Scientists establish the age of a rock or fossil based on natural radioactive decay and certain elements such as potassium and carbon, this is used to make reliable “clocks” to date ancient events.
(Sorry if not all is accurate hope it helps)
Answer:
rise over run
Explanation:
rise refers to the number of units going u or down a graph
run refers to the number of units going left or right
it is seen as so; 
, 
, or 
Don't panic when I included "delta". Delta, it refers/means the small mathematical triangle found beside the rise and run symbols of y and x
Answer: Snails have soft bodies and are protected by shells, which are the characteristics of gastropods mollusks.
Shear causes horizontal movement along a fault plane in a strike-slip fault.
After the Cretaceous–Paleogene extinction event wiped out the non-avian dinosaurs (birds being the only surviving dinosaurs) and several mammalian groups, placental and marsupial mammals diversified into many new forms and ecological niches throughout the Paleogene and Neogene, by the end of which all modern orders had appeared.
