Now to teach you this, I would like a little bit of “audience participation”. I will give you a few very general uses of rivers and I would like you all to give my examples under each category. You can post your answers under the reply section to this blog.

Here goes:

Recreation:

Source of food:

Transportation:

Industrial uses:

Domestic uses:

If you can think of anything else, please let us know. Thank you so much and we hope we have helped you learn something about river's and coasts.

Okay I know that you people are tired of rivers. Therefore as a very good teacher, I have decided to teach you about......drum rolls please? Okay I am going to teach you about coasts, not rivers. Happy? Ha! Today I am going to teach you about the landforms produced by coastal processes. The landforms created by the rivers is determined by coastal processes mainly three coastal processes…erosion, transportation and deposition

Firstly, we have the cliff. A cliff is a high, steep rock face along a coast. Cliffs are found in many high places in the world.

A cliff is formed when waves rapidly pound against a rocky coast. Due to the constant pounding of water against rock, the rock beings to weaken and weaken and weak... Over a long, long time it will be eroded into a cave and then after another long, long time, it becomes a cliff. Why? You may ask, because of the constant pounding every day, every minute, probably every five seconds. The cliff erodes more and more and retreats inland. A shore platform soon develops. I if you look at the whiteboard section of the blog, there is a picture of the shore platform.

Next are the headlands and bays. Now I have already taught you that different types of rocks erode at different speeds, haven’t I? The different rates of erosion results in the uneven erosion of coasts. The less resistant rocks get eroded away retreating inland and that forms a curve which is called a bay. (I know that this is not so easy to understand but if you look at the picture called headlands and bays in the whiteboard section you will understand it better.) The headland is the part sticking out in between two bays.

Moving on to beaches, I am sure you have been to a beach before, or at least seen one in pictures. Beaches are just accumulations of sediments on the coast. Waves carry little sediments when they come on the shore but when they are receding, they lose their power and leave whatever they were carrying on the shore. This is why there is often a row of particles like shells and stones on the beach when you walk close to the water. Different currents sweep in different things. A beach could be made of small rocks and gravel. This would be a steep beach because the backwash won't be strong enough to pull the rocks back in. in comparison, a beach made up of sand would be gentler because the backwash would pull some of the sand particles back each time. Beaches have no fixed shape. The shape is determined by the current. If there is a really strong current, the beach will erode fast but if the current is gentle, it will build up the beach because it will deposit more particles on the beach.

Lastly, we will learn about spits and tombolos but before we learn this I would like you to familiarise yourself with the term long shore drift. Please refer to the picture we have drawn under the white board section...

Now that you have done that, we can start. The longshore drift drags sediments, usually sand, with it when it moves along the shore. Where the direction of the shore turns inland the longshore current spreads out. No longer able to take the full load, much of the sediment is dropped. This causes a bar to build out from the shore, eventually becoming a spit. If the spit extends to join with an island, it forms a tombolo.

There you ... you're all done. Wasn't that fun. Congratulations on getting this far. Hope you enjoyed yourself.

Let's go straight into the learning this time, shall we? I will explain what the different landforms are and how they are formed.


Waterfalls: Now, everyone knows what waterfalls are. In case you don't, you can refer to the "photo" section of the blog under "lesson 3". To understand how waterfalls are formed, you need to understand that water doesn't always flow over the same terrain. When it flows over less resistant rock, it erodes it quickly but it takes a longer time to erode a more resistant rock. It keeps eroding the less resistant rock under the more resistant rock erodes faster and changes the gradient of the river course. The water falls off this with a really strong force and eventually a huge hole forms from the impact. This hole is called the plunge pool.

There is another way that waterfalls are formed too. Waterfalls could be formed by faults in the earth. When one rock is higher than another because of the displacement of the rocks, the water flows over them. The water plunges from a height and creates a plunge pool. An example of a waterfall that is formed this way is the Victoria Falls.

Now we move onto gorges. While doing my research, I came across this wonderful site and I will be making use of one of their illustrations to explain the formation of gorges. Just open the following link in a new window.

http://www.school-portal.co.uk/Group...

Gorges are also deep, narrow and steep-sided opening between upland areas, usually containing a river. Gorges are formed when very powerful rivers cut across very resistant rock. Isn’t that easy to remember? 

Moving onto *drum roll* valleys. Valleys are low laying areas in between hills or mountains different rivers erode the valleys they run through differently. The upper course of the river tends to be quite strong because of the gradient of the slope and hence can erode the rocks better forming a v-shaped valley.

The middle course tends to be gentler. The river has less energy and doesn’t cut as deeply into the channel. The sides of the valley tend to be wider here than in the upper course.

In the lower course, the valley is far wider than the upper and middle course of the river because the gradient of the land is gentle. The valley here is usually broad and flat.

Moving onto floodplains. Let’s group this with levees because they are related. You’ll see how in a while… Flood plains are formed when a river overflows due to heavy rain and the water spreads out over the surface of the land and causes the river to “temporarily expand”. When the water recedes, it pulls in sediments from the land and deposits them along the river bank. The finer sediments are deposited further from the river and the coarser sediments pile up along the banks of the river forming levees. These are usually found at the lower course of the river. Alluvium that is deposited along the floodplain is very fertile.

Let’s go onto meanders now. This may feel like a real handful but relax. You can take your time to learn all this. Meanders are formed by a mixture of erosion, transportation and deposition along the river. As the water flows down a river, its speed is faster on the outside of the meander causing erosion and slower on the inside of the meander resulting in deposition. The outside keeps getting eroded and the inside collects everything and the bends in the river get more distinct.

Moving on to Oxbow lakes. Sometimes, meanders become very distinct and with all the erosion of the banks, two meanders move closer together, forming a loop. Eventually, this loop becomes more and more distinct and gets separated by a narrow line of land. The deposition and erosion continues and an obvious ring is formed. The sediments will create a dam like structure trapping the water into the oxbow lake. This lake will dry up in due time and will support the growth of plants.

Before I let you off for a short