There
is a geologic zone in the Grand Canyon scientists call the Great Unconformity
but I have a friend that prefers to call it the Freaking Magnificent Great Unconformity. I just got back from the Grand Canyon where I rafted from
Lee’s Ferry to Phantom Ranch. A story is on its way about the Grand Canyon even though it's not exclusively from the Grand Canyon. I thought about
this on the river often.
1.7 billion years ago, the earth had mostly cooled and the part of the earth we now call northern Arizona was likely under the sea but it isn't known. There strata in the inner gorge is composed of Zoroastrian Granite and Vishnu Shists, igneous rocks from the mantle of the earth. All those rocks with Hindu names haven’t done a damn thing in the last billion years or so except rise and fall with whims plate tectonics. Life wouldn't be around for a long time. When life rolled around at about 600 million years ago, Northern Arizona was under the sea. Sedimentary rocks formed on top of the shists and granites and they have microscopic fossils. As you walk up canyon the fossils get larger and more complex. There are “unconformities” in the layers that are basically places where millions of years are missing. The Great Unconformity is a place where 545 million year old Tapeats Sandstone rests on top of the Chuar group of Pre-Cambrian Rocks dating 825 million to a billion years old. Either no rock formed for about 400 million years or rock formed that was later eroded away. Either way, eons disappeared from the geologic story. There is a side canyon of the Grand called Nautiloid Canyon with fossilized nautiloids like those on my tattoo. Higher up in the canyon there are dinosaur fossils in places. After that evolution tottered. Life hasn't improved. Nothing tops the Velicoraptor, present company included.
Nautiloid
Fossil, Nautiloid Canyon.
Time
moved along and the sea floor rose and the Colorado River was born as a
meandering tropical river on a vast coastal plain much like the Amazon today. With time, the North American Tectonic Plate rose to
7,000 above sea level. The river stayed put at lower elevation but the land
kept rising. The Grand Canyon was cut much like if you placed a knife on
top of a cake and lifted the cake with the knife not moving. The river didn't
cut down a mile deep but it did cut. The Kaibab Plateau rose and the river
stayed put.
Sometime after the mastodons went extinct and before the humans go extinct, I came along and rowed down the river in a rubber raft. I got back a few weeks ago. How is that act of running a river or my existence important in a grand scheme (pun intended) that includes Nautiloid fossils encased in rock for 300 million years?
Once
you find out you’re meaningless,
you want to spend as much time under a
waterfall as possible.Sydney at Stone Creek Falls
Every
night I laid on the ground looking at stars so old and so far away that some of
them could have died back when the velociraptors went extinct. The entire time
span of the human race is VASTLY shorter than the Great Unconformity. Millions of
species rose to existence and went extinct leaving no noticable trace of
their existence. For a moment chew on
the thought that eons can vanish from the face of the earth and that humanoids
have been around for about 2 million years.
Life is short, do this whenever you can. Elevs Chasm.
My
life matters a lot but only to me and to others that care about me. The
universe is too big and the fossils too old to fret too much about the details.
In the
vicinity of the Great Unconformity.
Tomorrow surgeons
fix my shoulder but it involves considerable cutting. No climbing for me for a
while. Maybe when I can climb again, I will head to one of the side canyons
with Zoroastrian granite. Granite is dumb as a rock but in climbing granite
that has been there for 1.7 billion years, we can gain wisdom.
I
took this photo east of Phoenix near the Superstition Mountains. I drove by the
sign, turned around, parked, and took photos of the sign from all angles.
Zoroastrian Granite, Grand Canyon
1 comment:
Great read Carlos! It brings back memories of the rocks in the canyon. You’ll climb again! ER
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