February 05, 2015

Agenda

1. Go over Chapter 9 Test

2. PowerPoint titled: The Active River

3. Possible Video

Come in Quietly and sit at your desk with your thumbs up. Make sure your science notebook is out and open to the next blank page.

Subject Area: The Active River

EQ: What is the dominant process in shaping the landscape in California?

Questions:

1. What is the Water Cycle?

2. What is a drainage basin?

The Active River

About 6 million years ago the grand canyon was very flat. The Colorado river cut into the rock to form the Grand Canyon by washing billions of tons of soil and rock from its riverbeds.

Erosion

Erosion is the removal and transport of surface material, such as rock and soil. Wind, rain, and ice can cause erosion as well as a river.

Water Cycle

Have you ever wondered how a river will keep flowing? The Water Cycle is the answer. The Water Cycle is the continuous movement of water from water sources, such as lakes or oceans, into the air, onto land, into the ground, and back to the water sources.

Partner Question:

1. How does the water cycle help to develop river systems?The water cycle helps develop river systems by …

Water Cycle

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River System

A river system is a network of streams that drains an area of its runoff. An area will get saturated and have an excess of water. The water will then start to run off creating a gully. With each passing rain it will eventually be a river.

Drainage Basin

River systems are divided into regions known as drainage basins. Drainage basins is the land drained by a river system and all of its tributaries. The largest drainage basin is the Mississippi river basin.

Partner Question:Describe a drainage basin. A Drainage Basin is …

Tributaries

Tributaries are smaller streams or rivers that flow into larger ones. The Ohio and Missouri Rivers are two of the tributaries of the Mississippi River.

Divide

Drainage basins are separated from each other by an area called a divide. A divide is generally an area of higher ground than the basin it separates.

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Stream ErosionWhen a stream first forms, the water cuts

downward, eroding soil and rock to create a channel. A channel is the path that a stream follows. At first, stream channels are small and steep. As more rock and soil are transported down stream, the channels become wider and deeper.

Rates of Stream Erosion

The rate of stream erosion is determined by various factors, including the stream’s speed (gradient), discharge, and load.

Gradient

One factor that can affect the speed of a river is its gradient. Gradient is a measure of the change in elevation over a certain distance.

Discharge

Discharge is the volume of water transported by a stream in a given amount of time. The discharge of a stream increases when a major storm occurs or when warm weather rapidly melts snow. During a drought or dry season it will decrease.

A Stream’s Load

The materials carried in a stream’s water are collectively called the stream’s load. The size of the particles in the stream’s load is affected by the speed of the stream.

Partner Question:What are three factors that affect the rate of stream

erosion?The three factors are …

The Stages of a River

William Morris Davis developed a model that identifies the stages of river development. According to this model, rivers evolve from a youthful stage to an old-age stage.

Youthful Rivers

A youthful river erodes its channel deeper rather than wider. The river tumbles over rocks in rapids and waterfalls. Youthful rivers have few tributaries.

Mature Rivers

A mature river erodes its channel wider rather than deeper. It is fed by many tributaries and has more discharge than younger rivers.

Old Rivers

An old river has a low gradient and extremely low erosive power. The river deposits sediment in the channel and along its banks.

Rejuvenated Rivers

An old river has a low gradient and extremely low erosive power. The river deposits sediment in the channel and along its banks.

The land will shift causing a greater gradient and the river will flow faster, cutting into the rock again.

Partner Question:

How do youthful, mature, and old rivers differ?These rivers are different because …

Land and Water Erosion

Summary

1.Answer the essential question “What is the dominant process in shaping the landscape in California?”

2.Your answer needs to be in complete sentences.3.Place your answer at the bottom of the notes we

did today. 4.Make sure you include how the water cycle is

involved in the constant flow of rivers. 5.Use your notes to get the answers.

Class Work

Chapter 10, Section 1 in the purple workbook. This is found on pages 73 – 75.