How do deltas form

The ecosystem what was once the world's largest desert estuary has been reduced to a fraction of its former area, and many indigenous species are vulnerable, threatened, or endangered. Finally, decades of river management prevent the Mississippi River from naturally flowing through its delta wetlands. Like the Nile delta, the Mississippi delta is also eroding. This situation contributed to the devastation caused by Hurricane Katrina in Delta Blues Delta blues is a style of music developed by African-American artists living and performing in the Mississippi Delta region of the southern United States.

The Mississippi Delta is actually a flood plain between two rivers in northwestern Mississippi, the Mississippi and the Yazoo, it is sometimes to as the Yazoo-Mississippi Delta. Slide guitar is one of the standard instruments used by delta blues musicians, while familiar topics include poverty and injustice.

Robert Johnson, widely recognized as one of the greatest guitarists of all time, played the Delta blues. Listen to Robert Johnson here. Also called an alpha predator or top predator. Also called a birdfoot delta or bird's-foot delta. Usually rivers enter another body of water at their mouths. 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.

Jeannie Evers, Emdash Editing. Caryl-Sue, National Geographic Society. For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher.

They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource. If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media. Text on this page is printable and can be used according to our Terms of Service. Any interactives on this page can only be played while you are visiting our website.

You cannot download interactives. Search through these resources to discover more about unique landforms and landscapes around the world. Landforms are natural and distinctive features. Explore how they show up in various landscapes. These resources can be used to teach middle schoolers more about the natural world, its distinctive features, and landscapes. Of that, only about 1.

Most of our drinking water comes from rivers and streams. This water is the lifeline of ecosystems around the world. Freshwater is a precious resource on the Earth's surface. It is also home to many diverse fish, plant, and crustacean species. The habitats that freshwater ecosystems provide consist of lakes, rivers, ponds, wetlands, streams, and springs.

Use these classroom resources to help students explore and learn about these places. A biome is an area classified according to the species that live in that location.

Temperature range, soil type, and the amount of light and water are unique to a particular place and form the niches for specific species allowing scientists to define the biome. However, scientists disagree on how many biomes exist. Some count six forest, grassland, freshwater, marine, desert, and tundra , others eight separating two types of forests and adding tropical savannah , and still others are more specific and count as many as 11 biomes.

Use these resources to teach middle school students about biomes around the world. A habitat is an environment where an organism lives throughout the year or for shorter periods of time to find a mate. The habitat contains all an animal needs to survive such as food and shelter. A microhabitat is a small area which differs somehow from the surrounding habitat. Its unique conditions may be home to unique species that may not be found in the larger region.

Unfortunately, some habitats are threatened by pollution, extreme weather, or deforestation. This puts many of the species that live there in danger and is causing many populations to decline. Explore different types of habitats and microhabitats with this curated collection of classroom resources. Use this map to help students learn more about the Okavango Delta in Africa, including how it was formed and why it is important to the people and wildlife of southwestern Africa. Join our community of educators and receive the latest information on National Geographic's resources for you and your students.

Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Types of Deltas There are two major ways of classifying deltas. Influence There are four main types of deltas classified by the processes that control the build-up of silt: wave -dominated, tide -dominated, Gilbert deltas, and estuarine deltas.

Deltas and People Deltas are incredibly important to the human geography of a region. Disappearing Deltas Extensive river management threatens deltas. The triangle-shaped Nile Delta is a perfect example of an arcuate delta. These distributaries appear like a maze of water channels.

A fast and turbulent river transports larger sediments in size and amount. This cycle continues producing beds with alternating layers of fine and course sediments. Deltas are mistaken for another classification of land form called alluvial fans. Alluvial fans are also composed of fan —shaped layers of sediments. The terms however are not interchangeable as delta is mainly formed beside a river or a body of water while alluvial fan formation happens on dry land. The three main types of deltas are the arcuate, the bird's foot and the cuspate.

The arcuate are the fan-shaped deltas. The wider portion of the fan is facing the water. Relatively coarse sediments are formed in this type of delta. The river activity is balanced with the wind. This shape is created when the waves are weak and the river flow is stronger. Thus, this delta rarely occurs along ocean coasts because the waves are often stronger than the river current. The cuspate deltas are formed where sediments are deposited onto a straight shoreline with strong waves.

The waves push the sediments to spread outwardly creating the tooth-like shape. National Geographic Learn more about deltas at this interactive page that features photos from around the world. Vancouver Sun An article about the high costs projected for flood protection measures in the Lower Mainland area of British Columbia.

Search The Canadian Encyclopedia. Remember me. I forgot my password. Why sign up? Create Account. Suggest an Edit.

Enter your suggested edit s to this article in the form field below. Accessed 13 November In The Canadian Encyclopedia.

Historica Canada. Article published February 01, ; Last Edited November 03, The Canadian Encyclopedia , s. Thank you for your submission Our team will be reviewing your submission and get back to you with any further questions. Thanks for contributing to The Canadian Encyclopedia. Article by Alan V.