Tuesday 4 October 2011

Sometimes you don't need colouring pencils in Geography!

Recently, I have encountered some who have dismissed Geography as a science and have stated that it's what you do if you like colouring in! Well, here's a message to those people: sometimes, it's already coloured in!
The Earth is commonly referred to as the 'Blue Planet' but zoom in and you'll find black and white sands, red and green sandstone, multicoloured minerals and rocks that even change colour to the light! It's actually quite a colourful planet!

The colours of rocks are most often or not determined by minerals: iron is red and brown, copper stains green, with Sulphur, however, it's yellow. Desert rocks are coated in what's known as "desert varnish" (actually iron and manganese oxides). Sometimes, the colour is determined by living organisms: green algae and yellow lichens. Even antartica is not always white: sometimes, the snow can be coloured pink by snow algae. For any water system, such as a sea or an ocean or even a pond, the colours that they appear to be are influenced by the sediments that pour into them.


One of the most fantastic examples of 'colourful Earth' is Ayers Rock which actually changes colour every day. And it's all to do with the light! It's based in the Northern Territory of Australia and throughout the day as the light intensity that shines onto it changes, so does the rock colour. One of the main reasons for such a change is because it's constructed out of different types of rock: it's actually an inselberg that has been shaped by wind blown sands!

You and I probably think of yellow quartz when we imagine sand dunes, but in New Mexico, on the broad and flat floor of the Tularosa Valley, the dunes are made up of gypsum which is almost pure white in colour.




Holiday Brochures often advertise "golden beaches" but on the 'Canary Islands' the littoral zone is made up of dark coloured basaltic rocks! The Canary Islands are actually cones produced by extinct volcanoes.



The Black sea is not actually black nor is the White Sea actually white, but there has to be a case made for the Red Sea. Sometimes, tiny red marine organisms known as Dinoflagellates reproduce in a mass colouring the entire sea red. Red tides as they are known are very dangerous; they even caused the death of about 50 million fish in 1946.


1 comment:

  1. Dear Daniel Evans,
    As an active reader of your blog and an amateur geographer myself, I would like to point out that the volcanoes in the Canary Islands are still quite active and are not yet extinct.
    Also in your first paragraph, there's a grammatical error in your last sentence.

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