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The Age of the Earth
This is a definitive, masterly history and synthesis of all that has been said (by theologians and scientists) and is known (to science) about the question, How old is the Earth? It explains in a simple and straightforward way the evidence and logic that have led scientists to conclude that the Earth and the other parts of the Solar System are not several thousand years old, as some today would have it, but four and one-half billion years old. It is a fascinating story, but not so simple as single measurement. Our universe is a large, old, and complicated place. Earth and other bodies have endured a long and sometimes violent history, the events of which have frequently obscured the record that we seek to decipher. Although in detail the journey into Earth's past requires considerable scientific skill, knowledge, and imagination, the story is not so complicated that it cannot be explained to someone who wants to know and understand the basic evidence. This book, then, has been written for people with some modest background in science, but at a level that will allow the material to be useful and accessible to those without a deep knowledge of geology or physics or mathematics.
- GenresScienceNonfiction
492 pages, Hardcover
First published July 1, 1991
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Displaying 1 - 8 of 8 reviews
December 28, 2009
This is a very nice treatment of the science behind geologic dating. The author describes in detail how the various schemes work, including, for instance, the Rb-Sr isochron method. Fortunately, the author does not shy from mathematical formulas, although only high school algebra is required to follow the arguments in full detail.
One might ask why such a book is necessary. To answer that question, one need only look at the results of recent public polls, such as the 2004 Gallup poll that found fully 45 percent of Americans agreeing that "God created human beings pretty much in their present form at one time within the last 10,000 years or so". Enough said. We need this book!
One might ask why such a book is necessary. To answer that question, one need only look at the results of recent public polls, such as the 2004 Gallup poll that found fully 45 percent of Americans agreeing that "God created human beings pretty much in their present form at one time within the last 10,000 years or so". Enough said. We need this book!
August 18, 2024
A GEOLOGIST ATTEMPTS TO EXPLAIN HOW SCIENTISTS COMPUTE THE EARTH'S AGE
At the time this book was published in 1991, G. Brent Dalrymple was Research Geologist at the United States Geological Survey; he has also written 'Ancient Earth, Ancient Skies: The Age of Earth and its Cosmic Surroundings.'
He wrote in the Preface, "The purpose of this book is to explain how scientists have deduced the age of the Earth... I have written the book, then, for people with some modest background in science, but I have tried to maintain a level that will allow the material to be useful and informative to those without a deep knowledge of geology or physics." (Pg. x)
He explains, "For the Pahrump dikes and sills... we can only conclude that the samples are of different ages, have not remained closed systems since their formation, or both. There is no way to determine the age of the rocks from these data... If we had made only a single analysis of any of the samples in Figure 3.10b our conclusions might have been quite different. It would have been necessary to make some estimate of the initial [Strontium] composition and then calculate a simple accumulation age ... for the sample. The chances are great that the calculated age would have been incorrect, but... we would have no way of knowing if it was. Thus, the isochron method, while more work because it requires multiple analyses, is worth the effort because it is self-checking." (Pg. 109)
He admits that "A somewhat surprising result was recently obtained for lava flows of the Komati Formation ... Sixteen incremental heating analyses ... gave plateau ages ranging from 3.11 += to 3.49... Because the rocks in the Komati Formation were extensively metamorphosed early in their history ... the authors concluded that the oldest ... plateau ages probably reflect the age of initial metamorphism, which occurred within 100 million years of emplacement..." (Pg. 183)
He also observes that "It is known from other evidence to be discussed that the Earth's age is most probably between 4.5 and 4.6 [billion years], yet the oldest rocks found on Earth are only about 3.8-3.9 [billion]. What happened to the rocks that represent the first two-thirds to three-fourths of a billion years of Earth's history? The answer to this question is not really known---there are only speculations and possibilities. One possibility is that during that period of Earth's history not only was the first continental crust forming, it was also being vigorously recycled and regenerated... The absence of known rocks that represent the first two-thirds to three-fourths of a billion years of Earth's history is probably due to destruction owing to vigorous crustal recycling., intense meteoric bombardment, lack of discovery, or some combination thereof." (Pg. 191-192)
He notes, "Of the radioactive nuclides not continually produced in the natural environment, only those with half-lives greater than 82 Ma presently occur in nature. Theory predicts that the missing short-lived nuclides should have been produced in significant amounts during nucleosynthesis, and the discovery of certain of their decay products of meteorites proves that they did once exist. The reason that the short-lived nuclides are missing is simply that the Solar System is old and they have decayed over time, so that their current abundances have fallen below the limits of detectability. Indeed, the missing nuclides demonstrate that the Solar System is some billions, rather than thousands or millions, or years old." (Pg. 393)
Rather more "technical" than he intended (his other book above is more for a "general" audience), this book will nevertheless be of interest to anyone wanting to know, "How do scientists know how old the Earth is?"
At the time this book was published in 1991, G. Brent Dalrymple was Research Geologist at the United States Geological Survey; he has also written 'Ancient Earth, Ancient Skies: The Age of Earth and its Cosmic Surroundings.'
He wrote in the Preface, "The purpose of this book is to explain how scientists have deduced the age of the Earth... I have written the book, then, for people with some modest background in science, but I have tried to maintain a level that will allow the material to be useful and informative to those without a deep knowledge of geology or physics." (Pg. x)
He explains, "For the Pahrump dikes and sills... we can only conclude that the samples are of different ages, have not remained closed systems since their formation, or both. There is no way to determine the age of the rocks from these data... If we had made only a single analysis of any of the samples in Figure 3.10b our conclusions might have been quite different. It would have been necessary to make some estimate of the initial [Strontium] composition and then calculate a simple accumulation age ... for the sample. The chances are great that the calculated age would have been incorrect, but... we would have no way of knowing if it was. Thus, the isochron method, while more work because it requires multiple analyses, is worth the effort because it is self-checking." (Pg. 109)
He admits that "A somewhat surprising result was recently obtained for lava flows of the Komati Formation ... Sixteen incremental heating analyses ... gave plateau ages ranging from 3.11 += to 3.49... Because the rocks in the Komati Formation were extensively metamorphosed early in their history ... the authors concluded that the oldest ... plateau ages probably reflect the age of initial metamorphism, which occurred within 100 million years of emplacement..." (Pg. 183)
He also observes that "It is known from other evidence to be discussed that the Earth's age is most probably between 4.5 and 4.6 [billion years], yet the oldest rocks found on Earth are only about 3.8-3.9 [billion]. What happened to the rocks that represent the first two-thirds to three-fourths of a billion years of Earth's history? The answer to this question is not really known---there are only speculations and possibilities. One possibility is that during that period of Earth's history not only was the first continental crust forming, it was also being vigorously recycled and regenerated... The absence of known rocks that represent the first two-thirds to three-fourths of a billion years of Earth's history is probably due to destruction owing to vigorous crustal recycling., intense meteoric bombardment, lack of discovery, or some combination thereof." (Pg. 191-192)
He notes, "Of the radioactive nuclides not continually produced in the natural environment, only those with half-lives greater than 82 Ma presently occur in nature. Theory predicts that the missing short-lived nuclides should have been produced in significant amounts during nucleosynthesis, and the discovery of certain of their decay products of meteorites proves that they did once exist. The reason that the short-lived nuclides are missing is simply that the Solar System is old and they have decayed over time, so that their current abundances have fallen below the limits of detectability. Indeed, the missing nuclides demonstrate that the Solar System is some billions, rather than thousands or millions, or years old." (Pg. 393)
Rather more "technical" than he intended (his other book above is more for a "general" audience), this book will nevertheless be of interest to anyone wanting to know, "How do scientists know how old the Earth is?"
June 23, 2017
As a geologist who specializes in radioisotope geochemistry, I loved this book. That said, I think that non-scientists might have a hard time understanding the nuances of much of this book. It might be just a touch too technical.
July 14, 2022
Incontrovertible evidence explained to a simpleton who didn't know much about radiometric dating. Very insightful!
September 19, 2015
This is my second go-round on this book. The first time I read it a few years ago I found it very hard going, perhaps because of the somewhat stuffy style (for a science book aimed at non-specialists), perhaps because I was not willing to put the work in that was required to understand some of the concepts. This time I approached it with more of a can-do attitude, and it payed off handsomely. This is not a book to be trifled with for someone with only a meager science background such as myself, and many times I had to stop and reread some of the equations and study the graphs carefully. The book is a bit dated, and the chapters on the age of specific earth rocks and meteors went into encyclopedic detail that I felt was unnecessary to the main point. Because of these two things, I gave this book three stars rather than four.
August 31, 2013
Excellent near the beginning and end, but the middle seriously bogs down in technicalities. Dr. Dalrymple meticulously presents a solid scientific argument, reminiscent of the Origin of Species. Both books tend to clobber the reader over the head with a vast mountain of evidence, which, although impeccable scientifically, does not make for light reading.
May 30, 2014
Awesome. If you've wondered how exactly scientists come up with the numbers for the age of the earth, and how they can seem so sure, read this book. Lots of hard data and careful explanation.
May 22, 2015
This was fantastic; struck the balance between details and readability.
Displaying 1 - 8 of 8 reviews