Cusco, Peru – Markets, Ruins, and a Geologic Puzzle

During the 14th century, the Inca ruler Inca Pachacuteq (Tito Cusi Inca Yupanqui) transformed the central Andean area of present-day Cusco, Peru into a major urban center. The city became the capital of the Inca empire, containing religious and administrative areas that were surrounded by fertile agricultural expanses. In the 16th century, the Spanish conquered Cusco, building their Baroque churches and palaces atop the remnants of the Inca city. Today about half a million people live in Cusco. The city is now known for its amazing indigenous population and as a mecca for tourists that travel on to the Sacred Valley and Machu Picchu.

The Plaza de Armas in the UNESCO World Heritage site of Cusco. Our guide told me that there is a celebration in the square 360 days of each year!
The Plaza de Armas in the UNESCO World Heritage site of Cusco. Our guide told me that there is a celebration in the square 360 days of each year! I actually saw three different events there during my first afternoon in Cusco, so needless to say, the Plaza de Armas is a busy place.

Cusco Historic District

Cusco was declared a UNESCO World Heritage site in 1983 and the boundary for the site is mostly what is known as the Historic District (link here for a map of the UNESCO inscribed property). I did tour some of the buildings within the Historic District, my favorite being the Convent of Santo Domingo. The Spanish built this church on the remains of Qurikancha, a revered Incan temple for the Sun God Inti. The Inca stonework is the foundation for the cathedral and it is truly enthralling to see. Interestingly, numerous earthquakes have extensively damaged the cathedral, but the Inca stone walls still stand largely undamaged.

Convent of Santo Domingo built over the Qurikancha.
My guide, Ayul Acuna Cardenas, explaining the Incan stonework.
My guide, Ayul Acuna Cardenas, explaining the Incan stonework that was part of Qurikancha and now forms the foundation for the Convent of Santo Domingo.
The trapezoid-shaped windows that are characteristic of Inca architecture.
The trapezoidal windows that are characteristic of Inca architecture.

 

 

 

 

 

 

 

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All kinds of goods are sold at the Vino Canchón market!
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The chili selection at Vino Canchón is simply superb.
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Vino Canchón’s fruit aisle is paradise for fruit lovers.
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What a selection of cheese!
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Many hotels get their fresh flowers daily from the Vino Canchón market.
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The prepared food at Vino Canchón is a must to try!
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The many varieties of Peruvian potatoes are overwhelming.

 

The Vino Canchón Market

The markets of Cusco – now they are an experience that can’t be missed. If you love food, Vino Canchón in the district of San Geronimo, is the place to go. This is the largest market in Cusco, supplying families as well as businesses with all kinds of produce, hardware, flowers, and many other items. It is also a market where the traditional Quechua language dominates the conversations. The Vino Canchón market is open daily and vendors are happy to talk with customers and the inquiring tourist.

Saqsaywaman and Its Geologic Puzzle

Saqsaywaman is the ruins of a fortified complex located at the northern edge of Cusco, on a hilltop that overlooks the city. As briefly summarized by Lake and others (2012):

“Most of the complex was demolished by Spanish settlers, who used the Incan stone to rebuild Cusco into a Spanish colonial town. What remains of the Saqsaywaman complex are large limestone blocks along with some shales, plasters and limonites which were too large for the Spanish settlers to easily remove. Some of these blocks are over 125 tonnes. Chroniclers state, that the construction ofSaqsaywaman was initiated by the ninth Inca, Pachacutec and was continued by his son Tupac Yupanqui Inca, between 1431 and 1508. The construction of Saqsaywaman is testament to the stonework engineering ability of its builder architects: Huallpa Rimachi Inca, the first and main Builder, followed by Maricachi Inca, Acahuanca Inca and Calla Cunchuy Inca. The remaining walls lean inward, which according to current theory allowed the Inca to create a more earthquake resistant structure, and are comprised of mortar-less joints so closely interlocked that even a single sheet of paper cannot fit between the blocks.”

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Remnants of fortress walls at Saqsaywaman include large limestone slabs, some weighing over 125 tons.
A close view of the rock slabs showing indentations at slab bottoms which may have been used in a leverage process during fortress construction.
A close view of the rock slabs at Saqsaywaman showing indentations at slab bottoms which may have been used in a leverage process during fortress construction.

 

 

 

 

 

 

The Geologic Puzzle at Saqsaywaman

On the north side of the Saqsaywaman Archeological Park is a strange outcrop. The outcrop is andesite, but it is marked with north-east trending grooves. It is so deeply grooved in fact, that it’s known as “El Rodadero” – the roller coaster.

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Close-up view of “El Rodadero” grooves in andesite.

In a quick scan of the geologic literature, it appears that ideas for groove formation have ranged from glacial grooves, to faulting, and to the andesite being plastic to partially molten as it was extruded and basically corrugated due to the overlying wallrock. The consensus on groove formation appears to be that of the viscous flow model, but here are links to the references I found, so decide for yourself:

  1. Spencer, J. , 1999,
  2. Spencer, J., 1999: Geology; April 1999; v. 27; no. 4; p. 327–330 (the complete article for the above abstract,
  3. Feininger, T, 1978: Geological Society of America Bulletin, v. 89, p. 494-503 (the initial article), and
  4. Schopf, J.M., 1979: Geological Society of America Bulletin, Part I, v. 90, p. 320, March 1979 (discussion on Feininger’s 1978 article).