A good start to engaging with this post would be to click on the picture above the picture above to fully take in the landscape to the East-Northeast of The Valley of the Sun, below Four Peaks, the area the Yavapai people call Wi:khoba. Below that prominent landmark on Phoenix’s eastern skyline lies the rocky, red expanse around the Verde River, one of Arizona’s oldest, originating Southwest of Flagstaff and flowing 195 miles to connect with The Valley’s Salt River. Snow-covered for a week or two every Winter, as it was during our visit, the northernmost mountain of the four is called Brown’s Peak, the tallest at 7,659 feet, and highest point in Maricopa County. To the South is Weaver’s Needle and The Superstition Mountains (Yavapai Wi:kchsawa). Our aim more to the West was a short ramble through the Desert Creosote and looming Saguaro Cacti of The McDowell Mountain Wilderness area, the trail that leads to traces of The Marcus Landslide.
Discovered in 2002 by two Arizona State University students, the spot was named posthumously in honor of their teacher, Dr. Melvin Marcus, a geography professor at ASU and accomplished alpinist, academic and mentor. Scientist’s estimate The Marcus Landslide occurred approximately 500,00 years ago, when the climate in the area that today is known as The Sonoran Desert was vastly different than 77 degrees and sunny it was a few weeks back. Although ice actually never covered the area, it was much cooler and wetter during that time period. Speaking of cooler, the science of giant boulders and a mountain peak cascading across the landscape holds its own intrigue. But, like a wild west Anthony Michael Blowers nature walk, we were after the columns and worn rocks that are characteristic of weathered granite, mushroom-shaped forms that impressively towered over the desert landscape.
The mushroom-like features in the craggy slabs pictured above began as rectangular blocks of rock underground. Naturally occurring fractures in the granite defined the sides, edges and corners of the blocks. Water penetrated these fractures and over millions of years decomposed the granite into sand-sized particles. Because corners of the block are exposed to water from three different sides, they decompose faster than the faces or edges of the block. Similarly, edges decompose faster than faces. These different rates of decomposition produce rounded shapes. Erosion then removed the decomposed material around the block, eventually exposing the top at the surface. Water running off the exposed top soaked into the surrounding soil, further weathering the buried sides, edges and corners into a cylindrical shape. When erosion finally exposes the rest of the buried rock, the top-heavy mushroom shape emerges.
Voila! Stems and caps city. Some exposed rock may be top heavy and unstable, factors also playing a role in the massive ancient Landslide. Now that we’re closer to home, look for a more local stroll with Anthony in late April, currently in the works, as well as a magic Morel Mushroom hunt come early May, with our Spring schedule up and Flowering.
