Geomorphology of the Canale di Pirro Karst Polje (Apulia, Southern Italy)

Canale di Pirro is one of the most remarkable karst features of the Murge, a typical district of the Apulian karst of southern Italy. It is a 12 km-long polje, with a further and less defined prolongation inland, until reaching an overall length of some 30 km. The floor is filled by thick terra rossa deposits, whilst the slopes are in Cretaceous limestone which represents the bedrock in the area. In the past centuries, this geomorphological feature attracted the attention of several travellers, and was often described as a huge lake, probably because of its characteristic to maintain water at the surface for several days after rainfall, due to the very low permeability of the bottom deposits. As regards caves, two types of natural caves characterize the polje: a prevailing vertical type in the polje floor (difficult to explore because of the infilling deposits that easily clog the access), and sub-horizontal caves in the form of shelters along the slopes. The polje floor develops at two different elevations, separated by an intervening geomorphological saddle: these elevations correspond to two important karst levels in the Murge, as testified by the development of important system of caves in the neighbouring territories. The combination of surface and subsurface geomorphological data provides a first contribution toward a better understanding of the karst history in the area. © 2006 Gebrüder Borntraeger.