Figure 17.—Indicator A12, Thick Dark Surface.
This photo accompanies Figure 17.—Indicator A12, Thick Dark Surface. [Field Indicators of Hydric Soils in the United States].
A typical landscape of the Tonka soil series (Argiaquic Argialbolls). The tonka series consists of very deep, poorly drained, slowly permeable soils that formed in local alluvium over till or glaciolacustrine deposits. These soils are in closed basins and depressions on till and glacial lake plains and have slopes of 0 to 1 percent.
Runoff is ponded. A seasonal high water table is at a depth of 0.5 foot above the surface to 1 foot below the surface at some time during the period April through June. It is used for small grains, hay and pasture. Native vegetation is tall grasses, sedges and rushes.
The series is extensive on the glaciated plains of North Dakota, northeastern South Dakota, and western Minnesota.
Figure 17.—Indicator A12, Thick Dark Surface.
This photo accompanies Figure 17.—Indicator A12, Thick Dark Surface. [Field Indicators of Hydric Soils in the United States].
A typical landscape of the Tonka soil series (Argiaquic Argialbolls). The tonka series consists of very deep, poorly drained, slowly permeable soils that formed in local alluvium over till or glaciolacustrine deposits. These soils are in closed basins and depressions on till and glacial lake plains and have slopes of 0 to 1 percent.
Runoff is ponded. A seasonal high water table is at a depth of 0.5 foot above the surface to 1 foot below the surface at some time during the period April through June. It is used for small grains, hay and pasture. Native vegetation is tall grasses, sedges and rushes.
The series is extensive on the glaciated plains of North Dakota, northeastern South Dakota, and western Minnesota.