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Figure 13.10. The probable sequence of periglacial slope evolution at Clatford Bottom, Wiltshire,
central southern England. From Small et al. (1970). Reproduced by permission of The Geologists'
Association.
sediment loads. At the same time, discharge fl uctuated in accordance with both diurnal
and seasonal melt of the ice sheets. Such conditions favor sediment deposition and braided-
channel aggradation.
An example of the complex interaction between slope and fl uvial processes is provided
by a study of slope evolution at Walewice, in central Poland (Dylik, 1969a, b). It demon-
strates how mass-wasting processes operated in conjunction with fl uvial sediment aggrada-
tion and fl uvio-thermal erosion to degrade, modify, and obliterate an earlier slope form.
Aspects of thermokarst, slopewash, and fl uvio-thermal erosion in current cold climates
have been described, respectively, in Chapters 8, 9, and 10. Over a period of several
summers during the mid-1960s, a series of trenches were systematically excavated along
a gentle slope extending away from the northern edge of a low terrace towards the center
of the Warsaw-Berlin pradolina, one of the major ice-marginal meltwater channels of the
central North European Plain (Figure 13.11). A synthesis of the results of the excavations
is shown in Figure 13.12.
The terrace is mantled with till (boulder clay) derived from the Middle Polish (Riss)
glaciation. Therefore, modifi cation of the terrace edge took place during the last (Wurm)
cold phase when the pradolina was functioning normally as a meltwater channel. The slope
that extends below the terrace consists of rhythmically-bedded silt and sand that has buried
three older, and steeper, slopes. Ice-wedge pseudomorphs, present in the stratifi ed sedi-
ments, indicate that deposition occurred under permafrost conditions. Lower down the
slope, the stratifi ed sediments are truncated by the second, completely buried, slope. At
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