After the uplift of the land, the forces of erosion attacked the highlands and the eroded rock debris was transported and redeposited in the lowlands.During the same interval of time in another part of the world, the land surface subsided and was covered by the seas.Christopher was there at the beginning of my single days — living with Simone and me in the big blue house, his friendly Bernese Mountain Dog a constant cuddly presence in our lives.
From the results of studies on the origins of the various kinds of rocks (petrology), coupled with studies of rock layering (stratigraphy) and the fossils they contain (paleontology), geologists have associated layers of rocks with sequence of events thought to have occurred over hundreds of millions of years.
For example, it is believed that during a particular episode the land surface was raised in one part of the world to form high plateaus and mountain ranges.
Between the years of 17, James Hutton and William Smith advanced the concept of relative dating.
Hutton, a Scottish geologist, first proposed formally the fundamental principle used to classify rocks according to their relative ages.
Geologists have divided the Earth's history into Eras -- broad spans based on the general character of life that existed during these times -- and Periods -- shorter spans based partly on evidence of major disturbances of the Earth's crust.