ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

examples described in the literature for other high latitude
and high altitude environments. However, many of the channelized
·flows are also affected by slushflow activity which
has modified the sedimentological and morphological characteristics
of parts of their tracks. Between 1991-1996, only
one new deposit formed: a hillslope debris flow took place
in July 1993 after two days of precipitation totalling 30 mm
with a maximum intensity of about 8 mm in 12 hours.These
values fall well below the threshold usually required to initiate
debris flow, even in a permafrost environment.
Flow deposits were dated using a combination of photo interpretation
and lichenometry. Lichen growth curves for
the area were produced by correlating the sizes of Rhizo-
'carpon geographicum and Sporastasia testudinea specimens
with enlargement of ice-wedge polygon troughs.Geornorphic
work by rapid mass movements was relatively
uniform throughout the 20 th century with average vertical
transport estimated to be 17 x 10 3 Mgrn yr' km" (± half
an order of magnitude), corresponding to a rock denudation
rate of 0.05 mm yr" for the basins and peaks feeding
the east-facing slopes.Channelized debris flow produced
more than 700/0 of this transport. The maximum recurrence
interval for large channelized debris flows was 30 years,
substantially shorter than that reported from locations in
northern Scandinavia and Spitzbergen.This suggests that
weathering rates in the Sawtooth Range are relatively high,
probably because of frost-susceptible bedrock and frequent
freeze-thaw cycling.
To extend the record of rapid mass movement, six sediment
cores ranging in length from 1.0-2.2 m were retrieved
from a 2.9 km 2 lake (depth 140 m) that bisects the Sawtooth
Range adjacent to the terrestrial study area.The sedi ..
ment in the cores was predominantly non-laminated silt
with low organic content and it accumulated at rates of
0.13-0.22 mm yr' during the Holocene. Distinct coarsegrained
facies within this homogeneous material are, indicative
of rapid mass movements on the surrounding slopes.
Unlike results from mountainous areas of Europe and elsewhere,
the cores did not reveal simultaneous changes in
mass movement activity rates around the lake basin as
would be expected if regional climate change was a significant
factor. This indicates that rapid mass movements in
these cold, arid mountains are governed by processes acting
at the local slope scale, and that periods of enhanced
activity are controlled by a combination of intrinsic geomorphic
thresholds and micro-climate.
FENGHUA LI & FUTAO LID
On urban landform system structure of Changchun City
and its formation, planning and construction
Changchun Institute of Geography, Academic Sinica,
16 Gongnong Rd. 130021, Changchun, China
Urban geomorphology is an independent borderline
science between the geomorphology and urban sciences.
Urban landform system structure is closely related to the
urban formation, planning and distribution, precautions
of urban geomorphological disasters and the formation of
urban landscape, In this paper, we take Changchun city as
an example in order to analysize the basic feature of urban
landform system structure. Changchun is located in the
transitional zone between the eastern mountains and the
Northeastern Plain. According to the differences of
landform system structure, Changchun city can be divided
into six landform regions: Changchun platform, Xinlongshan
platform, Yitonghe River valley, Xinkaihe valley,
Jingyuetan hills and Xinlicheng reservoir. The city is properly
constructed in the eastern part of the Changchun
platform and in the central part of Yitongheriver valley.
The surface of the platform is of wave-shaped and the slope
is of appropriate. As it is made up of loess, it has a high
bearing capacity. On the platform, there are many shallow
valleys, which not only make drainage easy but also complicate
the urban landscape and make a good condition
for the proper construction of city and landscape distribution,
The forming history of Changchun city has passed several
stages. Russian and Japanese colonists had fighted for and
occupied this place early and later. They always choosed
landform parts favorable for themselves, consequently
being lack of general distribution, Changchun cityhas five
blocks differently arranged. This brings some difficulties
for later construction. "
The downtown of Changchun City is on the eastern' part of
Changchun platform. Industry zone and depository zone
were located outside the city according to the request of
their land utilization and landform conditions. The valley
is used as green land, the platform arid valley suburbs are
used as the production base of vegetable, side-food and
agriculture and husbandry. jmyuetan hills is a scenery zone
in suburbs, it also Can be used to develop fruit forestry.
Xinlicheng reservoir is a Water source of the city and can
prevent flood, in the mean time, it can be used to develop
fishery and forestry.
Changchun is well known as a forest and garden city, its
greenland area rate is the highest in the whole country. We
must make full use of the superiority of the landform systern
structure, keep and develop such a city scenery so
that keep it harmony with modern development.
JIANSHENG LI
Major artificial geological calamities in Hainan, China
Department of Geography, South China Normal University,
Guangzhou, China
Hainan Island is situated N 18° 10'-20° 10', E 108° 37'­
111° 03'; 180 km from southeast to northwest, 250 km
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