Detecting upland glaciation in Earth’s pre-Pleistocene record

Earth has sustained continental glaciation several times in its past. Because glaciers ground to low elevations, sedimentary records of ice contact can be preserved from regions that were below base level, or subject subsidence. In such regions, glaciated pavements, ice-contact deposits as glacial till with striated clasts, and glaciolacustrine glaciomarine strata dropstones reveal clear signs former glaciation. But assessing upland (mountain) poses particular challenges because elevated typically erode, thus have extraordinarily poor preservation potential. Here we propose approaches for detecting the presence absence near-absence indicators; apply this specifically problem glaciation, consider implications Earth’s climate system. Where even piedmont are eroded, pro- periglacial phenomena will constitute primary record Striations on large (pebble larger) clasts survive only a few km fluvial transport, but microtextures developed quartz sand longer distances high-stress fractures consistent Proglacial systems difficult distinguish non-glacial systems, preponderance facies signaling abundant water sediment, hyperconcentrated flood flows, non-cohesive fine-grained debris and/or large-scale coarse-grained cross-stratification proglacial conditions, especially combination evidence cold temperatures, rip-up composed noncohesive indicating frozen predominance physical over chemical weathering. Other indicators freezing (periglacial) conditions include frozen-ground fossil wedges crystals. Voluminous loess eolian-marine silt/mudstone characterized by silt modes, significant proportion silicate minerals, provenance non-silt precursors indicate operation grinding, though may far removed site(s) Ultimately, unambiguous indicators, inferences must grounded an array observations together meltwater, temperatures capable sustaining weathering (e.g., grinding). If arguments viable, they bolster accuracy past models, guide modelers types forcings could enable at elevation, well extent which (extensive) might influenced global climate.