Based on stratigraphic position, lithostratigraphic correlation, palynological analyses, and other means of geological dating, the Ecca Group ranges between Early to earliest Middle Permian (Asselian - Roadian) in age.
The Ecca sea was vast but shallow, reaching only around 500 m at its deepest in its west/northwestern and southern facies where the Tanqua and Laingsburg Depocenters are situated respectively.
The mountain-building and erosion caused by the growing Gondwanide mountain range was the initial subsidence mechanism acting on the Karoo Basin.
[7][8][9][10][11] The rocks of the Ecca Group first appear near Sutherland in its westernmost deposits, and continues east through Laingsburg, Prince Albert, Jansenville, Grahamstown, and up until the coast near Port Alfred.
In the extreme northeast deposits are found east of Johannesburg past Vryheid, Durban, Pietermaritzburg and all the way down to Port St. Johns in the southeast.
Near the small town of Khorixas in Namibia there is a locally well-known national monument called the Petrified Forest.