This large open depression is a karst structure that, due to its geomorphological characteristics, simultaneously  represents  a ship (polje) and a ponor, commonly known as “olhos-de-água” or resurgence. Thus, it presents an open polje inside, with contours that are sometimes poorly defined, in an advanced state of evolution, and with evident structural control and the presence of several faults, especially in the reliefs that delimit it to the south (slope of Monte das Assumadas). The role of erosion is greatly evidenced by the shaping of the deposits of materials that fill the entire bottom of the depression with marine and fluvial facies.The ponor is found on the southern edge of the depression.