What is the main purpose of the geologic time scale?

Its in the national history museum and you can't se the original because its locked away in a vault 

Answer// dinosaurs emerged during mesozoic era;

The us is first  the  u.s. economy  remains the  largest in the world  in terms of nominal  gdp. however, the  u.s. economy  loses its spot as the number one  economy  to china when  measured  in terms of  gdp  based on ppp. in these terms, china's  gdp  is $23.19 trillion exceeds the  u.s. gdp  of $19.42 trillion

The bottom part thats where most farming goes on