Ask yourself how the things that are happening in the world today might end up being recorded in the sediments that are now or soon will be deposited.
How would today's sediments appear to a geologist millions of years in the future examining outcrops of sedimentary rock that originated in our time?
For instance, an orogenic episode (a long geologic episode of mountain building) may finally come to end and the eroded mountains may be buried beneath a new sequence of sediments.
They are summarized as the Principles of Relative Geologic Age Determination, sometimes referred to as the Principles of Relative Dating.
The absolute dating methods proved that the relative dating methods had been correct, and now geologists can say not only state the sequence of geologic time, they can also estimate fairly accurately how many years ago each division in the sequence occurred.
Another essential concept in stratigraphy is the unconformity.
There are several specific types of unconformities.
The three major, specific types of unconformities are included here.