges to the land surface in 

 spring or seepage areas. 



3.30. Numerous factors influence the wetness of 

 an area, including precipitation, stratigraphy, to- 

 pography, soil permeability, and plant cover. The 



15 



