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TABLE OF CONTENTS
PAGE [Introduction] ix [Chapter I—The Archean Era] 1 [The Earth’s Oldest Rocks, Grand Canyon] 2 [Granite in Grand Canyon] 4 [Chapter II—The Algonkian Era] 5 [Algonkian Rocks in Grand Canyon] 5 [Formation of Mountains] 6 [Early Climates] 6 [Oldest Known Life] 7 [Chapter III—The Paleozoic Era] 9 [First Animal Life—The Tonto Rocks] 9 [The Missing Periods of the Third Era] 11 [The Age of Fish] 12 [Sea Life From the North—Redwall Limestone] 12 [Tracks in the Supai Sandstone] 14 [Landscapes of the Hermit Shale] 15 [Wind-blown Sand—The Coconino Sandstone] 17 [Warm Seas from the West—The Toroweap and Kaibab Formations] 18 [Chapter IV—The Mesozoic Era] 21 [Remnants of Younger Strata—Red Butte and Cedar Mountain] 21 [The Petrified Forest] 22 [Dinosaur Tracks—The Painted Desert] 24 [The Rocks of Zion Canyon and Rainbow Natural Bridge] 26 [From Seashells to Coalbeds] 27 [Chapter V—The Cenozoic Era] 29 [Bryce Canyon Formation] 30 [A Great Erosion Surface] 32 [Crustal Movement at Grand Canyon] 33 [Cutting the Grand Canyon] 34 [The Forming of Zion Canyon] 37 [Glaciers] 38 [San Francisco Mountain Volcanic Field] 39 [Elephants and Camels] 41 [Advent of Man in the Southwest] 42 [Bibliography] 45
ILLUSTRATIONS
PAGE [The Grand Canyon] Frontispiece [Diagrammatic Sections of Grand Canyon Region] x [Rocks of First Era, Inner Gorge of Grand Canyon] 1 [Block Diagrams of Events of First Era] 3 [Tilted Rocks of the Second Era, Grand Canyon] 5 [Diagrammatic Section of Third Era Formations, Grand Canyon] 8 [Scene on Cambrian Sea Floor in Grand Canyon Region] 10 [Trilobites Preserved in Green Shale of Grand Canyon Walls] 11 [A Fresh-water Fish of Devonian Age (Sketch)] 12 [Sea Life from the Redwall, Grand Canyon (Sketches)] 12 [Havasu Falls in Redwall Limestone, Grand Canyon] 13 [Tracks of Short-legged, Prehistoric Animal, Supai Formation, Grand Canyon] 14 [Landscape at Time Hermit Shale was Forming] 15 [Fossil Fern From the Hermit Shale, Grand Canyon] 15 [Wind-blown Sand, Coconino Formation, Grand Canyon] 17 [Tracks of Primitive Four-footed Animals, Coconino Sandstone, Grand Canyon] 17 [Marine Life From the Kaibab Limestone, Grand Canyon (Sketches)] 18, 19 [Diagrammatic Section of Fourth Era Formations, Southern Utah and Painted Desert Regions] 20 [Cedar Mountain] 22 [Red Butte] 22 [Petrified Forest, Arizona] 23 [Petrified Logs of Triassic Age] 23 [Dinosaur Tracks, Painted Desert] 24 [The Painted Desert] 25 [Zion Canyon, Navajo Sandstone] 26 [Rainbow Natural Bridge, Navajo Sandstone] 26 [Cretaceous Shells From Southern Utah (Sketches)] 27 [Coal Canyon, Painted Desert Country] 28 [Bryce Canyon] 30 [Map of Colorado River] 31 [A Great Erosion Surface] 32 [Diagrammatic Cross Sections of Grand Canyon] 35 [The Grand Canyon] 36 [Zion Canyon] 37 [Chart of San Francisco Mountains] 39 [San Francisco Mountain—Past and Present (Sketch)] 40 [Map of San Francisco Mountain Volcanic Field] 40 [San Francisco Mountain] 41 [Elephant and Camel Remains] 42 [Ancient Indian Petroglyphs, Head of Bright Angel Trail, Grand Canyon] 43
INTRODUCTION
Probably no place in the world of similar area has recorded a more complete or a more interesting resume of the earth’s history than has the high plateau country of northern Arizona and southern Utah. Although many great events and some long intervals of time are not represented by the formations of this region, yet of the five major chapters or eras into which all of time has been divided by geologists, at least some parts of each have left their traces in this area.
Whether on the brink of the mighty Grand Canyon, among beautiful logs of the Petrified Forest, or beneath the lofty walls of Zion—the “Rainbow of the Desert”—one looks upon rocks which are not alone curious or colorful, but which are also records of the past inscribed and illustrated in an intensely interesting manner. In one place is seen the sand of ancient dunes, in another the border of an early sea, or perhaps the floodplain of mighty rivers, and in all of these remain the unmistakable evidences of life—plants and animals preserved to make a reality of the living, moving past. Everywhere are found the evidences of those great processes of nature—erosion of the high country, land formation in the low country, and mighty crustal movements slowly raising or lowering the land in both.
From the rim of Grand Canyon one not only looks down through tremendous space, but also through time, glimpsing the record of vast ages, measurable not in centuries but in millions and even hundreds of millions of years. There in the bottom of that mighty chasm are found rocks formed during the first and oldest era—rocks in which the original structure has been entirely modified by great heat and pressure and in which no evidence of life has been found. There in the Grand Canyon are also seen two other great series of rocks, those of the second era which are partially altered and which contain earliest traces of plants, and those of the succeeding era in which are preserved primitive animals of many types.
