What would the geologist be able to deduce about the world we live in, based on what was left in the strata?
Stratigraphy started to become a formal science due to the work of a man who published under the name Nicolaus Steno in the 17th century.
The combination of these two types of geologic ages makes a complete record of earth's geologic history in terms of the order of events and in terms of how many years ago each event occurred.
Steno recognized that fossils represent organisms that became buried in sediment, which later turned into rock.
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?
Geologists still use Steno's principles, with some refinements and additions.
They are summarized as the Principles of Relative Geologic Age Determination, sometimes referred to as the Principles of Relative Dating.