Forward modelling of the completeness and preservation of Quaternary palaeoclimate signals recorded by ice-marginal moraines

Glaciers and ice sheets fluctuate in response to climatic change and often record these changes by building ice-marginal (terminal and lateral) moraines. Therefore, glacial landscapes are a potentially valuable archive of terrestrial palaeoclimate change. Typically, a cooling climate causes glaciers to expand and warming causes glaciers to shrink. However, the influence of high-relief mountainous topography on glacier dynamics complicates this behaviour, such that ice-marginal moraines are not always a straightforward palaeoclimate indicator. We used a higher-order ice-flow model to simulate change in glacier erosion, extent, and thickness in the response to climatic change and the resulting formation and preservation of moraines in a synthetic mountain landscape. Our results show that the rate of palaeoclimatic change relative to the glacier’s response time determines the geometry, number and position of ice-marginal moraines. However, glaciers can build distinct moraines in the absence of climate change, and the distance from the glacial maximum may not represent the chronological order of moraine formation. While moraines can be preserved despite erosion during subsequent glaciations, moraine sequences frequently contain gaps that could be misinterpreted as representing more stable palaeoclimates. These results provide theoretical understanding for the interpretation of glacial landforms both in the field and from satellite data (e.g. digital terrain models) to understand Quaternary climate change.