The Earth's Ages

The Earth is where we live. The Earth is old. Currently believed to be around 4,570 million years old, give or take a year. Please note that this is considerably longer than the 6 thousand years that certain mythologies propose. Why these mythologies are still believed is another matter entirely. It should also be noted that the Earth is relatively young with the origin of the Universe hanging somewhere around 13.7 billion years ago.

So how is the age of the Earth documented? We all know (or think we know) about the Jurassic (Park) and the Cretaceous, but can you put them in order? Do you know which Age or Eon we are in now? Good, because I do now too.

The largest defined unit of time is the Eon. Eons are divided into Eras, which are in turn divided into Periods, Epochs and Stages. Now, some history on the Earth's history:

The first serious attempts to formulate a geological time scale that could be applied anywhere on Earth took place in the late 18th century. The most influential of those early attempts (championed by Abraham Werner, among others) divided the rocks of the Earth's crust into four types: Primary, Secondary, Tertiary, and Quaternary. Each type of rock, according to the theory, formed during a specific period in Earth history. It was thus possible to speak of a "Tertiary Period" as well as of "Tertiary Rocks." Indeed, "Tertiary" and "Quaternary" remained in use as names of geological periods well into the 20th century.

The identification of strata by the fossils they contained, pioneered by William Smith, Georges Cuvier, Jean d'Omalius d'Halloy and Alexandre Brogniart in the early 19th century, enabled geologists to divide Earth history more precisely. It also enabled them to correlate strata across national (or even continental) boundaries. If two strata (however distant in space or different in composition) contained the same fossils, chances were good that they had been laid down at the same time. Detailed studies of the strata and fossils of Europe produced, between 1820 and 1850, the sequence of geological periods still used today.

Study the following information: Wikipedia: Geologic Time and Smithsonian: Geologic Time so you can be smart, and because thirst for it, and tell all your friends how old you really are, because the DNA in your cells goes back to the origins of life on this planet, some 400 million years, and the atoms that make up those cells go back to the origins of the universe and time. We are all very old indeed.

Also: Remote Sensing: Geologic Time