Bertram boltwood radiometric dating

Simply put, Smith proposed that the lowest rocks in a cliff or quarry are the oldest, while the highest are the youngest.By observing fossils and rock type in the various layers, it was possible to correlate the rocks at one location with those at other locations.Smiths work, combined with the first discoveries of dinosaur fossils in the early 1800s, led to a framework that scientists still use today to divide Earths long history into the geologic time scale, with its various, arbitrary divisions of time including eras, periods, and epochs.

The names of the stages or ages most often depend on city and regions where the rocks were found; this is why division names frequently vary on geologic time scale charts from different countries.The following table is a general listing of the geologic time table based on current interpretations of rocks and fossils.The Geologic Time Scale (in millions of years ago) Most of the major divisions on the geologic time scale are based on Latin names, or areas in which the rocks were first found.His father, a lawyer, died when "Bolty" was two years old, and the boy, an only child, was raised by his mother in her home town of Castleton-on-Hudson, New York.His mother's family had come to America from Holland, also in the 17th century.

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