Geology Reference
In-Depth Information
Plate 14.2
The site of Altis, excavated from the Younger Fill, looking towards Kronos Hill. The building on the near left
still contains the fill.
(
Photograph by Jamie Woodward
)
Karl Butzer (2005) favours an interpretation of the
fluvial history of Olympia based on extreme precipi-
tation events associated with intervals of high climatic
variability triggering or exacerbating a landscape already
destabilized by human activity. He contends that such
events lead to the erosion of susceptible slopes by sheet-
floods or gullying. The eroded material then forms
poorly sorted colluvium on concave footslopes, any
excess sediment being carried into streams during heavy
bouts of rain. A stable phase ensues if an abatement of
human activity allows vegetation to recover. However,
should human pressures resume, secondary episodes of
landscape disequilibrium would see renewed erosion, the
entrenchment of channels, and braided streams.
the lower Rhine at Wessel. The Lippe Valley contains
a floodplain and two Holocene terraces, the younger
being called the Aue or Auenterrasse and the older the
Inselterrasse. Both these sit within an older terrace - the
115,000-110,000-year-old Weichselian Lower Terrace
(Figure 14.5). The Inselterrasse ('island terrace') is a
local feature of the lower Lippe Valley west of Lünen.
It began to accumulate about 8,000 years ago and stopped
accumulating about
AD
980, and survived as separate ter-
race islands left by abandoned channels. The Aue (or
'towpath') runs from the headwaters, where it is quite
wide, to the lower valley, where it forms a narrow strip
paralleling the river channel. It is younger than the
Inselterrasse. The characteristics of the Holocene valley
bottom are not typical of valley bottoms elsewhere in cen-
tral Europe. The peculiarities include the confinement of
the Inselterrasse to the lower Lippe Valley, the separation
in places of the Inselterrasse into two levels that are not
always clearly distinguishable, the Aue's being just a nar-
row strip in the lower reaches, and the Aue's lying above
the average flood level while the Inselterrasse is peri-
odically flooded and in historical times was frequently
flooded.
Human impacts in the Lippe valley,
Germany
The Holocene history of the River Lippe shows how
human activities can materially alter a fluvial system
(Herget 1998). The Lippe starts as a karst spring at
the town of Bad Lippspringe and flows westwards to
