ecological characterization atlas of coastal alabama - Data Center

atlas maps . Although the information appears to be fairly accurate and
detailed at the 1 :100,000 scale, it is still generalized, and the 1 :20,000
scale maps within the soil survey should be consulted for detailed information
.
The soil surveys of Mobile and Baldwin Counties were classified 18 years
apart (field work done in 1978 and 1960, respectively) by different soil
scientists using different classification schemes . While this is not an
unusual situation, the result is that the soil association methodologies used
in the two counties are almost mutually exclusive . The soil names used in
the 1960 Baldwin County survey have been translated into more modern nomenclature
for inclusion in this atlas (G . L . Hickman, Soil Conservation Service,
Grove Hill, 10 May 1982 ; pers . comm .) .
Baldwin is the largest county in Alabama, with a surface area of 4,178
km2 (1,613 mi2, 1,032,320 acres, 418,090 ha), while Mobile County covers
3,212 km2 (1,240 mi2, 793,472 acres, 321,356 ha) . Elevations range from sea
l evel to abo ut 104 m (340 ft) i n Mobi l e County and abo ut 91 m ( 300 ft) i n
Bal dwi n County . Both counti es 1 i e wi thi n the Lower Coastal P1 ai n of the Gul f
Coastal Plain physiographic province . Offshore, the coastal waters belong to
the Mississippi-Alabama Shelf Section of the Continental Shelf physiographic
province .
The Lower Coastal P1 ai n prov i nce i s subdi vi ded wi thi n the study area i nto
the Southern Pine Hills and the Coastal Lowlands . The lowlands include both
the alluvial and deltaic plains . The Coastal Lowland zone is a flat to
gently undulating plain along the Alabama coast which is continuous with the
alluvial and deltaic plains of the Mobile River delta . The lowlands range in
width from 16 km (10 mi) in the Mobile Delta to only 60 m (200 ft) along the
eastern edge of Mobile Bay, and are generally 3 to 8 km (2 to 5 mi) in width
along the Gulf of Mexico . The transition from Coastal Lowlands to Southern
Pine Hills may be quite gradual, or fairly abrupt, in the form of bluffs
(Alabama Coastal Area Board 1978) . Bordering the Mobile Delta, the alluvial
and deltaic plains and adjacent terraces are mainly silt and clay sediments
relocated from upstream in Recent or Pleistocene times . Elevation here
ranges from nearly sea level to only about 7 m (20 ft), making the area
vulnerable to frequent flooding and saltwater intrusion, particularly during
extreme tides or storms . Predominant soil associations of the alluvialdeltaic
plain include Axis-Lafitte (6), Dorovan-Levy-Iuka-Urbo (1), Dorovan-
Johnston-Levy (12), Annemaine-Wahee-Leaf (2), and Izagora-Bethera-Suffolk
(13) .
The Axis-Lafitte association (6) is level, very poorly drained marshland .
The Axis soils are loamy mineral soils of tidal flats . They are gray to
brown mucky sandy cl ay 1 oam overl yi ng gray sandy 1 oam wi th mottl es or streaks
of yellow or brown . The land is covered with dense stands of marsh cane,
marsh grass, and rushes . Lafitte soils comprise mostly black to brown mucky
organic material and are found at the mouths of streams and rivers . These
areas are mostly wetland wildlife habitat and undeveloped .
The Dorovan-Levy-Iuka-Urbo association (1) of Baldwin County and the
Dorovan-Johnston-Levy association (12) of Mobile County are the soils of the
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