The state of Arizona has a number of geologic oddities such as the san Francisco volcanic
field, the petrified forest, and the grand canyon.
However, there is another area with unusual rock formations which few in the state are
aware of.
In the southeast of the state are a grouping of tens of thousands of unusual columns of
rock, some of which appear to be standing rather precariously.
These columns are all part of an ancient supervolcano within the state, whose geologic activity
led to the formation of these unusual features.
The area in question is called the Chiricahua national monument, which may soon get upgraded
to a national park due to the area's unique geology and population of endangered species
such as ocelots and jaguars.
You heard that correctly, ocelots and jaguars...in Arizona.
This video will discuss the ancient supervolcano which formed all of these features, which
is called the "Turkey Creek Caldera".
The Turkey Creek Caldera is located in the southeast corner of Arizona, where it is 35
miles north of the border town of Douglas.
This caldera covers a vast area, and is approximately 12 miles or 19 kilometers wide.
The reason why this caldera exists is complex.
Around 40 million years ago, the Farallon tectonic Plate was subducting underneath the
North American plate at a very shallow angle.
Due to this shallow angle, very few volcanoes were created.
This process caused an extreme amount of compression, causing the uplift and formation of the rocky
mountains.
However, several million years later, something changed.
The Farallon tectonic plate suddenly snapped downwards at a much steeper angle in a process
called slab rollback.
This caused magma to rush upwards to fill the empty space previously occupied by the
tectonic plate.
Large volumes of magma than creeped through the crust, and erupted onto the surface through
incredibly large volume explosive eruptions.
This geologic event was referred to as the Mid tertiary ignimbrite flare up, which saw
the creation of dozens of supervolcanoes in a short timespan in the southwestern United
States.
Other supervolcanoes which erupted during this time period included La Garita near the
town of Creede, and Wah Wah springs on the Utah Nevada border.
Around 27 million years ago, one section of crust underneath Southeast Arizona built up
a large magma chamber.
This chamber eventually expanded in size to contain several hundred cubic kilometers of
magma.
As a result, an immense amount of pressure began to build.
Then, 27.9 million years ago, this pressure was released through a catastrophic eruption.
The size of this eruption was unimaginably large, as it was equivalent in size to 500
simultaneous eruptions of Mount Saint Helens in 1980.
As a plume of ash traveled more than 50 kilometers into the atmosphere, pyroclastic flows raced
across the surrounding landscape.
Although we aren't sure of the full extent of the eruption, these pyroclastic flows likely
traveled up to 100 kilometers or 62 miles away, resulting in an extreme level of destruction.
Then, due to the extremely high volume of material erupted, totaling about 500 cubic
kilometers of volcanic rock, a massive section of the volcano collapsed downwards to fill
the nearly empty magma chamber.
This formed a massive 19 by 15 kilometer wide caldera.
In total, some areas adjacent to the volcano had been covered by several thousand feet
thick of volcanic rock.
This volcanic rock included a mixture of pyroclastic flow material, rhyolite lava, and falling
ash.
Since then, the areas covered by locally thick layers of ash did not erode away as easily
as areas with thinner layers of volcanic rock.
Due to the strength of these rock types, this long term process of erosion by wind and water
formed tall vertical columns, some of which are more than 60 meters or 200 feet in height.
Some of these towering columns have quite a precarious look to them, as boulders on
top of them seem to be placed in a very unstable manner.
However, these boulders are quite stable, as they could be technically flipped upside
down like a stalactite and still remain due to the strength of the solidified rock.
Today, other unusual geologic features remain in the region.
These include natural volcanic arches formed by erosion, and unusual terrain which is called
"inverted topography".
Inverted topography is terrain which used to be at a low point, but now is a high point
in the landscape due to the resistance of rock there to erosion compared to nearby ground.
One example of this is the top of Rhyolite Canyon.
In summary, this fascinating region is worthy of becoming the next national park in the
United States, and has an abundance of wildlife.
I hope that you enjoyed this video!
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