Geology 101

Sample rock, on the Trail of Time,
from one of the deepest layers
of the Grand Canyon.

Over the years, a quick check suggests, I've posted five times about my trips to the Grand Canyon.  Perhaps I've exhausted the topic.
-- "Confused Ideas," May 6, 2015

Well, maybe, but after two more posts last year, I can now say I've posted seven times about the Big Gulch, and here's number eight. 

I returned last night from another visit to the South Rim in what is becoming something of an annual encounter with nature and another test of my aging endurance.  I had planned to descend the South Kaibab trail to the Tonto Plateau, traverse the plateau for a couple or three miles until it ran into the Bright Angel trail, and then ascend by that now-familiar route.  But the combination of a little mild illness and gusty winds at the canyon led me to rule out the South Kaibab descent -- which is steep and, following a ridge, is exposed to the elements. 

Instead, I once more did the simpler Bright Angel Trail round trip, down to Indian Garden on the plateau -- a 3,000 foot descent and a ten mile round trip.  For those who have never done even this fairly easy descent into the canyon, I do recommend trying it in April rather than May or later.  The ease of the climb back up seems to depend more on the temperature than it does on your level of conditioning.  And Sunday, when I did my excursion, was a pleasantly cool, albeit sunny, day for a hike.  Extremely pleasant, allowing me to return to the rim with leg muscles aware they had been taken on a walk, but not suffering from exhaustion.

For the first time, I had booked accommodations early enough to grab a room at the Bright Angel Lodge (its "Prescott Lodge" annex, actually), so when I arrived back at the rim I was able to immediately collapse right at my doorstep.   Inexpensive, but rooms book early, even for April, before the high season begins.

What do you do at the Grand Canyon?  Assuming you're not force-marched to the rim by a tour conductor, and given one hour to snap your selfies before continuing on to Zion or wherever else you're scheduled?  In order of importance -- (1) let yourself be awestruck by the immensity and beauty of the canyon at different times of the day, camera in hand; (2) test your determination and endurance by trying hikes of various lengths into (or -- at least -- along the rim of) the canyon.

And after you've enjoyed those activities -- maybe on your second or third visit, depending on your interests and enthusiasms -- (3) learn something about the geology and time scale of the canyon.  And -- as I may have enthused in an earlier post -- props to the National Park Service for their excellent presentation of both.  The museums and signage are excellent, and most impressive of all is the "Trail of Time" -- a 2.83 mile portion of the Rim Trail marked so that every meter (yard) walked represents another million years of canyon development that has passed. 

As one walks the entire trail, he gathers an intuitive feel for just what one means when he says that an event happened a "billion years ago" -- that billion years is represented by one kilometer of walking, thank you -- and a sense of humility when he sees what an insignificant period of time homo sapiens has existed on earth.  Moreover, every fifty million years or so, the time marker is accompanied by a large sample of the rock formed during that period of the Grand Canyon's geological formation.  Each rock sample is large, and polished on one side; the observer is invited to feel it and get a sense for its texture.

Together with the rock samples and the time line, signs at various points explain how various rocks and minerals were formed during the area's history -- how the deeper rock of the inner canyon is extremely hard metamorphic rock formed under extreme heat and pressure, and has been eroded in a steep, narrow canyon by the river; how this metamorphic layer is covered by numerous layers of various softer sandstones, formed as lakes and seas covered the metamorphic layer in more "recent" times, eroding away to form wide canyon walls of varying steepness, depending on the hardness of the mineral at each layer.

But, perhaps I bore you? 

But the "Trail of Time" will not, and your first or your twentieth visit to the Grand Canyon will be enhanced by the painless lessons in geology and in the vastness of time that the canyon -- and the National Park Service's narrative -- will offer you.

I, for one, will be back again.