Detail of a terrace wall at Tarahuasi, west of Cuzco, composed of stones fitted in
the polygonal style. Adriana von Hagen.Extensive experiments have demonstrated that the process is effective and
precise, and not as time consuming as one might assume. Twenty quarry workers
laboring side by side could rough out a block 4.5 meters long, 3.2 meters wide,
and 1.7 meters high—the dimensions of one of the largest building blocks in the
ancient Inca quarry of Kachiqhata—in fewer than 15 days. Smaller blocks, like
those at Rumicollca, can be shaped in about two hours.
The most intriguing question about Inca cut stonemasonry concerns the
precision fitting of the blocks. It has been repeatedly argued that Inca
stonemasons ground the blocks into place using a mixture of sand and water. The
evidence, however, does not support this hypothesis. Where walls have been
dismantled or fallen apart one finds the exact imprint of the stones that have
been removed or fallen off. The shape of an imprint determines a unique position
for the stone that it once accommodated. To grind in a stone, however, requires
that the stone can move freely along a path in at least one direction. Thus, the
ground stone would fit in any, and not just one, position along that path.
Furthermore, if the stones had been ground into place, the joints should show
signs of abrasion, but they do not. Instead one finds the typical pit-marks, which
result from pounding.