Geology

The book I read to research this post was Geology For Dummies by Alecia M Spooner which is an excellent book which I bought from kindle. I learned quite a lot from this book which might be surprising because some years ago I did the first year of an A level course. It tells you all about the history of the Earth how it was formed and also the different phases of life and how this is ongoing. Oceanic crust which is the rock layer that separates the oceans from the next layer the magma, is only 5 miles thick. Continental crust and also the mountainous form is much thicker at upto 43.5 miles for the latter type. At one time there was one supercontinent initially called Rodentia which was then added to and eventually became Pangeae. This then split in 2 and the north part became Laurentasia & the southern part became Gondwona. Gradually this fragmented and interestingly at one stage India was a separate landmass. Of course as India collided with Asia the Hymalayas were formed. The study of these plates of rock that float on magma and move about causing volcanoes and earthquakes is called Plate Tectonics. Earthquakes are measured on the Richter scale named after Charles Richter who devised it and each time a whole number is increased it means the earthquake is increased by a factor of 10. Hence a category 2 earthquake is 10 times greater than a category 3 one and a hundred times greater than a category 4 one. In the Ice Ages there were many large mammals even including giant marsupials and the reason was they are more efficient at staying warm much like the polar bears we have in the arctic nowadays.