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Dear friends, I must admit it. I’m obsessed with stones, especially since moving to Colorado. Not only do I take pleasure and comfort in their magnificence, but I’m also hooked by the stories they tell – stories of radically different landscapes, climates, flora, and fauna. Stories of deep time and change that hold clues and possibly suggest solutions for a warming planet. One of my favorite stories, one I want to understand more fully, is about how the iconic Flatirons came to be. So far, I’ve learned that prior to the Rocky Mountains we know today, there was another mountain range in this area – the Ancestral Rockies. It formed more than 300 million years ago. At that time, Colorado sat near the equator with a warm, humid climate. Giant insects flew, and small fin-backed protomammals, reptiles, and amphibians crawled through forests of scale trees and towering horsetails. Bit by bit, over about 150 million years, streams, wind, and other erosive forces leveled that mountain range. Its sediments lay strewn across the plains. Over roughly 80 million years, layer upon layer of new sediments from new landscapes buried the remains of the Ancestral Rockies. Those landscapes included – a desert, a fiery inhospitable coastline, a swamp trod by dinosaurs, a shallow salty sea, and more. Under all the pressure and heat, the sediments transformed into unusually strong sandstone. When the region buckled up again about 67 million years ago in another fit of mountain building (orogeny), the sandstone remains of the Ancestral Rockies were pushed up to nearly vertical. More cycles of uplift and erosion sculpted the flatirons we see today. The much younger Rocky Mountains, which also underwent cycles of uplift and erosion spanning 67 to 10 million years ago, sit to their west. The Rockies are still rising! Though I don’t have all the details down yet (please excuse any errors!), I love this example of Earth's power to build, destroy, and build again on a momentous scale over eons. I’ve come to think of Mother Earth as an incredibly dynamic and creative artist, one who’s a master recycler. Her work is not done. One day, the flatirons won’t frame this area. It’s fun to imagine what might come next. Such geologic stories leave me with a new perspective. I feel new, small, improbable, and grateful to be exploring this amazing planet.
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