Please HELP! 3 Earth Science questions!?

[sapphire]

Please write your answers in full sentences, thanks.

47. Explain some of the factors that make it difficult for geologists to learn about the Precambrian era.

48. Earth can be divided into three zones based on differences in incoming solar radiation. Identify these zones. Describe their location and general climate. Also, discuss how the sun’s energy strikes each zone.

50. Describe the substances that make up the planets and their atmospheres.

 

[oklatonola]

This one has been reported as well. Thanks so much for two more points.

 

[Pete Mcgeape]

47: because No animal were present in that era to be fossilized and for us to study, And that rock is the foundation of the earth's crust it would be a enormous task to get to that rock
48:Im not sure but i think the Tropic of Capricorn,Tropic of Cancer , and the other one, The amount of the solar radiation affect the heat and radioactive rays thus causing more cancer.
50: i think it's hydrogen not sure thought