With the sinking of the land surface, sediments were deposited on the ocean floor.Such recurring events as mountain building and sea encroachment and believed to be recorded in rock layers that comprise units of geologic time.The concept is considered by uniformitarian geologists to be a major breakthrough in scientific reasoning by establishing a rational basis for relative time measurements.
By using dendrochronology scientists have dated certain living trees to having ages of around 4600 years.
we often make reference to fossils to explain the past of living beings. Fossils are remnants (complete or partial) of living beings that have lived in the past (thousands, millions of years) or traces of their activity that are preserved generally in sedimentary rocks.
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.
The "relative" positions of layers and fossils to assign estimated dates to strata.
Dendrochronology is a technique of dating past climatic changes through a study of tree ring growth.
Each year a tree adds a layer of wood to its trunk and branches thus creating the annual rings we see when viewing a cross section.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. Have you ever wondered how science knows the age of a fossil? If you think of a fossil, surely the first thing that comes to your mind is a dinosaur bone or a petrified shell that you found in the forest, but a fossil is much more.So, there are different types of fossils: Obviously fossils became more common after the appearance of hard parts (shells, teeth, bones …), 543 million years ago (Cambrian Explosion).He concluded, after studying rocks at many outcrops, that each layer represented a specific interval of geologic time.