What main criterion determines major divisions in the geologic time scale?(1 point)

shifts in the position of Earth in its orbit

different stages in human evolution

the occurrence of huge events in Earth's natural history

times of major climate change

one state would change   like louisiana to texas. thats a change

explanation:

answerspecific gravity;

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.