The birth of life was the most momentous occasion in the history of the earth. When one considers the myriads of evidences unearthed by paleontologists and paleobotanists, they seem to leave no room to doubt the great conception that the life of the land has emerged from the sea. It is, therefore, only a natural impulse to look for the remains of this life in the rocks laid down by the ancient seas and to wonder at the vastness of time behind them. Since traces of the lowest forms of life have been found in practically the oldest known sedimentary strata, the problem of determining the age of life necessarily involves the determination of the age of those strata. But unravelling the dead past is not an easy task. One trying to unlock the “secrets of the cemetery of Nature’s dead,” walks on a shadowy road. His difficulties are many. It is like crossing a deep moat, climbing a steep wall. Various methods have been applied to estimate the age of different periods of the earth’s history and much progress has been made toward a successful issue. Broadly, the procedure of different methods is the same. They do not differ in principle. “The rates of certain changes at the present day are determined as accurately as possible, and in imagination, the respective processes are traced backward in time until limiting conditions are arrived at.” Until the epoch-making discovery of radium, the two most outstanding methods used in calculating geologic time were (1) the rate of land erosion and deposition and (2) the rate of derivation of salt (sodium chloride) from the land and its accumulation in the oceans. Theoretically, it is simple to use the rate at which sediments are being deposited or solutions gathered into the ocean, as “geologic clocks” for estimating the length of past time. But in practice each method encounters its own difficulties and the results deduced give us at best only a rough idea of the immensity of time involved. I shall not deal with these individual estimates, but give the mean of several, which is 100,000,000 years, speaking roundly. As stated before, it is only a rough estimate. Nevertheless, it confirms the fact that the earth is very old—indeed much older than is commonly believed. In 1650, Bishop Ussher, in his interpretation of the “In the beginning” of Genesis, estimated that the earth was created 4004 years before the birth of Christ. According to this view the earth is 5931 years old today. Many cosmogonists and even some geologists of the 19th century held this Biblical interpretation to be the age of the earth. Other ancient religions held that the earth was created much earlier then 4004 B.C. Hutton, one of the founders of Geology, in his studies, found “no vestige of a beginning—no prospect of an end.” One cannot help sympathizing with Hutton. Whoever has made a trip to the Grand Canyon of the Colorado River, Arizona, must remember the awe-inspiring depth of the Paleozoic strata and thousands of feet of Proterozoic