during one winter and each light layer during one summer. By such detailed studies, it has been determined that it has taken, approximately, 5,000 years for the glaciers of Sweden to melt back 270 miles, and it is further known that this melting took place 8,500 years ago. We know that the glaciers in North America extended into the northern part of the United States and reached as far south as the Ohio river. We know that now their southern edge lies far to the north in northern Canada over a thousand miles away. We know that it took approximately 4,000 years for the continental glacier which last covered the New England states to melt back from Hartford, Conn., to St. Johnsburg, Vt. This is only one way of measuring in years some of the more recent happenings. There are many more methods that could be given if it were necessary.
In connection with evolution, it is especially of interest to note that the relative ages of the rocks correspond closely to the degrees of complexity of organization shown by the fossils in those rocks. The simpler organizations being found in the more ancient rocks, each type of organism becoming more and more complex as we come nearer to the present day, man and his fossil and cultural remains being no exception.
It, therefore, appears that it would be impossible to study or teach geology in Tennessee or elsewhere, without using the theory of evolution.
By Kirtley F. Mather,
Chairman of the Department of Geology of Harvard University.
(Biography—Kirtley F. Mather graduated in 1909 from Denison university, a Baptist college at Granville, O., in which evolution has for years been taught by every science teacher. In 1915 he received the degree Ph. D. from the University of Chicago. He taught geology at the University of Arkansas for three years, at Queens university, a Presbyterian institution at Kingston, Ontario, for three years, and from 1918 to 1924 he was head of the department of geology at Denison university. In 1923 he was appointed professor of geology at Harvard and has recently been made chairman of the department of geology at Harvard. He has been a geologist of the United States geological survey for many years, and has made geological examinations for various oil companies in Bolivia, Peru, Mexico, Canada, etc. He was for several years a trustee of the Baptist church at Granville, O., and chairman of the Baptist church at Newton Centre, Mass., and teacher of the "Mather class" in Bible school of that church. He is a fellow or member cf such scientific organizations as the Geological Society of America, the American Academy of Arts and Sciences, and the American Institute of Mining and Metallurgical Engineers. In 1923-24 he was president of the Ohio Academy of Science. He is the author of numerous scientific publications and bulletins of the United States Geological Survey, dealing with the petroleum resources of Kentucky, Oklahoma, Alaska and Colorado; technical papers on geology, paleontology and evolution in scientific journals; "Christian Fundamentals in the Light of Modern Science," etc. In 1919 he prepared a bulletin of the Tennessee Geological survey, dealing with the geology and oil resources of Summer county, Tennessee.)
The facts of life development are so numerously displayed and so evident in the rocks of the earth's crust that every geologist with whom I am acquainted has accepted the evolutionary principle as demonstrated. Much of the exposed part of the earth’s crust is composed of rocks deposited in layers as sand, mud, gravel or limestone in the seas, takes, or ponds of past time, or upon the surface of the dry land. These are in many places broken through by masses of rock which has formed by solidification of molten lava. The successive ages of the various kinds and formations of rock are determined by their physical relations.
