G. Brent Dalrymple is a geologist at Oregon State University (now retired). He received the National Science Medal in 2005. This is the USA's highest award for scientific achievement. Dalrymple has published two books on the age of the Earth: The Age of the Earth (1991), and Ancient Earth, Ancient Skies: The Age of Earth and Its Cosmic Surroundings (2004). The first book grew out of his preparation for the 1981 creationist trial in Arkansas that resulted in overthrowing the "equal time" law. Michael Ruse writes of his testimony at that trial [in Science and Creationism, see NCSE Supporter Dalrymple receives National Medal of Science]
Rounding out the science witnesses was G. Brent Dalrymple of the U.S. Geological Survey. He gave a quite brilliant disquisition on methods of dating the earth. One would not think that such a topic could be all that intrinsically interesting, but Dalrymple gave this assumption the total lie. He held us absolutely spellbound as he talked of various dating techniques and how geologists compensate for weaknesses in one direction by strengths from another. My sense was that Dalrymple was so good and so firm that he rather broke the back of the State's case. He had checked all of the Creationist arguments and showed in devastating detail the trail of misquotations, computational errors, out-of-date references, and sheer blind stupidity which allows the Creationists to assign the earth an age of 6000 years. After Dalrymple, the State seemed far less ready to tangle with witnesses.The following except is from The Age of the Earth. It can only give a bit of the flavor of Dalrymple's writing. In my opinion this book is one of the classic science books of the 2oth century. Richard Dawkins did not include G. Brent Dalrymple in The Oxford Book of Modern Science Writing.
Four and one-half billion years. That figure, which represents the current estimate of the age of the Earth, is so large, so far outside of our normal everyday experience that it is difficult to comprehend its true scope and meaning. Even scientists who deal with numbers of that magnitude on a daily basis often find it difficult to grasp the full significance of that span of time. If a piece of string 2.4 cm long (about an inch) represents one year, for example, then a 183-cm length (about 6 feet) is equivalent to the average lifetime of a person living in the United States. A string representing all of recorded human history would be fully a kilometer long, but a piece representing 4.5 billion years would be 114,280 km long! Four and one-half billion quarters would form a stack nearly 8,000 km high. Can anyone fully visualize a string that would wrap around the Earth nearly three times, or a stack of quarters that would reach from here to the center of the Earth and halfway to the other side? ...
As staggering as these numbers may seem, the evidence clearly shows that the Earth's age is, indeed, 4.5 Ga, and the universe is probably three to four times older. Yet humans are relatively recent inhabitants of our planet and have witnessed only an infinitesimally small percentage of Earth's history. No man, no creature, no plant was present when Earth, her sister planets, and the Sun condensed from a shapeless cloud of primordial matter. How then can we peer back into these seemingly infinite reaches of time and calculate an age for the Earth that requires ten digits?
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