The harbour had two large basins, now almost choked with sand.
The basins of the Parana and Paraguay are separated by low mountain ranges extending north from the sierras of Paraguay.
The dockyard, chiefly used for naval repairs, covers about 60 acres, and consists of three basins and large docks, the depth of water in the basins ranging down to 26 ft.
Towards the end of the period, however, during the deposition of the Portlandian beds, the sea again retreated, and in the early part of the Cretaceous period was limited (in France) to the catchment basins of the Sane and Rhnein the Paris basin the contemporaneous deposits were chiefly estuarine and were confined to the northern and eastern rim.
These saline basins extend down to the lower terraces of Cordoba, Mendoza and La Pampa.