Geography At The Movies

I was directed to this website by a teacher who I observed recently. It does not contain any concepts regarding deserts but I thought it would be a good idea to display it in case other people had not seen it before. It contains a collection of videos, both professional and amateur linked to different topic areas in geography and which can very easily be included into lessons.

http://www.gatm.org.uk/

If you get chance have a quick look and see what you think.

Dunes

As I have previously mentioned, desert landscapes are indeed unique and owe their characteristics to the weathering and erosion processes which occur.

One aspect which I did not talk about in detail is abrasion. The process of abrasion can be compared with the effect of sandblasting a building. Wind carries sediment in suspension and ‘blasts’ it against the rock usually wearing it smooth. In desert environments it wears away layers of soft rock close to the ground surface resulting in spectacular pillars of slightly more resistant rock. Monument Valley, which spans the border of Utah and Arizona in the USA, is an excellent example.

Of course we cannot discuss desert landforms without mentioning dunes. This would be the first image that many students will associate with deserts and as such, they cannot be ignored. Dunes typically form in sandy deserts where the wind is strong enough to transport material and the surface is subsequently moulded into dune shapes. There are various different types of dunes and the strength, direction and consistency of wind all play an important part in what type of dunes will be formed.

Wind does not flow in a uniform pattern. It meanders and eddies, moulding the surface into a shape which follows the path of least resistance. The most common dune studied is probably the barchan. As shown in the picture these are crescent shaped and can reach heights of around 30 metres. It is important to note that these dunes are not fixed but they migrate in the direction of the wind. The diagram below attempts to explain this.

Dunes move as sand on the windward slope is carried over the crest and deposited on the slip face where the wind slows and therefore cannot carry its load due to a lack of energy. There are other types of dune that need to be discussed such as parabolic, transverse and longitudinal there are even more but we are probably becoming too complicated if we go any further.

Once the basic concepts of dune formation have been taught they students could be given a group exercise and attempt to describe the formation of the above dunes (parabolic, transverse, and longitudinal) based upon the information already provided. Their answers could then be discussed with other groups within the class and either confirmed or rejected. Group exercises allow for ideas and information to be processed on a larger scale and allow for a contribution from all students in the class and not just those who volunteer to answer questions.

Desert DNA

Desert landforms are unique in their structure and their formation. For these landforms to exist, other factors must first be discussed. Weathering and erosion must occur to allow for the movement and transportation of earth and sediment which form the desert landscape.

For many years it was believed that the dominant process involved in desert weathering was the mechanical breakdown of rocks due to the cycle of heating and cooling in the extreme environment. Commonly known as exfoliation or onion-skin weathering the daily variations in temperature stressed the rock causing it to fracture on the surface with the outer layers subsequently being ‘peeled’ away. More recent studies have identified that this particular method of weathering is not alone responsible for creating desert landscapes.

It is now commonly accepted that wind and water are also important processes, and led to the distinction that different processes are dominant in different areas. It became clear to scientists and researchers that areas which are typically very dry may have experienced a much different climate in history. Wind erodes the landscape through deflation and abrasion and transports the eroded material in several ways, including saltation, suspension and surface creep, similar to the processes found to occur in a river channel.

It would be important to notes to students that not all desert landscapes are the same and it would be interesting to begin a lesson by displaying a selection of photos of desert landscapes and asking students which they thought were deserts and which were not, emphasising that a desert landscape is not restricted to camels and sand dunes. Case studies such as the Grand Canyon (a deep gorge) and Death Valley (being immensely flat) in the US could be introduced. The Grand Canyon would be a great example of water erosion and how over a large time period the landscape can change dramatically. Case studies are an excellent way to place ideas into reality and students can only benefit from doing this.

Sand, sand and more sand

Deserts are physical phenomena that I have never really studied, apart from a brief overview in my Geology A-Level and seeing as though estimates show that they cover between 14-18% of the Earth's land surface, I thought it'd be wise to broaden my knowledge regarding them.

It is clear that deserts are intimately linked with other physical geography topics such as climate. Their formation is directly influenced by the circulation patterns that occur between the tropics. Subtropical areas typically have constant high atmospheric pressure due to the descending air of the Hadley cells. These conditions prevent moisture bearing clouds from forming and therefore lead to dry, arid conditions. The short video below provides a very simplified version of this.

http://www.youtube.com/watch?v=DHrapzHPCSA&feature=related

Whilst teaching it will be important to ensure that pupils are aware that the term 'desert' is not restricted to hot, arid areas such as the Sahara. Some scientists argue that large tundra areas such as the Antarctic can also be classified as deserts as they receive very small amounts of precipitation and a largely uninhabitable.

It would also be of benefit to possibly begin introducing this topic by asking students what they already knew about deserts, their locations, features etc as these ideas could either be confirmed or challenged through the later teaching, opening up further avenues of thought for the students to develop a greater understanding.

A brief introduction to deserts would lead nicely onto the processes that occur within deserts and the features that are formed as a result.

The Subject Knowledge Audit

Before completing the subject knowledge audit and after a two year absence from any resemblance to academia I thought that I'd spend most of my time circling the lower numbers. I was pleasantly surprised to find that this was not the case as the geographical part of my brain sputtered back to life. I have uncovered topics which I'm not too clear on and therefore they are the areas on which I will concentrate in this blog.

It was also interesting to discover that my weak subject areas were not confined to just physical or human aspects and seemingly a balance has been struck. The areas which I will discuss and attempt to break down into manageable sections which could be presented to students, are ones which I have had little contact with myself. These concepts have either been overlooked at University level or omitted at GCSE and A-Level.

In brief, the areas which I will be discussing are:

• Extreme landscapes, deserts in particular.
• Ecosystems
• Cultural geographies
• Weather and climate, concentrating on air masses, depressions and lapse rates

Hopefully the ideas which I present will challenge student's knowledge of a topic and allow them to develop a deep understanding of the key concepts with the aim of leading to a greater learning experience for all.

The Difficult First Post

I guess an introduction is the best way to begin a blog like this so first things first.

Geography and teaching are in my blood. This is mainly due to the fact that both my parents are teachers with my dad specialising in geography. Useful you may say, however it has given me a detailed preview of how intense the next 12 months will be. A year which I approach with great anticipation and excitement.

I graduated two years ago and as a result I had plenty of time to consider my future. No matter how many times I discussed ideas with family and friends the result was always the same. It seemed like fate was drawing me towards the PGCE. Now I'm here with just over three months left of freedom, which I'm going to enjoy whilst I can, though working full time and cramming as much overtime in as is humanly possible is restricting this to some extent.

I hope that this blog will identify areas of my geographical knowledge which need refreshing. It will also allow me to begin to get an idea of exactly what resources are available and identify useful websites and literature. Until next time.......