The Rocks Don't Lie: A Geologist Investigates Noah's Flood Read Online Free PDF

life in the tracks and burrows preserved on paper-thin layers of stone. Here was proof of an ancient seabed made from slowly accumulating mud in which animals crawled, foraged, and died. People more patient or lucky than I in inspecting these rocks have found trilobites, distant cousins of spiders and crabs that roamed the seas from 515 million years ago to when they perished in the Permian Period, almost 200 million years before the demise of the dinosaurs.
    Pausing on the gentle terrain of Indian Gardens offered me a panorama of grand vistas. Yet the far rim lay out of sight. As I surveyed the staggering expanse of the canyon, it was hard to fathom how long it would take to erode the cliff at the canyon’s edge back beyond the horizon, one rockfall at a time.
    Lingering in the tree-shaded oasis of Indian Gardens, I reflected on how people see the land in different ways. More than rocks and topography, beliefs and experiences have shaped attempts to explain the formation of the Grand Canyon. People living along the canyon were curious about how it formed long before geologists and creationists formed their views.
    Like the Tibetan villagers along the Tsangpo, Native Americans living along the Colorado River have stories about a giant flood. A Havasupai story attributes the carving of the Grand Canyon to a catastrophic flood that occurred when the mischievous god Ho-ko-ma-ta unleashed a tremendous rainstorm. Another, more thoughtful god, Pu-keh-eh, put his daughter in a hollowed-out log to save her from the monstrous current rushing down to the sea. After the floodwaters receded, she crawled out from her improvised vessel and became the mother of all humanity. The story shares the same broad outline as that of Noah’s Flood—only with a matriarchal figure.
    Still soaking up the geologic story, I began climbing again toward the canyon rim. At the far end of Indian Gardens the shale gave way to the Muav Limestone, a section of carbonate rock sitting directly on top of the Bright Angel Shale. The sequence of sandstone, shale, and limestone I had just walked told me that the water deepened over time. At the upper boundary of the Muav Limestone, another unconformity lies at the base of a formidable cliff. This gap in the rock record documents another hundred million years lost to erosion above sea level.
    What you find directly on top of the Muav Limestone depends on your location in the canyon. From where I was, the trail snaked up a looming wall of red-stained rock rising several hundred feet upward. Climbing through a slot in the dark cliff, the trail followed a fractured zone in the aptly named Redwall Limestone. Along the trail I spotted clamlike fossils, evidence that life in the rocks was starting to become more visible, more complex, and more familiar. Yet another unconformity lies atop the Redwall, this one perforated by caves and sinkholes that formed when percolating rainwater dissolved soluble limestone and made a Swiss cheese–like landscape. This unconformity represents another 25 million years between the deposition of the Redwall Limestone and the overlying rocks of the Supai Group.
    Once above the cliff, the trail crossed back and forth countless times from siltstone to sandstone to siltstone and back to sandstone again. I was climbing a geological staircase made of shale treads and sandstone risers. Each step recorded the rise and fall of an ancient sea, with harder sandstone forming cliffs, and weaker shale forming gentle ledges. This means that the ancient sediments turned to stone before the canyon carved down into them. If the now solidified rock had been wet and loose when the canyon was cut, the canyon walls would reflect the strength of loose sediment rather than that of the rock. The sandstone would not hold cliffs because loose sand can only support slopes of at most 30 to 40 degrees, as you can see for yourself in the produce section of any grocery store by pulling an orange from the bottom of the