The Grand Canyon's Emerald City

"We're off to see the wizard, the wonderful wizard of Oz" but - wait Toto! I don't think we are in Kansas anymore. Nor were we on the yellow brick road, but on the Grand Canyon's Hermit Trail, when all of a sudden we reached a layer that looked liked we had walked into the Grand Canyon's version of the Emerald City. It was the Bright Angel Shale which is the middle layer of the Tonto Group.

Because this layer, at least from the top of the canyon, appears to be relatively flat when compared with all the other layers, I was expecting this to be a stroll in the park. But, two things I learned in backpacking to the bottom of the canyon 1) nothing is close, and 2) nothing is easy. Even though we had backpacked nearly 8 miles down some pretty steep slopes, the going was not getting any easier. In fact, the last 2 trail-miles on the Tonto Trail were some of the most treacherous we had yet experienced. Sometimes the trail was less than 12 inches wide, was covered with loose gravel or shale, and slanting precariously with the slope. (That night in my sleeping bag, I kept dreaming of the trail becoming more and more narrow!)

But each layer had its own unique features and wonder (not to mention challenges). When we arrived in the Bright Angel Shale, it was like someone had placed emerald colored glasses on on us. Until this point, everything were shades of red, brown, and terra cotta. But, all of a sudden we were seeing green, not because of the plants, but because of the mineral glauconite. According to Wikipedia, glauconite is an iron potassium phyllosilicate (mica group) mineral of characteristic green color which is very friable and has very low weathering resistance. It is the iron-potassium bond that gives it the green color. A phyllosilicate is a sheet forming silicate mineral (think phyllo dough) that gives it the thin layers and forms a shale like structure and is indeed very friable, which we experienced with each foot step on the eroded particles. Glauconite is an authigenic mineral (which means it is generated at the place it is deposited) and forms exclusively in marine settings. Very unique circumstances are needed to form it especially in the quantity observed in the layer exposed by the Grand Canyon. In chemical terms, it is called a reducing chemical reaction in which the new chemical compound loses an oxygen atom but picks up an electron. Potassium is one of the common elements that can cause metals, such as iron in this case, to be reduced. But, there must be plenty of water and a good source of potassium. All of these conditions were present, during the Genesis flood. The volcanism that ruptured the fountains of the deep provided an ample supply of both water and potassium (in the form of both ash and magma). This precipitate mineral was one of the first layers to be laid down, and because it is authigenic it settled most likely right where it was formed.


It is amazing how God has placed testimonies all around us regarding the validity of His Word, the Bible. And He doesn't disappoint us like the Wizard of Oz - He is no fake but the real Creator and King of the universe. Whether we are working our way down the steep slippery slopes of the Grand Canyon or are navigating equally slippery conditions that life can often present, we can rest assured that His Word is true and reliable not just for geologic history but for all aspects of life here on planet Earth.


Your word is a lamp to guide my feet

and a light for my path.

Psalm 119:105

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