New GIS and iterated phase model of the Saalian glaciation in the Netherlands and NW-Germany

Some 170,000-150,000 years ago (during MIS 6), large ice masses last covered the Netherlands and NW Germany (Saalian Drenthe Substage). This left many geomorphological features in the landscape. Throughout
the 20th century extensive research has revealed the geomorphological assemblage of ice-pushed ridges, sandurs and glacial basins and dissective ice-marginal and deglacation river systems. From the assemblage,
sequences of glacial events, known as glaciation phase models have been constructed. The successive competing phase models of the 1960ies to the 1990ies each appear biased to specific features, subregions and types-ofdata.
New data exists and additional insights have risen since these former phase models became established. In this research the sequence of events was newly reconstructed, aiming to unify the evidence in NW Germany
with that in the Netherlands. In a GIS of dedicated design, we collected geological-geomorphological evidence from literature and (re)mapped features using new high-resolution elevation data. Importantly, we include
subglacial, ice-marginal, proglacial-drainage and deglaciation drainage features. The GIS was used to store and review existing phase models, and to iterate to an updated phase model across in the entire 300200 sq. km
of study area. Many elements of 'classic' phase models are retained and expanded, but inconsistent elements are dropped and new lines of explanatory reasoning replace them. We now recognise 3 phases towards
maximum ice-sheet extent (Drenthe advance), 1 tipping-point phase (Hondsrug ice stream) and 2 deglaciation phases (ending at the Warthe readvance). Improved structuring of observational data and, through GISdesign,
forcing oneself to produce continuous maps without gaps for each successive phase, greatly facilitates the construction of self-consistent phase models. The GIS and new-iterated phase model provides valuable input to subregional studies on past ice/bed interaction and present geohydrology.