Which phrases are true of only the mantle? made of three layers
has a tarry layer
made of two layers
has a molten outer layer
has a solid outer layer

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating

Which of the following may one conclude from a map that shows the average ph value of rainfall in the u. s.? acid rain is a more serious problem on the east coast. acid rain falls equivalently across the continental u. s. there are more factories on the west coast. the midwest has fewer forests than the rest of the u. s.

The part of the eye that closes and opens to let light in is .