Surface Features & Physiography (Stewart 2003)

Land above sea level is subject to the unceasing erosional effects of wind and running water aided by gravity. Running water is the chief agent of erosion and the effects of erosion differ according to the type of sediments being eroded. Clays tend to erode as more or less flat surfaces, whereas sands, silts and gravels form ridges and valleys. That much of Mississippi is characterized by ridges and valleys is a reflection of the abundance of sands, silts and gravels in the state. Thus the topography (shape of the land surface) is a direct result of the interaction of the surface geology and the climate.

Soils are determined by topography, surface geology, climate, vegetation and other life, and time. In turn natural vegetation is determined by climate, topography, soils, other biological influences, and time. In Mississippi, the various combinations of these factors has made possible the recognition of at least 10 regions known as physiographic regions or physiographic provinces. Each physiographic region has a more or less unique combination of surface geology, soils, topography, vegetation, and geologic history. Brief summarizations of the characteristics of these 10 physiographic regions follow.

Tombigbee Hills (also known as the Tennessee River Hills, an extension of the Fall Line Hills which are formed by the innermost coastal plain deposits extending across Alabama into Georgia)

Geology: sands, clays, and gravels of the Tuscaloosa and Eutaw formations (Cretaceous).
Topography: ravines and ridges, numerous streams; highest part of the state with an average of about 650 feet above sea level; high point is Woodall Mountain at 806 feet is in Tishomingo County.
Soils: highly weathered, acid
Soil Orders: very old ultisols, few alfisols, entisols in stream drainages
Vegetation: Hardwoods and pine (shortleaf and loblolly pine). With exception of a small outlying population in Calhoun County (North Central Hills), the only province with chestnut oak
Reference towns: area lies east and northeast of Tupelo; Corinth, Baldwyn, and Amory on western edge.

Blackland Prairies or Blackbelt

Geology: chalks or marls of the Selma Group (especially the Demopolis Formation); Cretaceous.
Topography: flat to gently undulating
Soils: clays prominent, often calcareous (containing calcium carbonate); some well-drained acidic overburden over chalk
Soil Orders: mostly dark-colored alkaline vertisols, few entisols and inceptisols, rare mollisols
Vegetation: original vegetation not well known but probably scattered trees with prairie grasses and wild flowers. Some tree species are bur oak, durand oak, chinkapin oak, nutmeg hickory, and carolina buckthorn.
Reference towns: Tupelo, Aberdeen, West Point, Starkville (western edge), Columbus (eastern edge).

Pontotoc Ridge

Geology: sands, clays, marls. Ripley Formation forms an escarpment or cuesta on the east where it joins the Blackbelt. Prairie Bluff Chalk and Clayton Formation form the central and western portions of the ridge which grades smoothly to the Interior Flatwoods on the west. Cretaceous.
Topography: ridges and valleys
Soils: highly weathered, acid and calcareous, mostly acid
Soil Orders: mostly ultisols, some alfisols, rare Mollisols
Vegetation: hardwoods and pine on acid sites; prairie species on calcareous sites.
Reference towns: Ripley, New Albany, Pontotoc, Houston, Starkville (southern tip)

Interior Flatwoods

Geology: Porters Creek Clay (marine). Paleocene.
Topography: nearly level to level
Soils: acid clays & clay loams
Soil Orders: mostly alfisols, with entisols in river drainages
Vegetation: hardwoods, mostly adapted to wet winter-spring
conditions
Reference towns: Vardaman (western edge), Houston (eastern edge); extends northward between Oxford (North Central Hills) and Pontotoc (Pontotoc Ridge); continues southeastward as a narrow belt lying just west of Starkville.

North Central Hills

Geology: sands and clays of the Wilcox Group (Paleocene) and Claiborne Group (Eocene). Influence of loess increases westward toward the Loess Bluffs region.
Topography: ridges and valleys
Soils: mostly acidic
Soil Orders: mostly alfisols toward west, ultisols to east, entisols in drainages
Vegetation: hardwoods and pine (loblolly and shortleaf)
Reference towns: Holly Springs, Oxford, Grenada (transitional to Loess Bluffs), Winona, Kosciusko, Louisville, Philadelphia, Meridian .

Loess Bluffs or Brown Loam Hills

Geology: sand, clays and gravels of Tertiary age (formations and epochs vary) overlain by up to 90-100 feet of loess (wind-blown late Pleistocene silts).
Topography: steeped-sided ravines and narrow ridges
Soils: acid to non-acid; the brown loam region of the state
Soil Orders: mostly alfisols in bluffs, entisols in bottoms and drainages
Vegetation: hardwoods including chinkapin oak and yellowwood. Affinities with western Tennesse to the north. Oak-beech-magnolia associations common from Vicksburg and southward.
Reference towns: Memphis (TN), Charleston, Grenada (transitional to Northcentral Hills), Yazoo City, Vicksburg, Port Gibson, Natchez.

Delta or Yazoo-Mississippi Basin (Alluvial Floodplain of the Yazoo & Mississippi Rivers)

Geology: Pleistocene to recent sand, silts and clays (and mixtures) deposited by the Mississippi River and its tributaries cover the older coastal plain sediments which are the same as those to the east.
Topography: level to very gently undulating areas near the Mississippi River and around abandoned and extinct river channels.
A complex arrangment of swamps, sloughs, meander scars, and overbank deposits including natural levees and backswamp deposits.
C.Soils: mildly acidic to mildly alkaline; young soils developing from
alluvium
D.Soil Orders: mostly inceptisols, entisols in stream drainages, alfisols, vertisols, rare mollisols
E.Vegetation: bottomland hardwood forests. Trees include nuttall oak, cedar elm, delta post oak, kentucky coffeetree (rare), swamp cottonwood, pumpkin ash, baldcypress, tupelogum
F. Reference towns: Tunica (north), Clarksdale, Cleveland (west-central), Greenville (west), Greenwood (east), Rolling Fork (south), Yazoo City (south, in part).

Central Blacklands or Jackson Prairies

Geology: clays, marls, and limestones of the Jackson and Vicksburg groups.
Topography: some rolling, other areas of ridges and valleys
Soils: acid to non-acid
Soil Orders: mostly ultisols, some alfisols
Vegetation: mixed including prairies and various mixtures of pine and hardwoods; transitional from upper coastal plain to lower coastal plain
Reference towns: Jackson, Waynesboro

Pine Hills (Longleaf Pine Belt)

Geology: clays, sands, and gravels of late Tertiary age; major formations are the Catahoula Sandstone, Hattiesburg Fm., Pascagoula Fm., and Citronelle Fm.
Topography: from rolling to areas of steep-sided ridges and valleys
Soils: acid
Soil Orders: Mostly ultisols, few alfisols, entisols along stream drainages
Vegetation: west of the Pearl River the forests resemble those of the upper coastal plain with mixed hardwoods along with loblolly and shortleaf pine and influence of loess from the west. East of the Pearl River is the main region of longleaf Pine with typical lower coastal plain forests including slash pine, spruce pine, turkey oak, bluejack oak, laurel oak, titi, red bay, southern magnolia, bigleaf magnolia, gallberries
Reference towns: west of Pearl River—Crystal Springs, Brookhaven, McComb, Woodville (strong loess influence); east of the Pearl River—Mendenhall, Laurel, Hattiesburg, Columbia, Poplarville, Wiggins, Lucedale, Picayune

Coastal Flatwoods (Coastal Pine Meadows)

Geology: young deposits of clay, silt, sand, and gravel; Pleistocene and Recent.
Topography: flat, rising gently inland from the shore; a belt about 10-15 miles wide and parallel to the coast.
Soils: acid, including areas of boggy soils with high organic content
Soil Orders: mostly ultisols, few entisols, inceptisols, few histosols; rare spodosols
Vegetation: similar to the southern part of the Pine Hills; low sandy bluffs 5-10 feet above sea level along the shore support live oaks, southern magnolia, and saw-palmetto; along the shore are the saline marshes with black needlerush and cordgrasses; fire-dependent savannas with slash pine include numerous grasses, sedges, and carnivorous plants (pitcher plants and sundews).
Reference towns: Pascagoula, Ocean Springs, Biloxi, Gulfport, Bay St. Louis, New Orleans (LA), Mobile (AL)