How did scientists determine earths layers?

Drag and drop a statement or reason to each box to complete the proof. statement reason △abc , de⎯⎯⎯⎯⎯∥ac⎯⎯⎯⎯⎯ given corresponding angles postulate △bde∼△bac babd=bcbe polygon similarity postulate ba=bd+dabc=be+ec bd+dabd=be+ecbe substitution property of equality bdbd+dabd=bebe+ecbe addition of fractions 1+dabd=1+ecbe simplify. dabd=ecbe subtraction property of equality

17. the soil erosion pictured here is the result of what? a. harvesting renewable resources at a rate greater than the sustainable yield b. a mudslide caused by excessive rains c. harvesting renewable resources at a rate lower than the sustainable yield d. the transition between geologic eras and eons

How has the geography of india made it difficult for its people to expand before modern technology?