John Hawks is in the middle of explaining his research on human evolution when he drops a bombshell. He rattles off some dismaying numbers: Over the past 20, years, the average volume of the human male brain has decreased from 1, cubic centimeters to 1, cc, losing a chunk the size of a tennis ball. The female brain has shrunk by about the same proportion. Possibly owing to said shrinkage, it takes me a while to catch on.

How old are rocks?



Dating Rocks and Fossils Using Geologic Methods | Learn Science at Scitable
As a member, you'll also get unlimited access to over 79, lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Already registered? Log in here for access. Log in or sign up to add this lesson to a Custom Course. Log in or Sign up. In previous lessons, we talked about the Geologic Time Scale and how scientists use it to piece together the history of the earth.


Absolute dating
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Flood geology also creation geology or diluvial geology is the attempt to interpret and reconcile geological features of the Earth in accordance with a literal belief in the global flood described in Genesis 6—8. In the early 19th century, diluvial geologists hypothesized that specific surface features were evidence of a worldwide flood which had followed earlier geological eras ; after further investigation they agreed that these features resulted from local floods or glaciers. In the 20th century, young Earth creationists revived flood geology as an overarching concept in their opposition to evolution , assuming a recent six-day Creation and cataclysmic geological changes during the Biblical Deluge, and incorporating creationist explanations of the sequence of rock strata. In the early stages of development of the science of geology , fossils were interpreted as evidence of past flooding. The "theories of the Earth" of the 17th century proposed mechanisms based on natural laws, within a timescale set by the biblical chronology.