Layers of rock are deposited horizontally at the bottom of a lake (principle of original horizontality).
Younger layers are deposited on top of older layers (principle of superposition).
A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved.
" First, the relative age of a fossil can be determined.
Relative dating puts geologic events in chronological order without requiring that a specific numerical age be assigned to each event.
Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years.
Mountains have been built and eroded, continents and oceans have moved great distances, and the Earth has fluctuated from being extremely cold and almost completely covered with ice to being very warm and ice-free.
Layers that cut across other layers are younger than the layers they cut through (principle of cross-cutting relationships).