Most notable is William Thomson, ennobled to become Lord Kelvin in 1892, whose theories make up an entire section of this collection.

What rocks are used for radiometric dating video

Older periods which predate the reliable fossil record are defined by absolute age.

Each era on the scale is separated by a major and/or changing event.**If the images and/or text on any of the web pages do not appear evenly spaced and centered on your screen, which commonly occurs with AOL pages, maximize the individual page's window.

He inferred that where the layers are not horizontal, they must have been tilted since their deposition and noted that different strata contain different kinds of fossil.

Robert Hooke, not long after, suggested that the fossil record would form the basis for a chronology that would “far antedate ...

It is a drama consisting of a prologue and three acts, complex characters, and no clear heroes or villains.

We, of course, know the final outcome, but we should not let that influence our appreciation of the story as it unfolds.The third act sees the entry of a newly discovered set of physical laws—those governing radioactivity.Radioactivity offered not only a resolution to the puzzle of the earth’s energy supply but also a chronology independent of questionable geologic assumptions and a depth of time more than adequate for the processes of evolution.This position came to be known as uniformitarianism, but within it we must distinguish between uniformity of natural law (which nearly all of us would accept) and the increasingly questionable assumptions of uniformity of process, uniformity of rate and uniformity of outcome.That is the background to the intellectual drama being played out in this series of papers. Roman poet Lucretius, intellectual heir to the Greek atomists, believed its formation must have been relatively recent, given that there were no records going back beyond the Trojan War.