Avery and Weeks Islands
Salt Dome Geology and Geography
Salt Dome Origin and Morphology
The Five Island Region
Cultural Trace and Land Division
Coastal Land Loss
Cultural and Historical Development
Exploration and Exploitation
Oil and gas activities
Height above Sea Level
Avery and Weeks Islands, Louisiana
Salt Dome Geology and Geography
Louisianas near featureless marshes and adjacent water bodies span the entire coast. They vary in width from 25 kilometers (15.5 miles) to 80 kilometers (50 miles). There is, in fact, less than 4 meters (13 feet) difference in height between marsh habitats and adjacent natural levees, cheniers, and beaches. Relief is often less than 0.3 meter/ kilometer (0.6 foot/mile) over hundreds of square kilometers. A one-meter shift in elevation is enough to shift from soft wet soils of the wetland marshes to firm habitable land. The "Five Island" region of south Louisiana, named for the linear arrangement of five salt domes, is a fine example of how a shift in elevation makes a great difference in the type of habitats the area exhibits. Here, near surface salt domes, such as Avery, Belle Isle, Cote Blanche, Jefferson, and Weeks Islands, rise to more than 40 meters (130 feet) above the surrounding marshes. They are the regions most conspicuous features.
East of Marsh Island is the Deltaic Plain. Within its boundaries are more than 9,000 years of deltaic morphology, exemplified by a highly irregular shoreline characterized by natural levees, marshes, swamps, bays, lakes, and barrier islands. This region consists of a series of shifting, prograding sedimentary lobes deposited by the Mississippi River. These lobate masses are named after their main stream channel (Figure 1). As a result of this sequential shifting, the Deltaic Plain extends for almost 320 kilometers (200 miles) along the coast and more than 100 kilometers (60 miles) inland (Pearson and Davis, 1995). Topographic relief is generally less than 4 meters (13 feet).
The study area is a landscape dominated by broad, gently sloping natural levees, marshes, swamps, and exposed salt domes. Flanking the natural waterways on both sides are natural levees. The crest of these levees is near the stream, river or bayous bank. The backslope is generally so slight that it is not easily recognized. A levees height and width are directly proportional to the size of the water body that created them. During a flood, a streams velocity decreases away from the main channel, permitting the heavy and coarse sediments to be deposited on the bank near the river. Through recurring floods, the river or bayous banks are elevated higher and higher, producing an easily defined system of natural levees that served the regions agricultural, transportation, and settlement needs. In addition, frequent flooding diverted sediments into the surrounding lowlands, often through crevasses, elevating the surface at a rate that counteracted subsidence and sea level rise.
Salt Dome Origin and Morphology
The Pleistocene Upland/Terrace has an elevation that approaches seven meters (23 feet) above sea level. These features are used primarily for agriculture. The highest features are domal structures punched up by shallow, cylindrical salt intrusions (Figure 2). These salt pillars have transverse cross-sectional areas that vary from 25,000 square meters (six acres) to 30 square kilometers (7360 acres). Most pillars are deep beneath the surface of the earth, but some that have risen near the surface have pushed up conspicuously rounded hills, the so-called "salt domes". The salt originates from a layer buried five miles beneath the surface. At this depth, the salt is under great pressure, and because it is less dense than the overlying layers of mud and sand, it deforms plastically and rises along zones of weakness. The rounded hills formed by these rising cylindrical plugs are one of the Gulf Coastal Plains outstanding features, especially where the rise in marshland creates "islands" with elevations up to 40 meters (230 feet).
Salt domes are of major economic importance. Salt, sulfur, and natural gas and petroleum, the most valuable of Louisianas mineral resources, are associated with salt intrusions. One salt intrusion, Avery Island, has spawned a multi-million dollar pepper sauce industry. The exact dimensions of the salt pillars are unknown. However, the total quantity estimated in some domes, such as Avery Island, is thought to be in excess of two billion tons of salt.
The Five Island Region
The "Five Islands" Jefferson, Avery, Weeks, Cote Blanche and Belle Isle are all near surface salt intrusions that mark a linear alignment of islands across south Louisiana. They form distinct natural landmarks in the relatively flat, featureless marsh and prairie that typify the region. Like all visible intrusive features, these domes vary in height, area, and surface topography. The surface topography of some of the "islands" can be complex and little related to stream erosion. Instead, it would appear to be more the result of subsurface salt solution, collapse, and faulting along the crest of the rising salt plug.
From a geological perspective, marshes are short-lived features a product of currents, waves or rivers carrying sediments into shallow coastal waters. Through time, these deposits vertically accrete to a point where the surface is then vegetated by a few hardy pioneer speciesmostly grasses that can tolerate the stress of tidal flooding and salt-water inundation. Species of the genus Spartina are the dominant marsh plants and make up one-fourth of the marsh vegetation bordering the Gulf of Mexico (Chabreck 1972). As it colonizes the fringing mudflats, Spartina stabilizes the surface and spreads slowly outward changing the water into an extensive grassy flat. Marsh grasses are especially important, as they absorb wave energy and help retard natural or storm-induced erosion. In the marsh, tree growth is limited to the coteauxs and ridges, locally called cheniers (English chenier). The "marsh" refers to the marshland, rather than the vegetational cover of grasses, sedges, and rushes. Older residents still refer to the area as "prairie" and "marais"a grassland, either wet or dry. Conditions vary from surfaces that are firm and can be walked upon, to those that require the use of a boat. The marais has been sub-divided into four vegetative types: saline, brackish, intermediate, and fresh.
Salt marshes generally conform to the 20 ppt salinity isohaline. It is dominated by oyster grass (Spartina alterniflora) whose abundance is in direct proportion to the water table and salinity conditions. Brackish plants tolerate salinities between 10 to 20 ppt and are categorized as either saltmeadow or rush. Saltmeadows are dominated by wiregrass (Spartina patens)a plant that makes up 25% of the coastal vegetation and is generally underlain by peat. Its major competitor is oyster grass. The intermediate band is characterized by wiregrass. The fluctuating water table has created a heterogenic vegetative assemblage capable of surviving in salinities that vary from 2 to 10 ppt (Penfound and Hathaway 1958; Wright et al. 1960). Included are salt grass (Distichlis spicate), roseau cane (Phragmites communis), and bulltongue (Sagittaria falcata). Freshwater marsh occupies an area where salinities are less than 2 ppt. It is a region dominated by canouche (Panicum hemitomon). Some areas of the fresh marsh are also characterized by a type of "trembling marsh" locally called flotant (Russell 1942; Chabreck 1972) that develops as a floating mat of vegetation on water or a muddy bottom.
Within the forested uplands of the five exposed salt domes, cypress and tupelo, willow, and water oak dominate the vegetative community. Wax myrtle, marsh elder, groundsee tree and sable palmetto characterize scrub-shrub wetlands.
Cultural Trace and Land Division
Any natural or man-made process that causes wetland erosion, denies sediment to wetlands, or leads to salt-water encroachment into wetlands, will result in loss of wetlands. Conversely, anything that reverses these processes leads to retention and expansion of wetlands. Over the past 50 years more than 3,885 square kilometers (1,500 square miles) of marshland have disappeared from Louisianas Gulf Coast. Just over 12,950 square kilometers (5,000 square miles) of salt-water, brackish and freshwater wetlands now remain. These remaining wetlands support a delicate ecosystem that is a spawning ground and nursery for a multitude of young fish, crabs, oysters, and shrimp. In addition, wetlands also filter pollutants out of runoff, reduce flooding, provide habitat for many waterfowl and other wildlife and protect the coast from storm surges and rising sea level. An estimated 98% of the commercially important fish in the Gulf of Mexico begin their lives in these coastal wetlands. These important hatcheries are now sinking under their own weight, as the natural processes of compaction and subsidence progress. Humans also impacted this delicate ecosystem. With leveeing of the Mississippi River, river water and sediment that would replenish this region during flooding events is now funneled into the deep waters of the Gulf of Mexico. For more than 50 years the oil and gas industrys dredging contracts built a maze of navigation channels and oil field canals in order to access their oil fields. Boat traffic in these engineered canals caused erosion problems along the waterways banks. In addition, these channels provided avenues for salt water to intrude deep into areas once containing brackish or fresh water marshes. This resulted in increased rates of erosion as fresh- and brackish-water plants that hold the marsh soil together died as salt water crept into their area.
Coastal Land Loss
Between 1955 and 1975 it is estimated that in the contiguous United States more than 220,000 hectares (543,600 acres) of wetlands were lost annually, most of this is attributed to mans activities (Wetland: Their use ..., 1984). Currently, the rate of loss has decreased slightly, largely due to reduction of agricultural reclamation. This has benefited upland wetlands, but is insignificant in the coastal zone where the land loss problem is critical. Parts of Louisianas coastal shoreline are disappearing at more than 30 meters/year (100 feet/year).
Louisianas coastal lowlands are also facing a serious dilemma. The problem is related directly to humankinds interference with the Mississippi Rivers flow regime and the effects of erosion induced by natural processes and sea-level rise/global warming. Erosion has taken over; more than 65 square kilometers (25 square miles/year) of marshland disappear annually. At that rate, every five years the coast loses an area greater than New Orleans. Some believe that unless corrective measures are initiated soon, the damage to the fragile ecosystems may soon reach the point of irreversibility. Further, wind and waves are causing the states barrier islands to move landward at rates up to 20 meters/year (65 feet/year); they have lost nearly half of their surface area in the last 100 years (Penland and Boyd 1982; Baumann and DeLaune 1982; Boesch et al. 1983; Turner et al. 1987; Penland et al. 1990; McBride et al. 1991; Boesch et al. 1994). Consequently, a large portion of the coastal lowlands will erode away in the next 200 years.
Cultural and Historical Development
Native Americans have occupied the Mississippi Delta region since before the first delta complex, the Maringouin, became active (7,300 year before present). Researchers have used archaeological data, such as distinctive ceramic assemblages, from these Native American settlements to suggest a relative chronology of deltaic landforms of the Mississippi deltaic plain (Kniffen, 1936; Pearson and Davis, 1995). Further, the Native Americans were quite instrumental in showing the European colonists how to survive in Louisianas alluvial wetlands. The first Europeans to settle these low-lying floodplains of south Louisiana were a group of rural Roman Catholic French Canadian refugees, the Cajuns, or Acadians. They were driven from French Canada by the English in 1755 during what is known as "Le Grand Derangement." Henry Wordsworth Longfellow, in his poem Evangeline, tells the sad story of Gabriel and Evangeline and their separation from and search for, each other in exile, and their sad reunion (see separate article).
As small landowners, the Acadians enjoyed the seclusion and solitude provided by Louisianas physical geography. It was an ideal setting to start a new life. They became farmers, trappers, and fishermen, providing south Louisiana with its own cultural identity. The regions rich alluvial soils, abundant hide- and fur-bearing animals, and easily harvested aquatic life were infinitely attractive, just as they had been to the Native American inhabitants. The Acadians were followed by Isleños (Canary Islanders), Austrian, Slavic, Chinese, German, Philippine, Irish, Latin American, African American, and Italian settlers. These populations, along with the Cajun and Native American populations have created a cultural montage of ethnic communities across coastal Louisiana. The Deltaic Plains initial settlements were essentially isolated from the uplands by the regions "inhospitable" swamp and marsh "wasteland." Each culture group brought with them widely differing customs, which became muted over time as each group struggled to adapt to the deltaic environment. There are about a million French-speaking descendants of the Acadians living in South Louisiana. It is not uncommon to find "Cajuns" with non-French surnames like Schexnieder, Robert, Allemand, Richard, Huval and Henry - a testimony to the forces that formed the distinctive "Cajun" culture. Another distinct culture of the Mississippi deltaic plain is that of the "Creoles" defined as native born descendants of French or Spanish ancestry or of both. As an adjective the term applies to their manners, usages, and inventions, such as creole customs, creole tomatoes, and creole cooking. For example, black Creoles trace their roots back to immigrants of Caribbean and/or African descents. As a result, these two French-speaking groups boast distinctive music - the Cajun French and the African-influenced Zydeco.
In Louisiana, settlers migrated to the states isolated wetland landscapes, and acquired cultural practices that are identified with an annual use cycle tied to the regions natural resource base. Therefore, this geographic complex is a product of two distinct ingredients: one natural and the other cultural, or human. Topographic relief soils, landforms, vegetation, climate, and other
natural qualities and agents are often self-evident. Cultural elements demography, ethnicity, acculturation, cultural adaptation and heritage are not observed as easily. In reality, these cultural and/or social identifiers are often the foundation for the lowlands importance as a productive environment. Moreover, exploitation patterns cannot be explained by land characteristics alone.
Within the study area there are numerous relic archeological sites and historical settlements that have been affected by the regions changing physical conditions. Archeological sites are perhaps the most noteworthy, since pre-historic Native Americans established their villages on the areas natural levees, exposed salt domes, beach ridges and other high-ground features. There are, in fact, several thousand relic midden sitesdefined as an accumulation of refuse around an Indian dwelling place within the coastal lowland. Since early cultures had to adapt to a changing environment, settlements were rarely continuously occupied. In Louisiana, pre-historic cultures followed the changing patterns of the Mississippi River.
Historic settlements followed the same pattern, but rather than move as the environment changed, the regions natural waterways were managed to prevent change and guarantee the viability of the settlements. European settlers took full advantage of the regions resource base. As a result, many cultural components survive dispersed and agglomerated settlements, linear hamlets, T-towns, and grid cities, plantations, folk houses, boats, fences and barns, white-washed, above-ground graveyards, and other elements of the regions material culture. To some these elements are not important, to others they are links to their heritage.
The earliest evidence of human activity in south Louisiana is associated with a site on Avery Island. Stone tools, which have been radiocarbon dated, suggest this site is more than 11,000 years old (Weinstein and Gagliano 1985). Detailed written records are nonexistent, so each group is "finger printed" by their material culture, such as their stone tools or ornamental pottery. The artifacts found in or on the ground provide the data to unravel the regional settlement succession. The cultural remains, therefore, provide many clues in assessing the natural setting during aboriginal time.
As early as the 1730s, French Creoles were beginning to exploit the deltaic wetlands. Initially, the regions natural commodities attracted them: in particular, its timber and shell resources. The timber came from the areas vast bald cypress (Taxodium distichum) and tupelo gum (Nyssa aquatica) forests - the two primary tree species in Louisiana swamps. The shell used by the French Creoles was derived from the wetlands numerous Native American shell middens. Shell middens are refuse mounds that mark many of the archeological Native American sites throughout Louisiana. The shells found in these middens are from an oyster known as Rangia. Rangia was a primary food source for the Native Americans in this area and is thus a major component of many of their middens. The Creoles recovered the shell material, which was then burned and converted to lime for use primarily in construction endeavors in the colony (Pearson et al. 1989A; Pearson et al. 1989B).
Originally, the economy was subsistence driven. With time, this economy became more money and entrepreneurial oriented. Agricultural products (sugarcane, cattle, rice and other crops), sulfur, oil, natural gas, fresh- and saltwater fisheries, and the regions trapping resources developed in response to national and international market demands. The regional economic mainstay, therefore, revolved around a market that is national and international in scope. Consequently, there evolved a large concentration of people confined to wetland-dominated habitats. As the regions population expanded, rural settlement clusters began to discover their own economic niche. Each community acquired its own distinctive employment identity, from agricultural nodal points, to oil and gas support centers, and ports and seafood processing centers. The economy benefited from the abundant renewable and nonrenewable resource base. The survival of many of these communities attests to the tenuous nature of living within the coastal lowlands. They have survived hurricanes, employment cycles, and emigration; they have adapted to their conditions.
To succeed and exist in this dynamic, and sometimes inhospitable, environment, the population developed and utilized innovative engineering techniques, unconventional wisdom, and unique cultural occupancy patterns always with an eye towards maximizing the regions renewable resource base (Brasseaux 1985; Brasseaux 1987). As a result, local government has invested in barrier island research and restoration, water-control structures, levee fortification, locks and gates on key natural and engineered waterways, extensive pump systems and forced drainage projects, canals and ditches to improve flood control, and other pubic works-type projects.
Ultimately, the population expanded by constructing their homes, hamlets, villages, towns and industrialized cities on protected and well-drained natural levee land. As a result, a settlement pattern was initiated that evolved from the regions distinctive morphology and resource base.
These wetland inhabitants took advantage of all available high ground, regardless of how small or insignificant, much as their Native American predecessors.
Exploration and Exploitation
Landowners along the regions rivers and bayous typically had long, narrow tracts of land that fronted the river and extended back away from it locally called arpents which is a French length measurement equal to about 58.5 meters (192 feet). This land-division system allowed each property owner to have river frontage an important commodity during this time, as produce and materials were primarily moved to market by way of the river. In addition, the depth of the property guaranteed landowners had access to the natural levees rich alluvial soils as well as the timber and other resources of the regions backswamps. Early settlers had land holdings a few arpents wide and 40 arpents long.
South Louisianas favorable climate and fertile alluvial soils, allow almost every crop indigenous to the western hemisphere to be raised in the coastal zone. Agricultural activities have therefore occupied an important position in the areas social and economic environment. The wealth gained from hydrocarbons, commercial fishing and trapping, industrial development, and tourism do not overshadow the value of agricultural products. The dominant crops are sugarcane and rice.
Sugar cane was introduced into Louisiana in 1751 when a small quantity was planted and cultivated near New Orleans. Although planters tried unsuccessfully to manufacture sugar, the original cane crops were used primarily for chewing. Development of a process for granulating sugar in 1794 allowed sugarcane to become a commercial crop in Louisiana. With establishment of the industry, indigo production was abandoned in favor of sugarcane (Sitterson 1953, Taggart and Simon 1957, Hansen 1971). Rice, introduced in the early 1700s continued to be commercially exported to Europe until the late 1800s.
Although sugar cane and rice continue to be important products produced in the study area, increase in production costs is causing many sugar mills to close. Farmers have, therefore, had to alter their traditional transportation patterns, and the cost of transporting cane from the field to the mill becomes excessive. Farmers must abandon the industry, produce another agricultural crop, or sell out. Growers who continue to produce cane often haul their produce 50 kilometers (30 miles) or more to a mill.
Few people recognize Louisiana is North Americas largest fur-producer. In the early 20th century Louisianas annual harvest was greater than Alaska and Canada combined. Pelts harvested in Louisiana include many species, such as the muskrat, nutria, raccoon, mink, otter, opossum, fox and bobcat. However, the animals responsible for the spectacular growth in the early fur trade were the muskrat (Ondatra zibethicus rivalicius) and nutria (Myocastor coypus). Colonial fur buyers regarded the muskrat as worthless. It remained unwanted until 1914 when pelts began to appear on the fur market (Chatterton 1944). In a relatively short period of time the muskrat was destined to become Louisianas preeminent fur-bearer a title it ultimately relinquished to the nutria.
Unlike the indigenous muskrat, nutria, or the South American coypu, are alien animals. After escaping captivity in 1938 from enclosures on Avery Island, this Argentinian rodent has expanded its range to include most of Louisianas swamps and marshes. Quickly, the prolific rodent began to replace the muskrat. By the 1950s trappers were annually marketing nearly 80,000 nutria pelts. Six years later more than 500,000 were processed a remarkable increase in less than 20 years. Recently the fur trade has suffered a large downturn in the market, and in the 1995-96 season, 188,000 nutria pelts were brought to market. These nutria pelts are valued at about $500,000 and represent about 1/3 of Louisianas fur trade (Louisiana Almanac, 1997). Today, nutria is still considered a nuisance and is blamed, in part, for wetland loss because they tend to cause "eatouts where the vegetation is virtually wiped out. Since the fur trade business is currently depressed, some groups are looking for ways to control and reduce nutria populations. One inventive solution proposed to address the nutria problem is to improve the nutrias public image and market its meat to the grocery stores and the public.
Called by the Spanish el largarto (the lizard) the alligator (Alligator mississipiensis) has been harvested commercially since the mid-1800. As late as 1890 some 280,000 alligator skins were being processed annually in the United States. Between 1880 and 1904 hide hunters significantly reduced the species. For a period of time in Louisiana alligators were a protected species. However, Alligators have now recovered to a point in Louisiana where Louisiana has a controlled alligator hunt in September. During this season about 25,000 alligators are harvested. These skins bring more than $5 million dollars at the market. Furthermore, alligator meat is now a novelty item on many restaurant menus. Since the season is so short, and demand for alligator products high, more than 100 commercial alligator farms are operating in Louisiana.
In Louisiana, intensive bald cypress exploitation began after the Timber Act of 1879 repealed the Homestead Act of 1866. As a direct result of the Acts repeal, vast cypress/tupelo tracts were sold for less than $1.25 a hectare ($.60 an acre). Consequently, by 1890 a sizeable percentage of Louisianas swamps were managed by the forest-products industry. Ingress and timber removal were of paramount concern. Access problems were resolved by excavating canals to the logging sites. Removal of the cut timber was accomplished by using steam engines aboard pullboats that dragged logs into a dredged channel. To utilize a pullboat effectively, lumber companies dredged primary and secondary watercourses leading to logging sites which incorporated a series of intersecting channels with fan-shaped cable runs radiating out from points along the access routes. These radial designs were etched into the landscape by the cables required to "snake" the logs into the principal channel. These canals and pullboat scars remain, although many of these logging operations occurred more than fifty years ago. This distinctive radial design can be detected on aerial photography today and are an accurate record of intensive lumbering operations of the past. In a larger sense, these scars are an indicator of the once robust cypress trade and the near complete depletion of virgin cypress/tupelo swamps.
Oil and gas activities
Mariners sailing off the coast of Louisiana and Texas in the 1600s recorded one of the earliest known natural oil seeps. They shrugged it off as unimportant, as there was no market for the substance they witnessed. The seepage, however, provided a tiny clue to the vast storehouse of hydrocarbons trapped in the earths crust, extending from the uplands through Louisianas swamps and marshes, and into the subaqueous habitats of the Gulf of Mexico. As the oil and gas industry expanded, each move into a new geographic area often required a considerable change in how the oil and gas were recovered. This led to advances in the science and technology supporting the exploration and development of Louisianas petrochemical resources.
In August 1901, through the Jennings Oil Company, the first producing oil well was completed in Louisiana less than a year after the discovery at Spindletop in southeast Texas. Even though the Jennings/Evangeline field was a success, promising fields were just too much trouble to exploit (Franks and Lambert 1982). The industry turned its attention to Caddo Lake in north Louisiana. However, by the 1920s, oil and gas wildcatters were starting to look at south Louisianas subsurface geology. Today, oil and/or gas are being produced in all of Louisianas 64 parishes.
Wetland exploration required boats, barges, and port facilities. These elements were not available or did not exist. Exploration and development was not practical until the 1930s, when the required support facilities were available (Larson et al. 1980; Davis and Place 1983). Access was critical, so suction or bucket dredges were used to cut channels through the swamps and marshes. Pipeline corridors were also cut through the marsh peat. Consequently, the associated canal and pipeline rights-of-way represent a labyrinth of tributary lines that coalesce into an integrated, complex network of transport arteries (Davis 1992). Louisianas alluvial wetlands are, therefore, laced with canals and subaqueous pipelines (Tabberer et al. 1985; Wicker et al. 1989A and 1989B). These are important commercial arteries that allow the petrochemical industry to gain access to the more than 32,000 oil and/or gas wells in the 789 fields in the 25 coastal parishes. They are harmful, however, in that they provide conduits for the encroachment of salt water into valuable marshland.
The industry changed in 1947 when a consortium led by Kerr-McGee (at that time an Oklahoma independent) successfully completed a well out-of-sight of land (Barnes and McCaslin 1948). Within seven years after the initial offshore discovery, oil companies extended the offshore frontier to 50 miles. By 1955 more than 40 offshore rigs were in operation (Larson et al. 1980; Davis and Place 1983). Currently, new technology and the lure of large finds in deepwater off Louisianas coast has resulted in development of exploration and production facilities in more than 853 meters (2800 feet) of water. By 1999 these facilities will be operating in water at least double this depth making offshore Louisiana one of the most important oil and gas provinces in the world
TOTAL PERSONS 1900-1980
1900 1910 1920 1930 1940 1950 1960 1970 1980 Louisiana 1,381,625 1,656,388 1,798,509 2,101,593 2,363,880 2,683,516 3,257,022 3,641,306 4,205,900 Iberia Parish 29,015 31,262 26,855 28,192 37,189 40,059 51,657 57,397 63,752
TOTAL PERSONS Percent Change 1910-1990
1900-1910 1910-1920 1920-1930 1930-1940 1940-1950 1950-1960 1960-1970 1970-1980 1980-1990 Louisiana 19.88 -8.58 6.85 12.48 13.52 21.37 14.32 15.50 .33 Iberia Parish 7.74 -0.14 4.98 0.32 7.72 0.29 0.11 0.11 7.09
CENSUS and PROJECTIONS 1994-2020
TOTAL PERSONS Percent Changes Projected Population 1990-2020
Age Structure 1990
|Years of Age||Louisiana||Iberia Parish|
|0 – 4||313,349||5,891|
|5 – 17||878,063||16,325|
|18 – 24||474,896||7,473|
|25 – 44||1,272,081||20,458|
|45 – 64||926,826||15,109|
Selected Age Structure
Projections to 2020
Enumeration and Percent of Population
|Under 20 years||23,760||34||24,420||35||24,610||34||24,530||12||24,840||32||25,130||31||25,730||31|
|65 years and over||7,240||10||7,800||11||8,430||11||9,020||32||9,990||13||11,600||14||13,560||16|
of People in Industry
Employed persons 16 and over
|Employed persons 16 and over||25,256|
|Agriculture, foresty, and fisheries||41,805||879|
|Transportation, communications, and other public utilities||49,183||1,389|
|Finance, insurance, and real estate||94,423||1,021|
Height Above Sea Level
|Location||Height in feet|
|Avery Island||152 ft|
|Weeks Island||177 ft|
Commuting to work
|Workers 16 years and over||24,959|
|Percent drove alone||74.2|
|Percent in carpools||18.5|
|Percent using public transportation||0.6|
|Percent using other means||1.9|
|Percent walked or worked at home||4.8|
|Mean travel time to work (minutes)||20.5|
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Information is selected from:
National Science Program
Through Clemson University, Clemson, South Carolina
Wetland Education Through Maps and Aerial Photography
U.S. Geological Survey
National Wetland Research Center
Chadron State College, Chadron Nebraska
NASA Regional Applications Center, University of Louisiana in Lafayette, Louisiana