Upper Jurassic rocks are widespread in the surface outcrops of Tunisia and adjacent areas in Algeria and Libya. Deep drilling in central Tunisia during the past 15 years has revealed the presence of a thick rock sequence of limestone and calcareous shale which are recognized as Middle Jurassic (Callovian, Bathonian, and Bajocian), and which, in some places, are 1,500 meters thick.

To facilitate better understanding and appreciation of the geological framework and setting for the depositional trough which accommodated this thick series of sediments, maps showing the areas of Triassic outcrops and the thickness of these beds at the surface and in the subsurface are presented. The environment and nature of Triassic sediments are presented, followed by a discussion of the entire Jurassic System in Tunisia. Emphasis is placed on the Middle Jurassic and on the possible role of "Dogger" beds of early Middle Jurassic age serving as reservoir or source beds for oil and gas.

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