摘要：Abstract
Comprehensive chronological, geological and
paleontological investigations were conducted as part of
archaeological excavations in 2011 and 2012, prior to the
construction of the M85 motorway between Gyor and
Csorna, Hungary. These studies clearly show that the alluvial
fan that underlies much of the Little Hungarian Plain
was built up by streams flowing in a southeasterly to northwesterly
direction from the nearby Bakony Hills, and continued
to form until the end of the last glacial period. The
northern part of the fan, now named the Csorna Plain,
became inactive (i.e. became a fossil river-bed system) at
about 25–15 ka, when the Rába and Marcal rivers changed
theirflowdirection fromsouth–north towest–east.As a result
of this change in flow direction, the Rába and Marcal
rivers became incised, capturing the Bakony stream beds,
stopping sediment deposition on the northern side of the
alluvial fan (essentially the left bank of the Rába-Marcal
river system), although the southern part of the fan continue
to form as before. On the northern side of the fan, the
sediment surface dried out due to falling groundwater levels,
and aeolian sand-drifts began to form. Eventually, accumulation
of the sand-drift sediments ceased due to the
deposition of loess-type sediments, which fixed the surface,
conserved the sand-drift shapes, and contributed to
the straightening and eventual canalization of the fluvial
channels. Geoarchaeological examinations indicate that
the development of present fluvial features were strongly
affected by the settlement and tillage activity of human
communities on the Csorna Plain.
关键词：KeywordsLittle Hungarian Plain river capture Csorna
Plain fossil river-bed
