Sediments

Sediments found on the plateau are most likely to be allochtho-nous or autochthonous blockfields/felsenmeer/detritus, and have been interpreted as the product of long-term weathering (Weichselian to pre-Pleistocene). On plateaux, tills tend not to be formed, owing to the dynamics of the ice cover. In the valleys thin, generally patchy tills are found and proglacial reworking of sediments by large braided river networks may occur. Lake sediments

Figure 20.2 Equilibrium line altitude (ELA) shifts for the inclusion of contributing plateaux to coupled plateau-outlet-valley-glacier systems for (a) the Little Ice Age maximum in the southern Lyngen Peninsula, North Norway, and (b) the Younger Dryas reconstruction of 0ksfjordj0kelen, North Norway. Equilibrium line altitudes were calculated using the accumulation area ratio (AAR) method. Bars indicate the limits of the shift for AARs of 0.5 and 0.8.

Figure 20.2 Equilibrium line altitude (ELA) shifts for the inclusion of contributing plateaux to coupled plateau-outlet-valley-glacier systems for (a) the Little Ice Age maximum in the southern Lyngen Peninsula, North Norway, and (b) the Younger Dryas reconstruction of 0ksfjordj0kelen, North Norway. Equilibrium line altitudes were calculated using the accumulation area ratio (AAR) method. Bars indicate the limits of the shift for AARs of 0.5 and 0.8.

iers onto plateaux. In higher relief landscapes, where plateaux tend to be smaller/more dissected, steep valley-head outlets, direct calving of plateau edges and low melt volumes tend to preclude the cutting of lateral meltwater channels. Larger (lower) icefields tend to have outlets with basal ice at the PMP, producing subglacial meltwater and allowing surface meltwater to percolate to the bed. The subglacial bedrock topography and ice-surface slope act to channel the meltwater towards the outlets, forming channelized subglacial and ice-marginal meltwater streams. If the water drains directly off the plateau edge steep alluvial fans will form at the base of plateau edge gullies.

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