TABLE 1 (continued)
Principal Soil Deposits
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*
*
Pertinent Engineering *
*
Major
* Division
*
*
*
Principal Soil Deposits
Characteristics
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*
*
*
* TRANSPORTED
* SOILS -
*
*
*
*
*
*
*
* Alluvial
*
*
*
* ))))))))
*
*
*
*
*
*
*
* Material
* Floodplain deposits. Deposits laid *
*
* transported
* down by a stream within that portion*
*
* and deposited * of its valley subject to inundation *
*
* by running
* by floodwaters.
*
*
* water.
*
*
*
*
*
* Generally favorable
*
Point bar. Alternating
*
*
deposits of arcuate ridges and * foundation conditions; *
*
*
* however, detailed
*
swales (lows) formed on the
*
*
* investigations are
*
inside or convex bank of
*
mitigating river bends. Ridge * necessary to locate
*
*
*
*
* discontinuities. Flow *
deposits consist primarily of
*
*
* slides may be a problem *
silt and sand, swales are
*
*
* along riverbanks. Soils*
clay-filled.
*
*
* are quite pervious.
*
*
*
*
*
*
*
* Fine-grained soils are *
Channel fill. Deposits laid
*
*
down in abandoned meander loops * usually compressible.
*
*
*
* Portions may be very
*
isolated when rivers shorten
*
*
* heterogeneous. Silty
*
their courses. Composed
*
*
* soils generally present *
primarily of clay; however,
*
*
silty and sandy soils are found * favorable foundation
*
*
*
at the upstream and downstream * conditions.
*
*
*
*
*
ends.
*
*
*
*
*
*
* Relatively uniform in a *
Backswamp. The prolonged
*
*
* horizontal direction.
*
accumulation of floodwater
*
*
* Clays are usually
*
sediments in flood basins
*
*
* subjected to seasonal
*
bordering a river. Materials
*
*
are generally clays but tend to * volume changes.
*
*
*
*
*
become more silty near
*
*
*
*
riverbank.
*
*
*
*
*
* Alluvial Terrace deposits.
* Usually drained,
*
*
* Relatively narrow, flat-surfaced,
* oxidized. Generally
*
*
* river-flanking remnants of
* favorable foundation
*
*
* floodplain deposits formed by
* conditions.
*
*
* entrenchment of rivers and
*
*
*
* associated processes.
*
*
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7.1-3