Early Pleistocene Tiglian sites in the Netherlands: A revised view on the significance for quaternary stratigraphy

The Tiglian-A, B and C form the main subdivision of the Early Pleistocene Tiglian Stage in Northwest European chronostratigraphy since the 1960's. We re-evaluated the sedimentary context and new and legacy pollen assemblages of the classic type localities of these Tiglian pollen zones in the Dutch-German border area and Roer-Valley-Graben. Following recalculation of new upland pollen sums, we found that the three-fold subdivision of the Tiglian Stage is too simplistic and lacks a sound stratigraphic basis. The Tiglian-A is only found locally and cannot be positively identified in the RVG. The Tiglian-B in the Tegelen-Maalbeek area is not unique since similar occurrences are present at other depths in the RVG. Sedimentary and pollen analysis suggests Tiglian-C as defined in the Tegelen-Maalbeek type area could have been deposited in a very short amount of time, although this does contradict mammal data. The T-B/C cycle preserved in the type area likely represent a single example of multiple similar Early Pleistocene climate cycles. The sediments of the so-called cool or cold phase of pollen zone T-C 4^c in the stratotype of the Tiglian C substage are interpreted as having formed during the onset of crevassing and therefore its significance as a regional climate indicator is discussed. We conclude that the extrapolation of the Tiglian pollen zones into chronostratigraphical substages is questioned and it is concluded that the chronostratigraphical subdivision of the Early Pleistocene, based on palynological characteristics and palaeobotanical analyses, requires reconsideration based on independent dating and land-sea record integration.