Louisiana Geography

Geology Geology is the study of how Earth was formed. Scientists who study this are called geologists. They look at rocks, fossils, and land formations to determine how each region of Earth was formed.

Geologists believe all the world’s land mass was connected in one giant supercontinent called… At the end of the Paleozoic Era, Pangaea began slowly drifting apart, this is called An ancient Gulf of Mexico formed between North and South America, covering what is now Louisiana. At that time, the mouth of the MS River would be present day Arkansas!

How was Louisiana formed? Over time, the MS River deposited sediment into the Gulf of Mexico, slowly filling in part of it. As sediment would fall to bottom, the particles created a coastal plain, a relatively low, flat region built up by river sediment. Louisiana is the only state made up entirely by the Gulf Coastal Plain.

Floodplains Floodplains form when rivers can’t handle excess water due to heavy rainfall. Floodplains serve as a reservoir to hold excess water until the river can move it to the Gulf.

Deltas When rivers flow into a large body of water, deltas are often formed. A delta is a landform shaped like a bird’s foot.

Coastal Marshes Coastal Marshes are wet grasslands formed by river sediment deposited along the coast. Coastal marshes can be freshwater, salt water, or brackish (fresh and salt water mixed together). Most of the Louisiana coast is coastal marsh formed by rivers flowing into the Gulf of Mexico. Louisiana has the largest marshland in the United States.

Coastal Erosion Louisiana loses 35 square miles of land a year. The state is literally shrinking as the marsh disappears into the Gulf. On average, an area the size of 2 football fields disappears every hour. What do you think destroyed 64,000 acres in one day?

Coastal Erosion

Salt Domes Part of the Gulf of Mexico once covered Louisiana. When it dried, massive salt domes were left standing. Most are about 10 miles below the Earth. Salt mining is an important industry in Louisiana. Example- Avery Island

Salt Domes

Earthquakes in Louisiana Louisiana experiences frequent earthquakes. Most are small and go unnoticed. In 1964, an Alaskan earthquake caused tidal surges from the Gulf of Mexico all along the Gulf Coast.

Mississippi River The MS River is the fourth largest the world. The river begins in Minnesota and empties into the Gulf of Mexico.

The Mighty Mississippi

Atchafalaya River Atchafalaya = Long River The Atchafalaya River is the longest distributary of the Mississippi River. It flows into the Gulf of Mexico at Morgan City. The Atchafalaya Basin is the largest swamp in the United States. It is estimated that 23 billion pounds of crawfish are harvested per year in the basin.

Atchafalaya Basin

Gulf of Mexico The Gulf of Mexico is our southern border. It greatly affects our environment.

Controlling the Water Levees were built to help control flooding. These levees run along both sides of a river and prevent floodwater from spilling onto the floodplain. Levees solve some problems but create others. For example, during Hurricane Katrina, some levees broke an area flooded rapidly.

Spillways Man created spillways to prevent flooding. There are 2 in Louisiana: The Bonnet Carre Spillway diverts water from the MS River and into Lake Pontchartrain. Morganza Control Structure diverts water into the Atchafalaya Basin.

Spillways