INCA ARCHITECTURE: THE `T’ GROOVE; SYMBOL, GOLD OR BRONZE?

INCA ARCHITECTURE: THE `T’ GROOVE; SYMBOL, GOLD OR BRONZE?

Gary R. Ziegler

T shaped grooves or sockets fitted with bronze clamps in stone building blocks at Tiahuanaco in Bolivia have been long known. At the site of Pumapuku, a number of grooves remain in place, Aligned back to back with adjacent blocks. Several examples of matching arsenic bronze clamps have been located and studied.

Curiously, the Inca adapted something similar some 500 years later. This in itself is not unusual as the Inca, inheritors of several thousand years of cultural development in the Andes, borrowed styles, technology and traditions from their cultural predecessors. What is noteworthy is that the grooves appear to be limited to important ceremonial or monumental structures.

T shaped grooves similar to Tiahuanaco can be found at the Coricancha Temple in Cusco, the temple hill at Ollantaytambo and at Nusta Espana (Yuroc Rumi) in the Vilcabamba. The T grooved blocks at the Coricancha contain U shaped, double T, and other shapes as well. These loose stones were discovered following a partial collapse of the Church of Santa Domingo during the 1930 earthquake. No examples have been found in original positions at these sites.

T grooves at Tiahuanaco are positioned on outer edges of flat surfaced building stones with the shaft of the T designed to match up with a corresponding T groove shaft on the next building block. When the two blocks are fitted together, the Ts line up and form and I or two Ts back to back. A pre-formed bronze insert in the form of an I or `Dog bone' was wedged/pounded into the groove giving the impression of a clamp or staple connecting the two stones.

What immediately comes to mind is why would the builders use or need a weak, small metal clamp to hold large stone blocks in place? One T grooved block at Ollantaytambo measures more than 10‘ feet in length with a thickness of 5 feet. The finest Inca masonry consists of carefully fitted, tapered and beveled blocks which have stayed in place through centuries of earth quakes.

The three sites mentioned represent important ceremonial construction. The Coricancha was the central temple of Cusco, the origin point of the ceques, sighting lines radiating out like spokes of a wheel from the hub of a cosmic observatory for tracking and coordinating celestial phenomenon with earthly events.

The temple site at Ollantaytambo, an enigmatic collection of finely made massive worked blocks of rhyolite from an earlier construction, appears to have been hastily re-fitted together at a later period. The T grooves, some 5 inches in length, curiously show evidence of having been polished. They are found only in several of the larger loose blocks near the hill top temple. None are found in original placement. The evidence of their original use is inconclusive. Jean-Pierre Protzen who has made an extensive investigation of the site believes that the groves represent an earlier construction idea that was later abandoned for different methods. (Protzen, Inca Architecture and Construction at Ollantaytambo, Oxford, 1993)


The third site, Nusta Espana is the Yuroc Rumi or white rock shrine made famous by Machu Picchu discoverer, Hiram Bingham in his search for Manco Inca’s Vilcabamba. A building-sized, sculptured, granite boulder dominates a small complex of ceremonial fountains, baths and the remains of several houses in a remarkable setting surrounded by high mountains.

In a recent visit, we found a large, loose granite building block with a T groove lying beside a ruined wall at one of the buildings. Perhaps further investigation will reveal its origin but the site is badly disturbed. Spanish raiders looted and destroyed Nusta Espana and it has suffered visits by huaqueros (tomb robbers) over the centuries.

It is likely that much of Inca architecture may have been decorative and stylized as well as functional. Some features incorporated in monumental architecture such as the double door jam, are found at Tiahuanaco and originated from earlier tradition.

Based upon these observations, I believe that the T grooves were decorative/symbolic rather than functional. They seem to be limited to important ceremonial constructions. Their practical use as a fastener in Inca construction is doubtful. Other non-functional architectural features were adapted from earlier tradition.

It is significant that no metal clamps/staples have been found at Inca sites. I believe it likely that the clamps, if they had existed at all, were made of Gold or silver instead of bronze as at Tiahuanaco. This would explain why none have been found as looters would have removed them. Of course, it is possible that the grooves themselves were a symbol or design and may never have contained metal inserts. The polished grooves found at Ollantaytambo would support this.

If they had no functional use and were only incorporated at the most important sacred sites it would fit with historical evidence. When the advance element of Pizzaro’s force arrived in Cusco in 1532, they described the Corichancha as “being bedecked with plates of gold and silver. “It seems likely that T grooves would have been fitted with gold or silver as well. They probably represented something more to their designers than mere decor. What that might be is now pure speculation,