F Farming 30 Fishers Peak 23 Fissures 20 Forests 1, 2, 7 Fort Union Formation 16, 40 Fossils 16 Frio River 46 Front Range 43 G Gangplank 27 Gas 30, 47, 49 Glaciation 2, 5, 11, 33 Grand River 39 Great Bend, Kans. 2 Great Bend Plains 48, 49 Great Falls, Mont. 33, 35 Great Ice Age 5 Great Lakes 5 Guadalupe River 46 Gulf Coastal Plain 7 H Harney Peak 20 Havre, Mont. 33 Heart River 33, 35, 39 Hell Creek Formation 11 High Plains 7, 10, 25, 45, 48 Highwood Mountains 33, 35, 36 Horses 16, 18 Hudson Bay 32, 33 I Ice Age 5 Independence, Mo. 2 Interior Highlands 5 Interior Plains 5, 11 Interstate Highway 25 43 Interstate Highway 70 4 Introduction 1