These methods — some of which are still used today — provide only an approximate spot within a previously established sequence: Think of it as ordering rather than dating.
Biostratigraphy: One of the first and most basic scientific dating methods is also one of the easiest to understand.
The successive layers of rock represent successive intervals of time.
Since certain species of animals existed on Earth at specific times in history, the fossils or remains of such animals embedded within those successive layers of rock also help scientists determine the age of the layers.
Some may argue that in today's society, it is nonexistent and has been replaced by what many young people refer to as "hooking up." With the advent of new technologies (e.g., cell phones, instant messaging, video chatting, etc.) and the changing definitions of traditional dating and families, "dating" has become a more open and self-interpreted institution over the century.
Before the advent of absolute dating methods in the twentieth century, nearly all dating was relative.
The main relative dating method is stratigraphy (pronounced stra-TI-gra-fee), which is the study of layers of rocks or the objects embedded within those layers.
This method is based on the assumption (which nearly always holds true) that deeper layers of rock were deposited earlier in Earth's history, and thus are older than more shallow layers.
Similarly, pollen grains released by seed-bearing plants became fossilized in rock layers.
The world of dating in America has changed dramatically over the last century.