In the early Jurassic period (180 Ma), a narrow ocean began to form between the northern (North America and Eurasia) and southern (Africa and South America) parts of Pangaea. The oceanic crust that was formed in the process is known as the Piemont-Liguria Ocean. This ocean is generally regarded as an western extension of the Tethys Ocean. Although it was not really connected to it, a peninsular piece of continental crust of the African plate called the Adriatic plate lay in between the African and European plates and was involved in subdividing the Tethys and early Alps formation. Sometimes the names "Alpine Tethys" or "Western Tethys Ocean" are used to describe a number of small oceanic basins that formed southwest of the European plate, to distinguish them from the Neo-Tethys Ocean in the east. Because the Jurassic was a time with high sealevels, all these oceans were connected by shallow seas. On the continents, shallow sea deposits (limestones) were formed during the entire Mesozoic.