This bears on the question of the origin of the rock out of which the monoliths are carved. The point has always been raised, how such enormous blocks could have been placed there. It was suggested that, many of them being andesite, the nearest point whence they could have been obtained was the peninsula of Copa cavana. It has been overlooked, that a number of the carved blocks are of the permian sandstone cropping out at Tiahuanaco. This is not the case with the material of the great doorway and other large and small pieces, but the tallest column and many other sculptured pieces are of the reddish sandstone underlying the soil. Mr. Sundt, who is quite an authority on Bolivian geology and lithology, has suggested that the andesite blocks of Tiahuanaco are erratic. 7 This does away with part of the mystery. The existence of similar sculptures in other regions contiguous to the lake (as at Kalaki on the peninsula of Huata) and elsewhere on that same pen insula, was ignored or overlooked.