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Marine Lower Devonian successions are widely exposed in the Dra Valley (Southern Anti-Atlas, Moroccan Pre-Sahara). Resulting from new studies, especially on brachiopods, conodonts, and dacryoconarid tentaculitids, the chronostratigraphic assignments of the Lower Devonian formations are revised. Thanks to lateral and vertical facies variations, it is possible to correlate pelagic and neritic successions and corresponding biostratigraphies. Pelagic conodont, dacryoconarid and goniatite faunas allow correlations and dating in the sense of the Bohemian and global chronostratigraphies, whereas units of the traditional Rhenish subdivision can be identified by means of neritic brachiopods.

In the Eifel area (western Rheinisches Schiefergebirge), a shallow- to deep-subtidal sequence of mixed carbonates and siltstones around the Kačák Event Interval close to the Eifelian–Givetian stage boundary was studied. An overall transgressive trend is inferred by the microfacies evolution. The stratigraphic variations of magnetic susceptibility in carbonates and in shale intervals show an overall decreasing evolution towards the top, which fits well with the transgressive trend. In addition, carbon and oxygen isotopes, and major, trace and rare earth element (REE) analysis have been used to get a better understanding of palaeoenvironmental variations in a shallow-water realm in the late Eifelian (kockelianus and ensensis conodont biozones): for example, the δ13C excursion and Ce anomaly are interpreted to be the local representation of the beginning of the Kačák Event Interval, which is also consistent with the stratigraphy and microfacies analyses.

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