River Landforms

We have moved on from rivers to river landforms!

We started the lesson (21 April 2011) with a recap of what we have learnt the previous lesson,
which is, what is erosion (a process of wearing down), transportation and deposition (the dropping of sediments in order to regain back energy). Among all theses processes, erosion takes up the most energy. We then went on to answer the question Ms J asked us in the previous lesson, 'How do you think waterfalls, valleys, floodplains, deltas, distributaries and meanders are formed?' We started with waterfalls first. Ms J told us to try and see if we knew how they were formed. After a while, Chrystal, Nicole and I came up with an answer. We knew it has something got to do with erosion. Our explanation- it was a slope at first, then as the water flowed down, the water erodes the sides. To help you understand what we had in mind, check out a drawing I 'drew':Blue-water, brown- original slope, purple to yellow- process, green- now

I thought it was quite an explanation. However, like always, geography isn't easy and clear-cut. It turns out that the correct explanation is:

Okay, so it's like this- believe it or not, it is actually a rock at first. Not just any rock, though. It has to be a rock with different layers, soft and hard. Yes, there is such a thing. Anyway, the water erodes the rock. Obviously the easiest to erode is on the soft rock layers. so it erodes and creates what you see in the diagram. There are some parts that are missing, though. Do you know where is the plunge pool, overhang and notch are? Yes, the plunge pool is the place where there is what looks like a swimming pool under, in the diagram, the place labeled soft rock layer. The overhang is the point which the watyer flows down, and the notch is the place where, in the diagram, seems 'untouched' by the falling water.Cool, right?

I found interesting websites while doing my research, and they are relevant to geography. Check them out!

• http://www.factmonster.com/ipka/A0770414.html

• http://www.world-of-waterfalls.com/

All the best for the upcoming Common Tests!

More About The Water Cycle

In term 2 week four, Miss J explained a bit more about the Hydrologic cycle. Before that, I will point out the processes that get involved in the Hydrologic cycle. First, Evaporation, Transpiration, Condensation, Precipitation, Interception, Infiltration, Surface Run Off and then Ground Water Flow. Interception, Infiltration, Surface Run Off and Ground Water Flow are new terms to us. Moreover, we will explain more about them. For Interception, it is the flow of water down the leaves, trees, branches, trunks or even houses and it is actually the process in which an obstacle prevents the water to flow directly down to Earth. For Infiltration, it is the process in which water permeates through the ground. This also has a link to the next term we have been introduced to, Surface Run Off. Surface Run Off is where the water flow on the surface of the ground. The speed of the flow can be determined by the steepness of the slope. If the slope is steep, the Surface Run Off will be faster, therefore leaving lesser time for the water to infiltrate into the ground, hence, the plants are unable to absorb much water. If the slope is quite gentle, the result will be vice versa. However, the rate of the infiltration is also affected by the permeability of the soil. How about Ground Water Flow then? It is the process where water flows under ground. The MAIN thing that keeps a river flowing will be ENERGY. As long as the river has energy, it will still continue to flow. One main misconception that Miss J had told us about will be that students always think that rivers MUST AND ONLY flow from highland when a river can also flow from lowland as it has energy. The speed of liquid is called vilocity. To compare a relationship, we must have at least two variables. To have a direct relationship, if the volume of the river increases, the energy will also increase. However, if the volume of the river increases but the energy decreases it is called an inverse relationship. All rivers try to achieve a process called EQUILIBRIUM. It is a process in which a river tries to have just enough energy to flow. If it has too much energy, it will find ways to get rid of it. If it has a weak flow, it will try to deposit the sediments it contains so that it has more energy to flow. Three main factors that affect the river's amount of energy will be firstly, the gradient of the slope, obstacles, (e.g. trees, rocks) or the amount and size of sediments. The amount of river energy allows it to cause EROSION, TRANSPORTATION AND DEPOSITION. Moreover, water shape landforms as well, which links back to our previous topic, Landforms. Did you know? Waterfalls are also part of the river system. In fact, it is quite big. Some examples will be the Victoria falls, Nigera falls. The path the river flows through is called the river channel. There are parts to a river system. There is the beginning, where it is known as the upper course, then there will be the middle course, lastly there will be the end, which is also known as the lower course. Other parts to the river system will be the tributaries, confluence and the river mouth. They are also new terms introduced to us. The tributaries are lakes or rapids. They all meet up at the confluence, the point where they meet. Then, they will all flow through the main river channel. After the lower course, the channel will end at the river mouth, where the river opens into the ocean. To sum it up, the river system is a body of water. Next, we learnt about the drainage basin, it is the land area that the river system lies in. And the watershed is an imaginary boundary that separates one drainage basin from the other. Did you know? River can flow from lowland to uphill as well. However, we still cannot find which river is it that has this amazing feature. Can anyone tell us?

In the third week

I just want to add on to what to the previous post that we learnt some things new in the third week. Miss J had done a short revision with us about landforms to round up this topic and we covered the basic topic of physical environment again. There four components to the physical environment. Do you know what are they? They are landforms and rocks, rivers and lakes, weather and climate, and natural vegetation. We need to understand that there are interrelationships between these components. She revised that other than creating volcanoes, when plates converge, they can also create fold mountains. A fold mountain is formed when ssome of the layer of rock which make up the Earth's crust buckle and form folds. They are found in the Himalayas, the Appalachhian Mountains in North America, the Andes in South America and the Alps in Europe. Talking about mountains, we all know that they are part of landforms, but do we know the others? The others include:

A Hill, an area of high ground, usually less than 600 metres high. It is typically rounded in shape and has gentle slopes.

A Valley, also known as a depresion, is a low area of land between hills or mountains.

A Plain, a broad flat and low area of land.

Plateau is a generally raised area of land with a fairly flat, braod top and steep slopes.

Furthermore, Miss J also introduced briefly on our next topic. Riverss and Environments. Do you know? 97% of the water on the Earth's surface is salt water and the rest will be fresh water. She also introduced the term HYDROLOGICAL CYCLE to us. The cycle consists of several processes.

The next 2 weeks...

This blog post is summarising what we have done for the last 2 weeks' lessons. Basically, Ms J told us that we were to become little teachers- we had to teach the class one topic that Ms J gave us. Here is the list:

1. Alison and Corrine- Internal and External Forces

They taught us using a powerpoint. I have summarised all that they have taught us (or at least what I have written down!), the magma forms under the volcano, then goes up the main vent. The magma pushes towards the crust and goes up the volcano (I guess this is where the 'internal forces' come in), and as I goes up, it becomes hotter. As it is rising, it becomes lava too. The lava can come out of the volcano slowly (as in flow down) or very fast. As the lava cools at an intense heat, it becomes Igneous rocks. That was all that I took down, and it isn't little either! I think they did a great job!

2. Us, Chrystal and Joanne- Distribution of Volcanoes

We also taught using powerpoint slides. If anyone wants the slides, please do not hesitate to tell me, and I'll email you ASAP. Anyway, here is the summarised version of our 'lesson'. Volcanoes are located at the margin of tectonic plates especially in subduction zones. They can be located at hotspots too. Tectonic plates are massive, irregularly shaped slabs of solid rock. Hotspots? They are fixed places within the mantle or oceanic lithosphere. Indonesia has the most number of volcanoes as Indonesia sits on the Ring of Fire. Did you learn anything special that day? :)

3. Esther and Jessica, Nicole and Cherie- Effects and Impacts

I decided that if I summarised these 2 groups together, it would be easier. Esther and Jessica used powerpoint slides while Nicole and Cherie used the board. So, in volcanic eruptions there are long and short term effects. There are positive and negative effects too. Long term effects are hazardous, because they can cause trouble such as lahars, which is mud mixed with lava. They can cause floods, if I am not wrong. For the positive effects, the lava and ash breaks down into sediments which are nutrition to make the soil fertile. However, there are negative effects, too, such as the ash the was erupted could cover the sun, making it dark and causing breathing difficulties for the people. All these link to the factors of an eruption. The factors are:

• quantities of lava, ashand tephra (volcanic materials) released


• how loud the eruption is


• amount of gas released


• the viscosity (Ms J compared water to honey. High- slower, like honey, low- fast, like water. It really worked. Honey is thicker and more concentrate than water. The level of viscosity shows the ability of the materials, and it measures a material's resistance to flow.)

4. Matthea, Natalie and Mildred- Types of volcanoes

They used the white board, and they were so thoughtful to print out the notes for us. It helped a lot. How come never I've thought of itt before? Anyway, the summary. The parts of a volcano are the pipe (conduit), the vent (the opening that the pipe leads to). There is also the crater ( the depression, a bowl-shaped opening), the magma chamber/reservoir (where the magma is stored), the flanks (which is the sides of a volcano), summit (the highest part of the volcano), the ash cloud (made up of powdered rock and lava), and, of course, the lava (magma that has reash=ched the Eatrh's surface). There are 3 different types of volcanoes- Shield volcano, Composite volcano and Cinder Cone volcano. They all have different characteristics.

After everyone has presented, Ms J recapped and then went on to the next topic, whch is rivers. I'll bet this is going to have to do with a little bit of History (because the Cradle of Civilisation is always beside rivers. Wait, have I gotten my facts wrong?). Ms J said that it might clash with what we have learnt in science. I am all prepared to take up the challenge, though, and see what does Geography have to say about rivers!

Past three weeks

In the first week of term one, Joanne and I presented our powerpoint on the distribution of volcanoes. The following will be what we had said in the presentation.

Well, what is the distribution of volcanoes then? It is volcano activity that happens to be concentrated in specific locations. Where do we usually find volcanoes? They are most likely located at plate boundaries(also intepreted as the edges of tectonic plates), especially at subduction zones. Moreover, volcanoes can also be present at hotspots(also intepreted as mantle plumes). Talking about hotspots, do you know, although Hawaii is not near any plates, it still has quite a number of volcanoes on the island. It is because the hotspots that occur below will cause volcanoes to form when the plate that Hawaii is part of moves past the hotspots below. However, the largest and most lethal volcanoes usually form at plate boundaries. What about Tectonic plates and hotspots?

Tectonic plates(also called lithopheric plates) are massive, irregularly shaped rocks. They are generally composed of both continental and oceanic lithospheres. The plates' sizes may vary greatly, from a few hundred to thousands of kilometres across; the Pacific and Antartic plates are among the largest. Most of the boundaries between individual plates cannot be seen as they are hidden beneath the oceans. Hotspots are far from the edges of the tectonic plates. They are fixed places within the mantle or oceanic lithosphere. They are then broken up into plates, where rocks melt to generate magma. When hotspots are situated in the oceanic lithosphere

a class of volcanoes known as shield volcanoes is built. These are constructed on the deep ocean floor and may be built high enough to rise above sea levels as volcanic islands. The definition of the LITHOSPHERE is the outer shell of the Earth which is made of the Earth's crust and the outermost layer of the mantle.

Indonesia has the most number of volcanoes. It has more than 160 active volcanoes. Why? Indonesia sits on what we call the Ring of Fire and the Ring of Fire is a zone of frequent seismic (relating to volcanic activity) and volcanic activity around the rim of the Pacific Ocean. Lets see the picture below that shows a volcanic map of Indonesia.