https://padlet.com/megan96/i7pf0i03g2pp By: Megan Mieure en-us 2018-07-07 14:13:30 UTC 2018-07-07 14:19:40 UTC hello@padlet.com megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617380 2018-07-07 14:14:46 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617380 megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617395 In 1862 Lord Kelvin tried to find how long it would take for the earth to cool and become solid and it was 20 to 400 million years ago. Current scientists don’t believe that he was correct but they found that his work was scientifically based. 

]]> 2018-07-07 14:15:26 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617395 megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617422 Scientists tried to use the layers of rocks to date the earth accurately. The process of reading the rock layers was hard but they eventually found that the earth was billions of years old.

]]> 2018-07-07 14:16:09 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617422 megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617457 Around the 1940’s and 1950’s Radiometric dating was developed and used to help date the earth. They found that heavy elements can decay into lighter ones. They compare the radioactive element and how it decays and they find the half life of the material. The method was used in the earth’s crust to find the half life of the rocks there and found that the earth was at least 3.8 billion years old

]]> 2018-07-07 14:17:01 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617457 megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617480 2018-07-07 14:17:46 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617480 megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617503 By using a combination of these methods we have found that the earth is 4.5 to 4.6 billion years old.]]> 2018-07-07 14:18:40 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617503 megan96 https://padlet.com/megan96/i7pf0i03g2pp/wish/269617528 http://earthsky.org/earth/how-old-is-the-earth ]]> 2018-07-07 14:19:17 UTC https://padlet.com/megan96/i7pf0i03g2pp/wish/269617528