But first a little prehistory:
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| Formations in La Garita Caldera |
A few years ago, about 28 million or so, a volcano
erupted in what is now south central Colorado.
By the time it had erupted at least 7 times over a 1.5 million year
interval a total of about 1,200 cubic miles of volcanic debris, enough to fill
lake Michigan, was piled several hundred meters deep over an 11,000 square mile
area and the ash fall covered a significantly larger area. Then it went dormant.
To put it in perspective it was 100 million times as
powerful as Mt. St. Helens. This was the
La Garita Caldera Super Volcano the 6th most powerful volcanic
eruption in geologic history. This single
ancient caldera exceeded, in total, the eruptions of the Yellowstone caldera and
La Garita was only one of multiple volcanoes within the San Juan volcanic field. Within that debris field is the area in
which the Denver and Rio Grande San Juan Extension is situated. It should be remembered this ancient volcanic
event occurred over 20 million years before the more recent events at
Yellowstone commenced. The last volcanic
event in the San Juan Volcanic Field was the relatively minor eruption of Los
Mogotes volcano lasting 3,000 years or so and that was more than 4 million years
before Yellowstone.
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| Rio Grande Rife Near Taos, NM |
After La Garita nature began the process of eroding the slowly
uplifting landscape to that seen today in northern New Mexico and Southern Colorado.
The uplifting of the Rockies was
through the process of plate tectonics which in which a series of smaller
plates slid under the North American Plate – subduction. As the surface rose the crust stretched and
in one spectacular instance split and spread creating a rift varying in width
from the San Luis Valley of Colorado on the north to a narrow cleft running as
far south as Mexico. The rift carries
the name of the major river that drains a large portion of southern Colorado, New
Mexico and Texas, the Rio Grande River.
When riding the Cumbres and Toltec one crosses the rift which is far
below the surface of the San Luis Valley.
But, that’s not our story today.
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| Pantheon |
Before we start, please keep in mind the greatest
contribution to construction invented and passed on by the Romans. It was a mixture of volcanic ash, pumice and
small sharp stone mixed carefully with water in a big bucket, thence poured
into a form to eventually harden. One of
the most amazing structures constructed by this method is the un-reinforced Pantheon
in Rome, which is still standing after nearly two thousand years. You know it as concrete.
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| Phantom Curve on the C&TSR |
Phantom Curve on the Cumbres and Toltec (Mile Post 312.30 –
by the way all mileage on the Cumbres and Toltec is calculated from Denver but,
that too is another story – earned its name from the ghostly shifting shadows
cast from the locomotive headlights of trains as they traversed the Curve at
night. The gnarled spires are eroded
layers of volcanic rock protected by
hard cap of breccia (“Bresh’-ah”). Breccia
is a hard congregate (“cement like structure") consisting of volcanic ash,
pumice and small sharp stones – sound familiar?
As the ground erodes small fissures opened through which hot water
flowed across and into the ground forming, in places, a breccia or tuff layer –
“tuff” is the same basic mixture as breccia but the stones are smaller and less
angular. Then millions of years of
water, wind and freezing eroded the material surrounding these areas where
breccia or tuff caps shed water away from the underlying geologic structure. A really glorious version of this geological activity is evident to those living in the west routinely see flat
topped plateaus, and mesa's, with flat tops and sloping sides to a lower plane. These are structures with breccia or tuff cap around which with the surrounding land eroded away. Those living in the Midwest, as we do, do not
see such structures because our geological history does not generally include the geological activity associated with such structures.
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| Bryce Canyon - Hoodoos on steroids |
Where the water erodes a place where a spire results, such as
Bryce Canyon National Monument, you can see vast areas of these eroded spires
looking vaguely like a creepy people which are called Hoodoo’s. In Toltec Canyon there
only a few hoodoos which are a reminder of a violent geological events in a far distant time.
So why are they called “Hoodoo’s”? Good question and this, which is loosely paraphrased, is probably as good an
answer as anything else:
In the a range of mountains in Arizona there are ridges of pinnacles with caps of tuff which local Apache peoples call Hoodoos. It seems they liken them to human figures which formed when the creator loosed a great flood. This corresponds to the universal flood story that is evident in nearly every human society, including Christianity. This legend was based on the idea that the creator favored the Apache people above all and as such provided protection for them. Some greedy people took advantage of this gift by rushing for protection while leaving children, women and elders behind. In anger, so the legend goes, the creator turned all the evil doers into stone as they stood on the ridges. So according to this legend the hoodoos are petrified people who unjustly abandoned the weak in a time of trial.
Regarding both Bryce Canyon National Park and Cedar Breaks National Monument, which also has a large display of hoodoos, Wikipedia adds this:
"The Paiute in the area developed a mythology surrounding the hoodoos (pinnacles) in Bryce Canyon. They believed that hoodoos were the Legend People whom the trickster Coyote turned to stone. At least one older Paiute said his culture called the hoodoos Anka-ku-was-a-wits, which is Paiute for "red painted faces"."
