Tuesday, May 5, 2015

The Cathedral of Mexico Ciudad, La Catedral de Mexico: the Underground, el Subterraneo.

When we wrote the dateline of the construction of the Cathedral in this blog a few days ago, we mentioned that in 1573, Archbishop Moya de Contreras organized the groundbreaking ceremony, as they started construction on the second Cathedral, the Cathedral that still prevails. What we did not mention was the magnitude of the challenge that the foundations of the Cathedral represented during the first years of the construction, and the ingenious methods these architects developed.
The most important problem at hand was that the building site, the Grand Tenochtitlan, was not dry land, but something of a manmade landfill, similar to building on the Great Canal in Venice. As we all know, the solution in Venice was to use wood pilings,  very long and strong tree trunks the Venetians brought by water from the forests of Slovenia, Croatia and Montenegro. Afterwards they buried the tip deep into the mud at the bottom of the canal. Yet after so many years, why haven't the pilings rotten, like the pilings of some many piers we see close to the sea?

The view from the Piazza San Marco towards the island of La Giudeca, Venice
The trick in Venice was that the pilings are so deep that the wood never comes in contact with oxygen, and therefore cannot rot. On the contrary, with so much contact with mineralized water, the pilings tend to petrify over time.

Estela, my wife, standing on the balcony of the Violino d Oro Hotel overlooking the canal in Venice

The Aztecs had faced this problem when they built the Great Tenochtitlan decades before the conquest. The problem was even more acute in Xochimilco, where even today, the residents live not only on the lake shore, but practically on top of the lake. At the point, the Aztecs found a type of tree they not only does not rot in water, it requires water so as not to rot...the Ahuejote, a willow tree that grows in central and southern Mexico.

Inspecting 400 year old Ahuejote, the wooden pilings underneath the Cathedral of Mexico

Last April, we took a group of 7 adults, down inside a dig, that was done several years ago, to outset the sinking of one of the corners of the Cathedral, that was sinking quicker than the other three corners. The group of architects corrected the problem, but discovered some long forgotten secrets on the construction of the Cathedral...the ahuejotes or wooden pilings the XVI century Spanish architects used to build a solid foundation.

The Ahuejote was not the only discovery the architects made. They discovered two pyramids that had been forgotten...the Pyramid of the Wind and the Pyramid of the Sun, as well as the glifo, showing the four cardinal points, and the fifth, which is the zenith.

The ruins of an minor Aztec Pyramid buried and forgotten for almost 500 years.

The glyph or glifo showing the four cardinal points and the center point or zenith

As we changed our angle of view, the polychromatic coloring of the Glyph changed tones.

As we continue to change our angle of view, the tones of the Glyph also change.

A wooden Ahuejote is anchored in the buried pyramid to support the foundations of the Cathedral

Hydraulic jacks used to correct the sinking of the fourth corner of the Cathedral 

Another hydraulic jack used in correcting the sinking corner of the Cathedral
Our expedition came to a startling conclusion. The hydraulic jacks you see above were not required because the ancient ahuejotes no longer were up to the task. The ahuejotes did start to rot over the last 40 years, but not because they were exposed to water, but to the contrary, because of the lack of humidity in the subsoil of Mexico City, that over the past generations has exhausted its well waters. The question remains whether the hydraulic jacks can last as long as the ahuejotes have.

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