ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

«Pali» d'Hawaii et supposent un enracinement plus
profond, ou encore Ie basculement centripete de certaines
unites de la structure. Une interaction des effets de la tectonique
regionale et des processus lies au volcanisme parait
inevitable. Les failles impliquees dans Ie glissement se situent
d' ailleurs generalernent sur des directions regionales.
Les consequences du glissement se sont ajoutees aun phenomene
plus large de bombement et de baseulement du
N-NO vers Ie S-SE du substratum de 1'Etna.
Cette interaction a joue un role dans Ie decoupage du versant
oriental par les «Timpe», mais aussi dans la vigueur
des mouvements pendant les periodes d' activite de l'Etna.
Cette vigueur est illustree, sur la bordure littorale, par l'etagement
de plusieurs niveaux marins et un soulevernent
qui a localement atteint plusieurs metres a l' epoque historique.
JONG-WOOK KIM
Studies of the functional fluvial geomorphology
in Young-Dong, Korea
Department of Geography Education, Seoul National University,
Kwanak-Gu, Shillim-Dong, 151-742, Seoul, Korea
The aim of this study is to analyze the fluvial morphological
characteristics of streams of Young-Dong area in Korea
especially in terms of functional geomorphology. These
streams originate on the east slope of Tae Back Mountain
(the backbone mountain of Korea Peninsular), which was
uplifted during Miocene, and flow into the East Sea.
Three of those streams were chosen for this research :
Shilli, Sachun, Gunsun. The bedrock of the drainage basin
of Shilli and Sachun is relatively homogeneous, consisting
of granite and gneiss, but the one of Gunsun is more
complicated, consisting of granite and the various kinds of
Paleozoic sedimentary rocks. Compared to the streams on
the west slope of Tae Back, the length of these streams is
relatively short : Shilli 15.8 km, Sachun 18.6 km, and
Gunsun 18.5 km. And the drainage basin area is also relatively
small: Shilli 42.3 krn', Sachun 55.6 km 2 and Gunsun
68.9 km',
Currently these streams are arousing special interest in
terms of functional geomorphology. This is because they
are considered to have some remarkable features which
can be traced to streams which flow relatively rapidly
down from higher elevations, contrary to streams on the
west slope of Tae Back. To facilitate of this study, some
components of the drainage basin system, the valley system,
and the stream channel system were surveyed using
field work and map analysis. Especially, the characteristics
of the hydraulic geometry of streams were more intensively
researched. The principal results are as follows:
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1. The morphological characteristics of the drainage basin
and the channel network changed remarkably depending
upon the lithology of the bedrock. Streams, Shilli and Sachun,
which flow on the same bedrock, granite and gneiss,
show almost the same characteristics especially in terms of
the shape and relief of the drainage basin, valley shape,
drainage network pattern, etc.
2. The hydraulic geometry and bed materials of the
streams on granite and gneiss, Shilli and Sachun, show similar
characteristics, contrary to streams on sedimentary
rock, Gunsun. So, it might be reasonable to conclude that
the lithological condition strongly influences the fluvial
morphology in the study area.
3. The functional fluvial morphology is quite different
between the upper reaches of streams and the lower reaches.
The upper reaches show characteristics similar to
those of mountains, but the lower reaches resemble more
alluvial channels. Also, the change in stream characteristics
from the upper reaches to the lower reaches is relatively rapid.
This might be caused by the uplift of the Tae Back
Mountain and the changein the sea level.
OWEN G. KIMBER, ROBERT J. ALLISON, & NICHOLAS J. COX
Rates and mechanisms of change in hard rock steep
slopes on the Colorado Plateau, USA
Department of Geography, University of Durham,
Durham, DR1 3LE, UK
The development of steep slopes in hard jointed rock has
been studied on the Colorado Plateau, USA. Advances
made in other scientific disciplines have meant that the
material properties of a rock mass are well understood and
have been combined with geomorphological information
in a distinct element computer program to develop models
of cliff evolution. It is demonstrated in a theoretical study
how the material properties in a rock mass, particularly the
geometry of the discontinuities, affect the mechanisms of
slope failure and therefore the development of steep slopes.
Results of the modelling completed using geotechnical
data from the Canyonlands, Utah district of the Colorado
Plateau, establish the approach in the understanding of
hard rock slope development. High, vertical cliffs of horizontally
bedded Jurassic sandstone are topped by a jointed
cap rock to form mesas and buttes in this region of spectacular
rock landforms. While discontinuity orientation remains
relatively constant spatially, spacing between sets varies,
leading to differences in cliff development. Where the
discontinuity spacing is greatest, buttes have become detached
from the main cliff. The modelling demonstrates how
the distinct element technique can be used to elucidate
landform evolution.