The 366 daily episodes in 2014 were chronological snapshots of earth history, beginning with the Precambrian in January and on to the Cenozoic in December. You can find them all in the index in the right sidebar. In 2015, the daily episodes for each month were assembled into monthly packages, and a few new episodes were posted. Now, the blog/podcast is on a weekly schedule with diverse topics, and the Facebook Page showcases photos on Mineral Monday and Fossil Friday. Thanks for your interest!

Sunday, January 12, 2014

January 2: 4,300,000,000 years ago



by Richard I. Gibson

The basic structure of the earth had formed by about 300,000,000 years after it began. This involved the further separation of denser and lighter materials, as well as things like water and gases being emitted to form the oceans and atmosphere.


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Image by Kelvinsong, via Wikipedia, under Creative Commons license

4 comments:

  1. The earths crust is as thin as 3 miles? Where?

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    1. Oceanic crust is typically 3-5 miles thick under the oceans. Continental crust is much thicker, around 25 miles, but thinner in places and significantly thicker under mountain ranges. http://volcano.oregonstate.edu/education/vwlessons/lessons/Earths_layers/Earths_layers4.html

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  2. Was there already a solid core 300 million years after the Earth's formation, or was the core all liquid? And today, 4 billion years later, is the solid core slowly growing at the expense of the liquid core, or is its size static? A more comprehensive question could be this: which of these two is larger, heat generation by radioactive decay or heat loss by convection to the surface? In other words, is the interior of the Earth slowly cooling down or slowly heating up?

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    1. Excellent question. I'll add it to the list of future episodes because I think it will take some research - which is to say, the answer isn't simple. Thanks!

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