OCR Text |
Show Beds of Clay Reveal the Passage of Time Geologists can follow the tracks of the sun und tell the time, year by year, in geological ages so ancient that even by millions of years they are hard to count. Not tar from Stockholm there are some remarkable beds of clay, regularly regu-larly arranged In alternating bands of sand and clay. These turn out to be the layers deposited by the melting melt-ing glaciers of the Ice age, each one laid down In the spring and summer when the sun was hottest And as there was a freeze-up each winter and melting each summer, the layers become be-come almost as accurate an Index to the antiquity of the Ice age as the annual an-nual rings ot a tree are to the age of the tree. Moreover, the same system of measuring meas-uring geological time has now been extended over all Scandinavia, and parts of India and Soulh America. Everywhere the layers appear to cor respond so closely In the variations ot their thickness, year by year, that there seems no doubt they were laid down in corresponding years. Baron Gerard de Geer. |