People say they look like the corn bread's crust
The Pedras Boroas of Junqueiro are located in one of the granite residual relieves of the Freita mountain’s plateau. In this geosite, it is important to refer the existence of two granite blocks, one of them moved from its original position, and both present a clearly visible polygonal cracking. The polygonal cracks are clearly individualized and extend through the entire vertical surface of these blocks. They generally present 5 to 6 non regular sides and just a few centimeters deep.
According to the students of geomorphology, the genesis and evolution of these geoforms involves the association of sub-superficial and subaerial processes. This type of shape started sub-superficially and with a straight relation with the structure of the rock, as we can see in the clearly defined cracks, developed in vertical fractures, of this residual relief, thus highlighting the relevance of this geosite. This fractures/cracks network allows the water circulation, providing the occurrence of physico-chemical processes and the progression of the weathering and erosion, that has continuity with the subaerial exposure of the blocks.