Encyclopedic Entry

Swamps are usually humid places.

Photograph by Joseph Guillory, My Shot

Coal From Swamps
Ancient swamps are a source of the fossil fuel coal. Coal is formed from plants that died millions of years ago. The plant matter settled in layers at the bottom of swamps, where lack of oxygen kept it from decaying completely. Over time, pressure from accumulating layers caused the vegetation to harden, or fossilize, into coal. For centuries, coal has been burned and used as fuel. Deposits of this fossil fuel can be found on every continent.

Okefenokee Swamp
Okefenokee is a Native American word that means "trembling earth." At the Okefenokee Swamp in the U.S. states of Georgia and Florida, the land is so soggy that the trees do not have a stable hold in the ground and shake, or tremble, when people trod heavily nearby.

Pogo
One of the most important American satires of the 20th century took place in the Georgia section of the Okefenokee Swamp. Pogo, created by writer and artist Walt Kelly, was a comic strip that ran from 1949-1975. During that time, the comic satirized American politicians like Sen. Joseph McCarthy (as a character called "Simple J. Malarky") and President Lyndon Johnson (instead of the Lone Ranger, he was "The Loan Arranger").

Pogo's characters were animals native to the Okefenokee Swamp: alligators, owls, skunks, and the title character, Pogo, an opossum. During the first Earth Day, in 1971, Pogo looked out on his garbage-infested swamp home and sighed, "We have met the enemy, and he is us."

A swamp is an area of land permanently saturated, or filled, with water. Many swamps are even covered by water. There are two main types of swamps: freshwater swamps and saltwater swamps.

Swamps are dominated by trees. They are often named for the type of trees that grow in them, such as cypress swamps or hardwood swamps. Freshwater swamps are commonly found inland, while saltwater swamps are usually found along coastal areas. Swamps are transition areas. They are neither totally land nor totally water.

Swamps exist in many kinds of climates and on every continent except Antarctica. They vary in size from isolated prairie potholes to huge coastal salt marshes. Some swamps are flooded woodlands. Some are former lakes or ponds overtaken by trees and shrubs.

Freshwater Swamps

Freshwater swamps form around lakes and streams. Rain and seasonal flooding cause water levels to fluctuate. In the wet soil, water-tolerant vegetation grows and helps maintain a moist, swampy condition.

In many freshwater swamps in the southeastern United States, cypress and tupelo trees grow. Spanish moss may hang from the branches, and tiny plants called duckweed may cover the waters surface. Shrubs and bushes may grow beneath the trees. Sometimes poking as much as 4 meters (13 feet) above the water are angular knobs called cypress knees. They are outgrowths of the trees' root systems.

Alligators, frogs, and many other animals live in these swamps. These animals are adapted to fluctuating water levels. The shadowy tree root system and cypress knobs provide a rich, sheltered habitat for nesting birds, as well as fish, amphibians and reptiles.

The freshwater swamps between the Tigris and Euphrates Rivers in the Middle East are so rich in biodiversity that the area is called the "Fertile Crescent." The abundant wildlife, agricultural opportunities, and ability for communication and trade fostered human technological development. The Fertile Crescent is recognized as the birthplace of civilization and the site of the first cities. The earliest recorded written language and the first recorded use of the wheel occurred around these swamps.

The Everglades, in Florida, is one of the largest swamp complexes in the United States. Called the "River of Grass," this freshwater swamp is actually a wide, slow-moving river flowing from the Kissimmee River near Orlando to the Straits of Florida. The Everglades is 97 kilometers (60 miles) wide and 160 kilometers (100 miles) long. A rich collection of wildlife, from alligators to panthers, calls this freshwater swamp home.

Saltwater Swamps

Saltwater swamps form on tropical coastlines. Formation of these swamps begins with bare flats of mud and sand that are thinly covered by seawater during high tides. Plants that are able to tolerate tidal flooding, such as mangrove trees, begin to grow and soon form thickets of roots and branches. Mangrove trees often grow on tall, thin roots. The roots anchor sand and other sediments. The growth and decay of the roots increase the accumulation of soil.

Among these mangroves live animals that feed on fallen leaves and other material. Crabs, conchs, and other shellfish are abundant in mangrove swamps. The swamps are also home to a huge variety of birds, whose droppings help fertilize the swamp.

Because the young of many marine animals find food and shelter in saltwater swamps, these wetlands are sometimes called the nurseries of the ocean. Many ocean species enter coastal wetlands to spawn. Fish swim into salt marshes to lay their eggs. When the eggs hatch, the young find plenty of food and some protection in swamp grasses or among tree roots. Other species spawn in the ocean, and the young swim into the wetlands and live there until they mature.

People and swamps

Swamps are among the most valuable ecosystems on Earth. They act like giant sponges or reservoirs. When heavy rains cause flooding, swamps and other wetlands absorb excess water, moderating the effects of flooding. Swamps also protect coastal areas from storm surges that can wash away fragile coastline. Saltwater swamps and tidal salt marshes help anchor coastal soil and sand.

The swamp ecosystem also acts as a water treatment plant, filtering wastes and purifying water naturally. When excess nitrogen and other chemicals wash into swamps, plants there absorb and use the chemicals. Many of these chemicals come from human activities such as agriculture, where fertilizers use nitrogen and phosphorus. Factories, water treatment plants, and homes also contribute to runoff. Chemicals not absorbed by plants slowly sink to the bottom and are buried in sand and sediment.

For most of history, wetlands were looked upon as wastelands, and as homes for insect pests such as mosquitoes. (Swamps are home to a wide variety of insects, which feed on the wide variety of plants.) People thought swamps were sinister and forbidding.

In the United States, filling or draining swamps was an accepted practice. Almost half of U.S. wetlands were destroyed before environmental protections were enacted during the 1970s. Most of the Everglades have been reclaimed as agricultural land, mostly sugar plantations. Draining swampland also created valuable real estate in the San Francisco Bay Area in California.

Federal and state authorities drained much of the wetlands at the delta of the Mississippi River in Louisiana as part of a massive system of river management. When Hurricane Katrina blew in from the Gulf of Mexico in 2005, the spongy swamp that traditionally protected the city of New Orleans from destructive weather patterns was diminished. The city was hit full force with a Category 3 hurricane.

Eradicating swampland also threatens economic activity. Two-thirds of the fish and shellfish that are commercially harvested worldwide are linked with wetlands. From Brazils varzeas, or freshwater swamps surrounding the Amazon River, to saltwater swamps near the Florida Keys, commercially valuable fish species that depend on wetlands are threatened with extinction.

In the early 1970s, governments began enacting laws recognizing the enormous value of swamps and other wetlands. In some parts of the United States, it is now against the law to alter or destroy swamps. Through management plans and stricter laws, people are trying to protect remaining swamps and to re-create them in areas where they have been destroyed.

Vocabulary

Term Part of Speech Definition Encyclopedic Entry

accumulate

Verb

to gather or collect.

agriculture

Noun

the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).

Encyclopedic Entry: agriculture

alligator

Noun

reptile native to the southeast United States and parts of China.

amphibian

Noun

an animal able to live both on land and in water.

biodiversity

Noun

all the different kinds of living organisms within a given area.

Encyclopedic Entry: biodiversity

bird

Noun

egg-laying animal with feathers, wings, and a beak.

civilization

Noun

complex way of life that developed as humans began to develop urban settlements.

Encyclopedic Entry: civilization

climate

Noun

all weather conditions for a given location over a period of time.

Encyclopedic Entry: climate

coal

Noun

dark, solid fossil fuel mined from the earth.

commercial harvest

Noun

agricultural produce sold for profit.

conch

Noun

marine animal (mollusk) with a large spiral shell.

continent

Noun

one of the seven main land masses on Earth.

Encyclopedic Entry: continent

crab

Noun

type of marine animal (crustacean) with a flat body, hard shell, and pincers.

cypress

Noun

type of evergreen tree.

cypress knee

Noun

root growth that sticks up above the water in a cypress swamp.

decay

Verb

to rot or decompose.

diminish

Verb

to become smaller or less important.

duckweed

Noun

type of small plant that floats in great numbers on still water.

ecosystem

Noun

community and interactions of living and nonliving things in an area.

Encyclopedic Entry: ecosystem

eradicate

Verb

to destroy or remove.

Euphrates River

Noun

river in Southwest Asia (the Near East).

Everglades

Noun

vast swampy region flowing south of Lake Okeechobee in Florida.

Fertile Crescent

Noun

region extending from the eastern Mediterranean coast through Southwest Asia to the Persian Gulf.

fluctuate

Verb

to constantly change back and forth.

forbidding

Adjective

scary or dangerous.

fossil fuel

Noun

coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.

freshwater swamp

Noun

wooded area that is at least partially flooded with freshwater for most of the year.

frog

Noun

animal (amphibian) with smooth skin and long hind legs for jumping.

hardwood swamp

Noun

region of hardwood trees, such as oak or maple, that is at least partially flooded for most of the year.

high tide

Noun

water level that has risen as a result of the moon's gravitational pull on the Earth.

Hurricane Katrina

Noun

2005 storm that was one of the deadliest in U.S. history.

insect

Noun

type of animal that breathes air and has a body divided into three segments, with six legs and usually wings.

knob

Noun

rounded bulge.

lake

Noun

body of water surrounded by land.

marine

Adjective

having to do with the ocean.

mud flat

Noun

area left bare by receding lake or tidal waters.

oxygen

Noun

chemical element with the symbol O, whose gas form is 21% of the Earth's atmosphere.

pothole

Noun

deep, usually steep, depression in a natural or man-made surface.

purify

Verb

to cleanse thoroughly.

reptile

Noun

animal that breathes air and usually has scales.

reservoir

Noun

natural or man-made lake where water is stored.

Encyclopedic Entry: reservoir

river management

Noun

the art and science of controlling the flow, path, and power of rivers.

River of Grass

Noun

Everglades, a vast swampy region flowing south of Lake Okeechobee in the U.S. state of Florida.

runoff

Noun

overflow of fluid from a farm or industrial factory.

Encyclopedic Entry: runoff

saltwater swamp

Noun

wooded area near a tidal basin or a protected ocean shore that is partially flooded with seawater for most of the year.

saturate

Verb

to fill one substance with as much of another substance as it can take.

seasonal flooding

Noun

overflowing of a body of water from its banks, usually predicted by yearly rains or storms.

sediment

Noun

solid material transported and deposited by water, ice, and wind.

Encyclopedic Entry: sediment

shellfish

Noun

any aquatic animal that has a shell.

shrub

Noun

type of plant, smaller than a tree but having woody branches.

sinister

Adjective

evil or threatening.

soil

Noun

top layer of the Earth's surface where plants can grow.

Spanish moss

Noun

type of flowering plant with long, fuzzy leaves that droop over tree branches. Spanish moss is not a moss.

spawn

Verb

to give birth to.

storm surge

Noun

abnormal rise in sea level accompanying a hurricane or other intense storm. Also called a storm tide.

Encyclopedic Entry: storm surge

stream

Noun

body of flowing water.

Encyclopedic Entry: stream

swamp

Noun

land permanently saturated with water and sometimes covered with it.

Encyclopedic Entry: swamp

thicket

Noun

small, intensely wooded area.

Tigris River

Noun

river in Southwest Asia (the Near East).

tolerate

Verb

to endure, allow, or put up with.

tupelo

Noun

type of tree native to the southeast U.S.

varzea

Noun

freshwater swamp near the Amazon River.

vegetation

Noun

all the plant life of a specific place.

wetland

Noun

area of land covered by shallow water or saturated by water.

Encyclopedic Entry: wetland

woodland

Noun

land covered with trees, usually less dense than a forest.

Encyclopedic Entry: woodland

For Further Exploration

Websites

Credits

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Writer

Kim Rutledge
Melissa McDaniel
Diane Boudreau
Tara Ramroop
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrator

Tim Gunther
Mary Crooks, National Geographic Society

Editor

Kara West
Jeannie Evers

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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