Scientists collected evidence from to determine when rocks were laid down in layers, and they compared rocks and index fossils worldwide to organize the scale.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

ya the other dude is right

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added