The Dogger Group above Opalinus Clay spans most of the Middle Jurassic, from the Middle Aalenian to the Callovian and partly also to the earliest part of the Late Jurassic (Early Oxfordian). Within this interval, five timelines were picked (170.9_Aal_200 to 168.2_Baj_100; Fig. 4‑33). These timelines were picked based on the integration of detailed biostratigraphic, chemostrati­graphic and lithofacial (e.g. hardground) criteria (for data please refer to Dossiers III and IV of data reports of the TBO campaign, see Tab. 2‑1). The timelines generally follow lithostratigraphic boundaries, but partly cross or are within lithostratigraphic boundaries, reflecting lateral facies changes in time-equivalent periods (Fig. 4‑33).