No abstract

New information from borings shows that in the region to the west and north of the Lons-le-Saunier basin, France, the Jura border is thrust over the Tertiary of the Bresse region. The age of the movement is post-Pontian, and the amplitude over five kilometers at certain points. The movement occurred along gypsum and salt zones in the lower Keuper and Muschelkalk (Triassic) without disturbing the underlying Triassic, Permian, and Carboniferous beds.

Defines the stratigraphic subdivisions of the Keuper (Triassic) series of the Jura region, France, on the basis of a study of numerous borings and extremely detailed mapping. Special attention is called to a dolomite, averaging 10 m thick, which is an important key zone in the upper Keuper, and to other diagnostic features.

Redescribes Orbitammina elliptica, a large foraminifer from upper Bathonian (Jurassic) deposits of Aisne and the Ardennes region, France, and discusses its relationships and affinities with members of the genera Orbitopsella and Spirocyclina. O. elliptica has previously been described also as a pelecypod and as a brachiopod. It is considered to represent a form intermediate between Orbitopsella and Spirocyclina.

SUMMARY Karst depressions are filled (or lined), at least in the first stages of their development, with material subsiding from permeable deposits that cover the carbonate rocks. Without such a cover no depressions can be formed. In the case of very impure limestones, the fill of the depressions consists for a great part of the insoluble residue from these limestones. Simultaneously with the morphological evolution of the depressions, their fillings also undergo important changes. The evolution terminates with a denuded karst. The solution processes may be re‐activated if the surface is covered by new (allochthonous) sedimentary material.