Monday, May 17, 2010

The genius of Inca masonry

During my travels in Peru, I found nothing more striking or elegant than Inca walls. Above you’ll find two examples. The first is in a street in the Andean city of Cuzco, once the capital of the Incas. The second is at Saqsayhuaman, an Inca fortress whose ruins today overlook the sprawl of Cuzco. Notice that the walls are not held together by mortar; rather they consist of large interlocking stones that fit like a puzzle. One can only imagine the labor and organization required for such precision. In a seismically active area, these structures have endured to this day – while many Spanish constructions in Peru since mid 1500s have collapsed. In some cases, the walls blend with the landscape, like a naturally formed jumble of rocks, to an extent that they do not seem constructed (the second picture for example). They have an austere, minimalist look which elevates their beauty even more.

The other distinctive feature of Inca architecture is trapezoidal doors and niches. As John Hemming writes in The Conquest of Incas:
Doors and niches were invariably built in trapezoidal shapes, with the sides tapering inwards towards the lintel at the top. This was a logical method for builders who had not discovered the principle of the arch. It reduced the length of the lintel stone and spread the thrust of the weight it supported. Rows of such trapezoidal niches broke the monotony of Inca walls. Sometimes the niches were the size of sentry-boxes, tall enough to accommodate a line of standing attendants, but more often they were smaller, sunk into the wall at chest height to form a row of convenient cupboard alcoves.

Examples above of a trapezoidal door (from Saqsayhuaman) and wall alcoves (from Machu Picchu).


Chandra said...

Interesting walls. For general walls are meant to separate, these look like retaining walls to me, please correct me if I am wrong.

Great post.

As a seismic/structural engineer perhaps I can learn here how a puzzle rather than a mortar takes care of the stuff, i.e. retaining ground. Last picture is interesting - ground movement can be seen on the right side, slowly, really slowly, parting the walls into decay.

Thanks again, for the post. Great.

Hari said...

Hi Chandra -- Glad you liked this post. Actually, I am not sure of whether these walls are retaining walls. In fact, your conclusions may be better than mine, since you have the background. I like this Wikipedia description of seismic resistance: "During an earthquake with a small or moderate magnitude, [Inca] masonry was stable, and during a strong earthquake stone blocks were “dancing” near their normal positions and lay down exactly in right order after an earthquake."