Now we come to Glacier National Park. Within its boundaries there perhaps is exhibited a greater variety of geologic features than in any of the others. Much of the park lies above timberline so that the rocks which comprise its mountains are exposed to view. Held within these superb mountains is an entertaining geologic story which they are anxious and willing to tell us. All we need to do is unlock the door with the key the geologist gives us and then go see for ourselves. Why do the mountains rise so precipitously above the plains? What is that conspicuous black band across the faces of so many of the peaks, and how did it get there? Why are some of the rocks so red? The answers to these and other questions come out as the geologic story unfolds. The American people are interested in this story for they realize that to understand what they see is to increase their enjoyment thousandfold. Chart of Geologic Time (FOR A CHRONOLOGICAL ORDER OF EVENTS, THE CHART SHOULD BE READ FROM BOTTOM TO TOP) ERAS PERIODS DATES EVENTS IN GLACIER PARK AREA CENOZOIC The Present Post Glacial Erosion of the mountains; formation of alluvial fans and talus cones. 15,000 B.C. Pleistocene Birth of modern glaciers. Appearance of present forests. 1,000,000 B.C. Pliocene Extensive glaciation. Formation of lakes, waterfalls, horn peaks, cirques. Valleys scoured deeply by glaciers. Miocene Disappearance of forests. Oligocene Mountains worn down, raised, eroded again. Eocene Lewis overthrust probably occurred early in Eocene. 58,000,000 B.C. MESOZOIC Great mountain building (Rocky Mountain revolution) by forces which eventually formed Lewis overthrust. Sea withdrew and never again returned. Thick accumulation of marine sediments. Invertebrates abundant in sea. Expansion of the sea. Cretaceous 127,000,000 B.C. Jurassic Triassic Dinosaurs probably inhabited park and nearby area. 182,000,000 B.C. PALEOZOIC Seas covered region during much of era. Permian Carboniferous 255,000,000 B.C. Devonian Silurian Ordovician Cambrian 510,000,000 B.C.