The Alentejo region of Portugal is known for a high concentration of Neolithic-aged megalithic monuments: tombs (dolmens or antas) and ceremonial features such as standing stones (menhirs) and stone circles (cromleques). Concentrations of these monuments tend to be found on or near weathered granite terrains. Unloading slabs and remnant corestones appear to be the stones of preference for megalith makers in the Alentejo district of Portugal. Some of the stones may have been imported from distant sources, but most appear to be of local origin. In general, most stones do not appear to have been altered much from their original state as field stones. Weathering tests demonstrate that menhirs are essentially identical to native cornerstones. Many menhirs still exhibit a soil line. The former subaerial side of the stone usually retains a thick growth of lichen, while the soil side remains oxidized. Newly exposed, antas and menhirs now suffer from enhanced weathering and erosion from atmospheric and biological agents. This deterioration is often difficult to discern from the inherited decomposition of pre-megalithic time.
MSU Digital Commons Citation
Pope, Gregory A. and Miranda, Vera C., "A Geomorphology of Megaliths: Neolithic Landscapes in the Alto Alentejo, Portugal" (1999). Department of Earth and Environmental Studies Faculty Scholarship and Creative Works. 48.
Pope, G. A., & Miranda, V. C. A geomorphology of megaliths: Neolithic landscapes in the Alto Alentejo, Portugal. Middle States Geographer, 32, 110-124.