What We Did 250 Million Years Ago
at Grand Canyon
by "Canyon Dave" Thayer
Grand Canyon is magnificent, and you must see it to get that. But there
is much more, very much more, to its magnificence, if you glimpse the
invisible march of time here. 1.7 billion years are recorded in these
strata. Geologists attempt to find out what happened during all those years.
For example, from many viewpoints along the South Rim, I can see evidence of
roughly twenty times that different inland seas covered
this part of Arizona. The Colorado River had not yet dug this gorge.
Each of the seas covered the present location of Grand Canyon and several seas inundated much of Arizona
besides. Twenty times the
ocean encroached from today’s west, where Pacific breakers crash to shore, and each time we could have gone swimming
here. Each time the sea came, it stayed here for an average of 5 or 10 million years and when each sea finally made
its million year retreat, it stayed out for equivalent millions of years.
Not one person sailed these spreading seas—each soaking of Arizona ended by the time of Tyrannosaurus rex.
As a geologist, I would so enjoy visiting those lost seashores. So come pretend with me...
We are a tribe that lives where Grand Canyon lies now. One of the inland seas, let’s say the fifth, is here at your
feet. If you were to walk our beach, you could see our little huts up on the bluff to the east, above the shoreline.
Since the Grand Canyon is not yet here, one can walk the shoreline in either direction, north or south.
We can gather seashells—every sea had its own. Ours are orange brachiopods
and white snails. In years to come, professors will lay them out on tables,
fossils for their geology students. But for now, we fill our pockets. Our kids drop one from
their sandy hands for each new one gleaned.
Tonight, as twilight deepens, someone in our tribe suggests that we walk down the bluff to the sea. It is full moon
tonight, a time of great beauty and the broad ocean. So we line up along our worn trail and grope downhill to the shore.
As we arrive in the darkness, we feel and smell a familiar salty breeze blowing gently off the sea. There is a shushing
of invisible waves. And suddenly the huge full Moon pops over the eastern horizon.
Every wave turns to moonlit silver! One by one the waves boom onto the tall black rock. Each pearly plume makes its
own splash and spray. We are silent for a time, overcome by the beauty. We think to ourselves that this must be the
most gorgeous sight in the wide world.
And now someone asks, “Has this always been the ocean, and this the shore?” We laugh, “Of course, you silly! Our people
have lived here for 5,000 years. It has always been like this, and always will be.”