The geology around Visoko is incredibly rich, and I suggested to Osmanagic that, in lieu of “pyramids,” he might redefine his “Archaeological Park” as a “Geological-Archaeological Park” and focus more on the geology. Visocica Hill (the one dubbed “Pyramid of the Sun”) and Pljesevica Hill (“Pyramid of the Moon”) are composed of layers of sandstone, clay, mudstone, siltstone, and conglomerates apparently deposited in an ancient lake and river system during Miocene times (about 5.3 to 23 million years ago). The rocks have been tilted and bent due to tectonic stresses (this can be seen in the last photo to the right, which shows a natural folding and faulting in the rocks composing the side of a so-called pyramid in Visoko). The tectonic forces plastically deformed the clays and mudstones, but the sandstones and conglomerates broke into semi-regularly shaped pieces that Osmanagic and his team have excavated in numerous places, interpreting them as “pavements,” “terraces,” “concrete blocks,” “foundation stones,” and so forth. Interestingly, and tellingly, the sizes of the sandstone and conglomerate blocks found are a function of the thickness of the original rock layers. Thin sandstone layers, stressed tectonically, broke into small blocks while thick and durable conglomerate layers broke into massive blocks. This is exactly the pattern expected among natural rock formations. The sandstones also typically preserve various sedimentary and depositional features, such as ripple marks and the traces of ancient burrowing animals. These same rocks are also rich in paleontology. In some of the sandstone layers, and in many of the mudstone layers, I found large accumulations of fossil leaf debris and even some fairly complete Miocene fossil leaves. I believe that the real treasure of Visoko may be a huge fossil biota just waiting to be uncovered, not some imaginary pyramids.
