National Old Rock Day

National Old Rock Day

 

January 7, 2015 is Old Rock Day!

Did you know?  By dating the zircons embedded within the Acasta gneiss (the rock above-which happens to be the oldest known rock), geologists have determined its age to be 3.96 billion years. This rock’s composition establishes it as part of a continent, indicating that continents existed nearly four billion years ago.

Source: www.amnh.org

 

Did you know?
Most of the ocean floor is made of basalt. This igneous rock continues to flow out of Earth from chains of underwater volcanoes known as “mid-ocean ridges.

Source: www.factmonster.com