Is the youngest part of a rock from the bottom up or from the top to the bottom?

How do scientists tell how old a rock is other than that?

What is true of all organisms in the kingdoms protista, plantae, fungi, and animalia? a. they are multi-celled. b. they are photosynthetic. c. they have cells that contain membrane-bound organelles. d. they contain cells that lack membrane-bound organelles.

Eutrophication caused by human nutrient pollution.

What are 3 reasons that natural selection occurs