The physical models were open to question and, in retrospect, were naive. It became quite clear that many areas of the Earth had alternated between being land and being covered by seas, that there had been extensive slow sedimentation, that the mountains had not been created in situ as is but rather had a long history of slow deformation, and that long periods of erosion had shaped the Earth everywhere.By the early 1800's it was generally accepted that the Earth had a long history. The uniformatarians (Hutton 1788, Lyell 1830) pictured the Earth as being indefinitely old.There were various attempts to estimate the Earth's age, working back from sedimentation rates and other geophysical phenomena.The attempts produced estimates from about 100 million years up to several billion years. The first is that the geological history was still being reconstructed.Many authors choose to present the history of a complex subject by breaking it up into major threads and following the history of each thread separately.I have chosen instead to provide a chronology of significant works and their authors with a view to providing a sense of how perspectives on Geology changed over time.
This did not matter; the theological perspective did not require physical rationalization.The selections and comments here are not a complete exposition of the works of the authors mentioned; rather they were chosen to illustrate and exemplify changing perspectives over time.In Europe the issue of the age of the Earth was not a serious one prior to the rise of science; the history of the Earth was assumed to be accounted for in Genesis.It was not ruled out, per se, but it was not necessary. In the new science, however, rational explanation was desirable. In 1640 Ussher produced his famous calculation that the Earth was created in 4004 BC.In 1637 Descartes produced a cosmogony that was highly influential for more than a century. It was not in their estimates of the age of the Earth - Descartes retained the biblical date.The second is that the rates of the physical processes in question are variable and knowledge of them was incomplete.In the late 1800's physicists, armed with a more advanced physics than that available to Descartes, made new estimates of the age of the Earth and the Sun.Hutton and Lyell, who held that the history of Earth was dominated by slow relatively uniform changes in an Earth with a static over all history.During the early part of this period there was a considerable amount of activity by runs from AD 1850 to the present.If, in the year AD 1600, you had asked an educated European how old the planet Earth was and to recount its history he would have said that it was about 6000 years old and that its ancient history was given by the biblical account in Genesis.If you asked the same question of an educated European in AD 1900 you would have received a quite different answer.