The student will do the following:

1. Learn about common sediments (stream sediments), sediments of the continental shelf, deltaic sediments, offshore sediments, and apply the knowledge to the Mississippi River.

Geology of the Mississippi River, Communication, Group work

2 class periods

Sediments that are formed through physical weathering will eventually end up in the ocean. Physical weathering is the breakdown of rocks by mechanical means. These sediments may travel and rest in a number of different places until they reach the ocean. Below is a picture of the many different places sediments may travel through.

The sediments may stay in any one area for a long period of times, but they will eventually end up in the ocean. We will focus on what happens to sediments as they travel through the Mississippi River. We will study the effects the stream and the continental shelf (the delta, and offshore areas) have on sediments.

-Streams are the major process by which sediment is moved across the land.

-The sediment will differ from place to place because of the type of stream, how fast the water flows, and the type and the size of the sediments.

-For example:

-A typical large, smoothly flowing stream will deposit well-sorted layers of large and small particles

-Small sediments such as silt and clay will be laid down next to the stream during floods

-The faster the flow of water in a stream, the larger the size of the sediments will be carried. As the water slows down, the larger sediments will be deposited first, until only the tiny particles, such as silt or clay, are left.

Once the sediments reach the mouth of the river, they can accumulate near the streams. From that point onward, the ocean can move them. Quite a lot of sediment accumulates on the continental shelf. There are several types of continental shelf sediments. The ones that we will be studying are deltaic sediments, estuarine sediments, and offshore sediments.

When a large stream, such as the Mississippi River reaches lands end, the velocity and the ability to transport the sediments suddenly decreases. What results is a delta. In general, the delta looks like a big fan. The river fans out into several different smaller rivers.

A marine delta builds outwards onto the sea. Large deltas, such as the Mississippi River Delta are very complex. Different types of sediment deposits characterize different streams of the delta. There may be large sediment deposits in one stream, small in another, and even finer still in another stream. For a delta to occur, sea level and the land must not be very different from one another.

Freshwater from a stream can continue to flow into the ocean. As a result, sediment in the stream will be carried along with it. This type of sediment will be very fine-grained (tiny) and suspended in the water. The tiny sediment can be deposited onto the outer-shelf and onto the seafloor. Offshore sediments compose about 70% of the sediment found on the continental shelves. Only 10% of the sediment reached the deep ocean. This means that the continental shelf is continually being conserved.

1) Split the class up into three groups and assign each group one of the following topics: Stream sediments, Deltaic sediments, and Offshore sediments

2) Each group will read about their assigned topic and then report to the class (during the next class period) about what they learned, and how their specified topic relates to the Mississippi River.

3) After the presentations, have the class answer the questions asked below.

1) What is a method where sediments are formed and where do they end up?

2) What is the main way in which sediments reach the ocean?

3) What happens to the sediment being carried in the stream as it begins to slow down? What type of sediment will be affected first?

4) What does a delta look like, and how does it form?

5) What types of sediment deposition can be found in a delta?

6) What types of sediment make up a continental shelf?

7) Why do you think it is important that the continental shelf should be continually conserved by sediment?

8) What do you think would happen if the continental shelf did not exist? Use the state of Louisiana as an example.

9) Can you name other river systems aside from the Mississippi River that has this type of sediment deposition?