CHAPTER II. GEOLOGIC AGES. Formation of the Earth — Cooling of the Crust — The Various Periods as Outlined by Scholars — Appearance of Vegeta- tion — First Animal Life — Geologic Formations of Goodhue County — Influence of These Distance Periods on Modern Existence. !t was necessary for the earth to undergo many changes before it became suited for the habitation of man. According to the students, the globe was originally a mass of molten rock. The cooling process was undoubtedly a slow one, and the crust just under our feet did not become hard enough and cool enough to rest any superstructure on for perhaps many thousands of years. Probably many ages passed while it was a rough, ragged, irregular mass of granite — the skeleton of the future earth. Abrasion and erosion ground the surfaces of the mass into powder. Oceans swept over it. Chemical changes operated upon it. Next the sandstone was laid up. Then came the magnesran limestone of which our bluffs are composed. At this period fossil life begins. The reptilian age came on. The iethyosaurus. the pterodactyl, the iguanodon and plesiosaurus and other huge monsters wallowed and splashed in the muddy water. Then came the glacial period. The edges of the bluffs were polished and seamed by huge icebergs on their way down from the North. The Mississippi at that time covered a vast area. What are now towering peaks were then islands, scarcely reaching above the water. But the glacial period passed. Vegetation appeared. The earth rejoiced in scenes of beauty. Mammals came. Man, rude and uncouth, the contemporary of the mammoth and the cave bear, appeared on the scene, and the era of humankind commenced in primitive barbarity. Some years ago Prof. E. AY. Schmidt. M. A., of the Red Wing Seminary, was induced to write a short article on the geology of Eed Wing and the surrounding environs of Goodhue county. 11
