Plate Tectonics - the basics...

Seeing as we have just started vulcanicity, I thought it would be a good time for me to re-cap on what we should have learnt so far (we have covered quite a lot of new stuff, especially for non-Geologists such as myself, so this will probably have to be written over a series of posts)......

First up, we need to have a basic understanding of the evidence that exists which supports the theory of plate tectonics. As simply as it can be put, we have older evidence and newer evidence.

Older Evidence:
- Biology - same fossil formations found in different parts of the world
- Geology - rocks of same afe and type and displaying the same formations found across the globe. Similar glacial deposits are found in Antarctica, South America and India, now many thousands of kilometres apart; striations showing the same orientation when the continents are reunited, are found in Brazil and West Africa.
- Climate - fossils of plants that live in tropical conditions found in Antarctica, with it incredibly unlikely that tropical climatic conditions ever existed in Antarctica's current location. PLaces apart across the globe contain coal deposits of similar age that were formed in tropical conditions; they are no longer in tropical climatic belts therefore must have drifted apart since the Carboniferous period.

New Evidence:
- Discovery of the Mid-Atlantic Ridge (1948)
- Paleomagnetism and the reversal of the Earths magnetic field (1950s)
- Seafloor spreading and then carbon dating of the seafloor rocks (1960s)

After passing the Curie Point, iron ions within the lava will
align to magnetic north......

.....This means that as the seafloor has spread, and magnetic reversal has occured in
the past, stripes are visible on the seafloor, preserving a record of the Earth's polarity at the time
of the lava cooling. This has helped to support the idea of seafloor spreading as the youngest
 rock is located nearest to the ridge.

Hopefully, this timeline summarises the key dates and discoveries we need to know about!


Structure of the Earth:

1. Crust :- it is the upper layer which is solid and is divided into 2 types;
       - Oceanic crust = mainly basaltic in nature and around 6-10km thick. It is more dense and younger than continental curst
       - Continental crust = composed of a wide variety of igneous, metamorphic and sedimentary rock. Can be as much as 70km thick.

2. Moho Discontinuity :- boundary between the crust and the mantle. Average depth of 8km below oceanic crust and 32 km below continental crust. Has density similar tp an olivine-rich rock such as peridotite and so is less dense than the mantle; as such seismic waves accelerate in this region.

3. Mantle :- below the crust. Upper part is solid and is part of the lithosphere. Below this is the asthenosphere which is partly molten and can flow, whilst the rest of the mantle is liquid.
       - Lithosphere = consists of the outer solid part of the Earth, which includse the crust and rigid upper mantle. The lithosphere is about 100km thick, although thickness is age dependent (oldest=thickest). Lithosphere below the crust is brittle enough at some locations to produce earthquakes by faulting, such as within subducted oceanic plate.
      - Asthenosphere = ductile part of the Earth just below the lithosphere, including the lower mantle. It is about 180mk thick. Relatively slow seismic movements compared to the lithosphere.

4. Gutenburg Discontinuity :- boundary between the outer core and the mantle. Where thermal nuclear reactions occur that start convection cells off in the mantle, sending plutons of hot magma upwards. Located at a depth of about 2,800km and marks a sudden increase in density.

5. Outer Core :- liquid iron-nickel alloy, temperatures of over 6000C.

6. Inner Core : - Solid iron-nickel alloy. Even though temperature is higher than the outer core, the pressure produced by overlying weight is strong enough to prevent the liquid state.

How do we know this? Well, studies of earthquake waves, with regards to the velocities and paths of such waves,  depends on what excatly it is they are passing through. P waves can travel through anything but S waves can only pass through solids; so by studying these waves it has been possible for scientists to determine the physical composition of the Earth's interior.

Convection Currents = Driving Force

- Occur in the mantle, very slow convection currents flow in the asthenosphere
- Provide horizontal forces on the plates of the lithosphere, with high temperatures causing updoming and tensional forces pulling the crust apart
- Start in the Gutenburg Discontinuity where thermal nuclear reactions send a pluton upwards

Boundary Types

The Earth's lithosphere is split up into 7 major plates, and around 14 minor ones, with some plates composed of both oceanic and continental crust. Between these plates are boundaries/margins, and there are three main types.......
----- I am going to do a seperate post for each boundary type but, in short:-

- Divergent (constructive) = Plates move away from each other, generating tensional forces. Consequently, characterised by shallow-focus earthquakes and volcanoes producing basaltic magma, forming new oceanic crust. Produces oceanic ridges and rift valleys.

- Convergent (destructive) = Plates move towards one another, generating compressional environments, therefore are characterised by deformation, volcanism, mountain building, seismicity and mineral deposits. Three possible types:-
                                                                - Oceanic vs Oceanic
                                                                - Oceanic vs Continental
                                                                - Continental vs Continental

- Conservative = Plates move laterally past each other, or in the same direction at different speeds. Produces a lot of shear stress as lithosphere is neither destroyed or created. No volcanic activity but lots of shallow-focus earthquakes, intensely shattered rock and characterised by production of faults parallel to plate movement.

The Revenge of Gaia - A student's book review

I really need to get into the habitat of reading a book and then writing the book review, not waiting a few months before I do so - however, seeing as I read this book in the summer holidays, it will be a good test of how much I can remember!

This book is another one of James Lovelock's and you really need to have read the first one, if you are to make any sense of this book. The first book 'Gaia' explains the idea of the Gaia theory and how it was created. So, just for a quick reminder, the Gaia theory, in its simplest form, suggests that the physical and chemical conditions of the surface of the Earth, of the atmosphere, and of the oceans has been and is actively made fit and comfortable by the presence of life itself; whilst also encompassing the belief that life does not regulate or make the Earth comfortable for itself. Instead, regulation, at a state fit for life, is a property of the whole evolving system of life, air, ocean, and rocks and with a mathematical basis in the model Daisyworld which generates testable predictions. Basically, the Earth is kind of alive as one big organism and self-regulates - I will warn you again, read these books with quite an open mind and when you have the time to really think about and process the ideas the author is trying to present; it was a totally new, but intriguing, idea for me and I think I am still trying to totally get me head around it! Perhaps its no suprise that when this theory was first published it was viewed with great suspiscion and skepitism, but it seems to be becoming  more widely accepted within the scientific community.

This time, instead of presenting and trying to prove the Gaia hypothesis, Lovelock applies it to global climate change, although he seems to prefer the use of global heating, which he thinks to some extent is unavoidable as a consequence of current levels of anthropogenic forcing and will abruptly occur. Throughout the book it is incredibly clear that he feels anthropogenic forcing is solely responsible for current and impending climatic alterations and that our actions have and prevail to destabilise the Earth and, as the title implies, in revenege Earth is readjusting and consequently generating less habitable conditions for us. Lovelock is definetly not afraid of presenting his ideas and views (for example, he clearly states his view that global climate change is irreversible, something which was not necessarily recieved so well by those trying to persuade people to lead more 'green' lifestyles!) in an attempt to alter the way we think and whilst I find it hard to accept everything he says, it is, again, an incredibly thought provoking book.

There are a couple ideas/views that Lovelock mentioned which have really stuck in my mind. As also touched upon in his first book, within The Revenge of Gaia he clearly emphasises his support for nuclear power, viewing it as an efficient and less environmentally damaging energy resource than those currently exploited (i.e oil and coal!). Nuclear power is always going to be a controversial issue, perhaps more so after events in Japan earlier this year, and so I wonder if Lovelock's view of nuclear power has changed in anyway since he wrote this book. It is a resource that could be exploited, but like all sources of energy it has its disadvantages and risks which cannot be ignored and also, it cannot solve the issue of removing the global dependency on oil. Many of his ideas almost seem to go against the more conventional way of thinking, i.e we should use appropriate technology (normally very low-tech) to enable sustainable development so that society can not only reduce anthropogenic forcing and sustain existance but also adapt to coming changes. Lovelock seems to feel that we need a more high-tech approach but not in an attempt to solve the coming 'climate crisis', as he feels we have already lost the oppurtunity to implement sustainable development, instead to enable mankind to perform a sustainable retreat from our current level of control and detrimental influence we have over Earth. This high-tech approach is the only way he feels that we can feed the world's population which is probably true. I fail to see how organic farming can remain an efficient and viable option in the future and with issues with energy supplies and future climatic alterations, traditional agricultural practices are going to become increasingly challenging to entertain. Feeding the global population is a common worry shared by many, including Lovelock, who suggested that Britain could be one of a very few countries (so long as we implemented tight rules on immigration) who could revert back to being self-sufficient and sustain its population in the future without import reliance. However, Lovelock's suggestion of who we could achieve this is interesting to say the least.............. he suggested that we took Scotland, England and Wales and reserved one for living space, one for food and left the remainder of the Britain as a Gaia friendly region. If this was every suggested in parliament I would be intrigued to see how they would decided which areas to have as which of these three key regions - could be an interested discussion! Would it work? Well, I cannot see any such decision being recieved well enough for such a scheme to work unless it was absolutely necessary so lets just hope it doesn't come to this! So what does he feel is the root cause of this environmental problem? Well, you can probably guess and most of you will agree - population growth. He thinks its quite simple, there are too many of us who live unsustainable lifestyles. If there was only about 1 billion of us on the planet then we could probably live whatever way we wanted to and have no lasting impact but there are 7 billion of us and so we simply cannot. Again, his answer is a 'sustainable retreat' from the detrimental control and influence we excercise over Gaia and if we fail to do so he warns we will experience "a global decline into a chaotic world ruled by brutal warlords on a devastated Earth" and practically on this note the book ends; unfortunately the idea of a 'chaotic world ruled by brutal warlords on a devasted Earth' could become a reality in the future as, currently we are prepared to fight over unessential resources i.e oil, so what will we be prepared to dp when we are fighting over items needed for survival, principally water and food? If you ask me, that is a slightly worrying thought and I don't feel very optimistic about the answer.......

Like my conclusion for the review of Gaia, its really hard to know what to say about this book but if you have the time, I would try and read it. For many of you, as with me, it will be a totally new way of thinking and perspective on life, consequently making it a very thought provoking book. I do wonder how Lovelock comes up with such ideas. I cannot deny that it does intrigue me and is a very different way of thinking, consequently I feel there is only so much my brain can cope with reading about it at one time. I quite like the way he links feedbacks together to try and prove his point but I think perhaps some of it has been slightly over thought and, perhaps because I am personally better at dealing with the tangible, I kind of feel like there is an element of reluctancy to test his theory - although I am not 100% sure how you could test this hypothesis! You cannot deny that many things are interlinked but the idea that Earth is sort of like an omniscient, omnipotent superorganism that self-regulates in an almost indentical way to the bodies process of homeostatis, and then in an act of revenge against anthropogenic activity, readjusts to make life difficult for humanity, is a leap am I struggling to make and accept in my mind.

Anyway, if you get around to reading it, let me know what you think! The ideas are hard to process and I found the easiest way to do so was to discuss it......

All those 'lovely' development acronyms............

Okay, so I realise that my blogging record since we started back in September has been appalling but I am going to try and sort that out so that I start writing regular and (hopefully!) useful blog posts again. My plan for the next few weeks is to write all the book reviews of the books I have been reading over the last half term, write a couple posts on current issues/discursive topics relevant to the Development and Globalisation module we have just finished, write a summary sort of revision post on everything we have covered so far (with special emphasise on the areas that people have asked me to write posts on) and then make a start on our exciting new module - Plate Tectonics and Associated Hazards! So where to start? Well, after my classes appalling performance in the quiz on Monday, I thought a post on all the development acronyms was desperately required. There are quite a few to remember so let me know if I miss any off this list!

Classification of Countries
LDC = Less Developed Country
e.g Sierra Leone, Haiti, Myanmar
- 33 out of the 50 LDC's are sub-Saharan
- highest HDI ranking of LDC is Gabon at 119th and then South Africa at 121st (out of 197)
What makes an LDC?
1. Income below $750 per capita per year
2. Weak human resources
     - Health
     - Education
     - Nutrition and calorie uptake
3. Economic vulnerability
     - Instability of exports
     - Instability of agricultural production

MDC = More Developed Country
e.g USA, UK, Norway

NIC = Newly Industralised Country (more than last 40 years)
e.g South Korea, Hong Kong

RIC = Recently Industralised Country (last 40 years)
e.g Brazil, Russia

ORC = Oil-Rich Countries
e.g Qatar, Saudi Arabia

LLDC = Land-Locked Less Developed Country
e.g Central African Republic, Bhutan, Moldova, Bolivia
SIDS = Small Island Developing States
e.g Vanuata, Dominican Republic, Seychelles
HIPC = Heavily Indebted Poor Countries
e.g Rwanda, Ghana, Afghanistan
- 29 out of the 40 HIPC's in the world are sub-Saharan

Development Indicators
HDI = Human Development Index
= Compoisite indicator first used by the UN in 1990 to replace the sole use of GDP
Takes into account:-
   - GNI PPP per capita
   - Years of schooling
   - Life expectancy at birth
End figure is between 0 and 1, with proximity to 1 indicating development of a country
e.g 1st = Norway 0.943, 28th = UK 0.863, 84th = Brazil 0.718, 101st = China 0.687, 134th = India 0.547, 187th = DR Congo 0.286 - it is worth checking out an updated list as this years results were released by the UN last week

HPI = Happy Planet Index
- Introduced by the New Economics Foundation (NEF) in 2006
- Doesn't indicate which is the happiest country in the world but the relative ecological efficiency with which human well-being is delivered around the world
- First index to combine environmental efficiency with human well-being
- However it is based mainly on opinions not facts and so is subjective
e.g 1st = Costa Rica, 2nd = Dominican Republic, 3rd = Jamaica, 20th = China, 74th = UK

PQLI = Physical Quality of Life Index
- Developed in the 1970s due to dissatisifaction with the use of GDP
Takes into account:-
   - Literacy Rates
   - Infant Mortality
   - Life expectancy at age 1
- Criticised as there is considerable overlap between IMR and LE

GDP = Gross Domestic Product
= the total calue of goods and services within a country (including foreign companies)
What are the issues with using GDp per capita as a measure of development?
1. Inequalities: - In many LDCs the wealth remains with a few people with control over the government and industry so does not filter down through the population
2. Informal Employment : - In LDCs many people work in the informal business sector, such as street vending, and so money is exchanged without record and, therefore, does not appear during GDP calculations
3. Subsistence Lifestyles: - Many farmers lead a subsistence lifestyle and so it is impossible to accurately measure income and population

GNP = Gross National Product
= the total value of goods and services for a country's companies at home and abroad

GNI = Gross National Income
= GDP plus or minus the interest and repayments on debt

PPP = Purchasing Power Parity
= essentially a measure of the value of the local currency (basically how much can be brought in a country with a set amount of money)

International Groupings
EU = European Union
- 1957 Treaty of Rome created the European Economic Community (EEC) which had 6 members (France, Italy, West Germany, Belgium, Netherlands and Luxemburg). Slowly more and more countries have joined and there are now 27

AU = African Union
- Founded in 2002 to succeed the Organisation of African Unity (OAU)
- Includes all African nations apart from Morocco who left the OAU in 1984 and Madagascar who were suspended in 2009
Aims to: -
   - Accelerate political and socio-economic integration of the continet
   - Promote democracy and human rights
   - Achieve continental peace
   - Promote and defend Africa's voice in world affairs

NAFTA = North American Free Trade Agreement
- Founded in 1994 to create a free trade zone, encourage investment in each other and promote competition
- Grouping consists of USA, Canada and Mexico

NATO = North Atlantic Treaty Organisation
- Founded in 1949, with 28 members, and is classed as an intergovernmental military alliance
- Accounts for 70% of the world's defence spending

OPEC = Organisation of Petroleum Exporting Countries
- Founded in 1961 and consists of 12 countries all of which are net exporters of oil. They are responsible for setting the global oil prices

OECD = Organisation of Economic Cooperation and Development
- Founded in 1961 to replace the Organisation of European Economic Cooperation (OEEC) which was founded in 1948
- Includes 34 countries and aims to stimulate economic progress and world trade

AOSIS = Alliance of Small Islands States
- Established in 1990 with 42 countries to consolidate the voices of SIDS to address global climate change

UN = United Nations
- Founded in 1945 and has 193 members
- Aims to promote and provide international law and security, economic development, social progression, human rights and world peace

APEC = Asia-Pacific Economic Cooperation
- 21 members bordering the Pacific Ocean all pledging free trade

G-8 = Group of 8
- Group of the worlds major economies. Founded in 1975 with France, Canada, Germany, Italy, Japan, UK and USA. Russia was then added to make it the G-8 in 1997.

G-20 = Group of 20
- The G20 was established in 1999, in the wake of the 1997 Asian Financial Crisis, to bring together major advanced and emerging economies to stabilize the global financial market.


G-77 = Group of 77
- Currently 130 members who are all LDCs, constituting the largest intergovernmental organisation of developing states in the UN, providing LDCs with a greater voice. China has always been an very close ally of this group but is not an offical member.

BRIC = Brazil, Russia, India, China / BRICM = BRIC + Mexico
- The world's emerging markets
- Why do the BRIC's matter?

All the others which I can't think of a catergory for

MDG = Millenium Development Goal

- Eight development goals that 23 internation organisations and all 193 UN members agreed to aim to achieve by 2015

TNC = Transnational Coporations  MNC = Multinational Coporations
- Corporation that has production establishments or delivers services in at least two countries. Some TNCs have grown so large that they have budgets that exceed those of many countries in which they operate

FDI = Foreign Direct Investment

CPC = Communist Party of China

SEZ = Special Economic Zone
e.g Many set up in China, for example, like Bejing to act as growth poles and all development to spread

SAR = Special Adminstrive Regions
e.g Hong Kong

GATT = General Agreement on Tariffs and Trade
- Formed in 1947 during the UN Conference on Trade and Employment but only lasted until 1994 when it was replaced by WTO

WTO = World Trade Organisation
- Replaced GATT and aims to gradually lower barriers to international trade. Liberalising organisation created by capitalist economies

IMF = International Monetary Fund
- Founded in 1945 with 29 members but has since grown to 187
- Promotes international economic cooperation

DfID = Department for International Development
- UK government department that seperated from the Foreign and Commonwealth Office in 1997
- Aims to promote sustainable development and eridicate world poverty

NEF = New Economics Foundation

UNESCO = United Nations Education, Scientific and Cultural Organisation

ERDF = European Regional Development Fund
- Aims to strengthen economic and social cohesion in the EU by correcting imbalances between its regions

ISO = International Organisation for Standardization
- Ensures the standardization of containerization across the globe

NGO = Non-Governmental Organisation

I don't think I really appreciated just how many there were until I started writing them down! Hope this helps - let me know if I missed any of the list....