ABSTRACTS / RESUMES - Comitato Glaciologico Italiano

press) show that, during the Holocene, travertine has been
deposited by spring waters fed by limestone aquifers. The
production of travertine generally started in the Early Holocene
and ended (or underwent a strong decline) after
4,000 yr. B.P.
A satisfactory explanation of that is not yet available though
different hypotheses have been proposed by several
authors (see Goudie & alii, 1993): some of them point out
the influence of climatic changes, while others invoke the
effects of human impact. However, no specific reference
has been made to a possible role of spring water temperature
changes, notwithstanding their well known influence
on calcium. carbonate dissolution equilibria. In particular,
differences between lower temperature of ground waters
(influenced by deep penetration into the limestone bedrock
of Late Pleistocene surficial temperatures) and higher
external temperature at the spring may have played
an important role.
The infiltrating waters, enriched in CO 2 by percolating through
the new formed soils, acquired higher CaC0 3 dissolution
capacity because of underground temperatures colder
by several °C. The higher temperatures at the emergence,
in connection with algal-bacterial activity, may have
caused loss of CO 2 and travertine deposition.
This process may have continued for a long time because
of the low thermal capacity of limestone, the ground
water circulation through a wide network of fissures
within large volumes of dry rock, and the progressive
'increase of athmosphere temperature during Lower-MiddIe
Holocene.
KEVIN G. DRISCOLL & ]OSELITO M. AROCENA
Classification and genesis of selected pedons
in the Central Interior of British Columbia, Canada
Facuity of Natural Resources and Environmental Studies,
University of Northern British Columbia, 3333 University Way,
Prince George, British Columbia, Canada, V2M 2R3
Fifteen selected pedons were sampled from the very wet,
cool Sub-boreal Spruce biogeoclimatic zonein the central
interior of British Columbia, Canada. The study area, which
was deglaciated ca. 10,000 BP, is located west of the
Rocky Mountains. The surficial materials are sediments
and till laid down at the close of the Fraser Glaciation.
Glacial fluvial, glacial lacustrine and colluvial processes
were the predominant forces involved in laying out the parent
material for the current soils. The primary sources of
this material were the Rocky and Mackenzie Mountains to
the east and north of our study sites. Elevations range from
820 to 1070 metres above sea level with slopes between
5 % and 63 0/0. Mean annual soil temperatures range
between 1.2° and 2.5°C. Over 960 mm of precipitation falls
annually, including over 328 em of snow with levels increasing
with altitude. The vegetation of this region is dominated
by hybrid white spruce (Picea engelmannii x glauca)
with lesser amounts of subalpine fir (Abies lasiocarpai
and an understorey of devil's club (Oplopanax borridusi,
thimbleberry (Rubus paruiflorus), huckleberry (Vaccinium
spp.i, fireweed (Epilobium angustifolium) as well as other
herbaceous shrubs and grasses.
Six of the pedons were classified as Eluviated Dystric Brunisols
(Typic Cryochrept and Typic Haplocryod), one pedon
as a Gleyed Eluviated Dystric Brunisol (Typic Cryaquod),
five as Orthic Humo-Ferric Podzols (Typic Haplocryod),
two as Orthic Gray Luvisols (Typic Cryoboralf),
and one as Rego Humic Gleysol (Oxyaquic Cryoboroll).
Sodium pyrophosphate extractable Fe (Fe.) and Al (Alp)
was noted in one of the Luvisols, however, the eluviation
of clay (A horizon =5 % clay and B horizon = 12.4 % clay)
superseded the podzolic soil (Btl horizon: (Fep+Alp) =
0.890/0; Bt2 horizon: (Fep+Alp) = 1.1 %) in the Canadian
System of Soil Classification. The Eluviated Dystric Brunisols
showed signs of Fe and Al movement, though not
enough to satisfy the requirements of Orthic Humo-Ferric
Podzols. Levels of Fe., for the Brunisols ranged between
0.12-0.360/0 and the podzolic B horizons in the Orthic Humo-Ferric
Podzols were 0.41-0.630/0. The (Fep+Alp) levels
were 0.30-0.47 % for the Brunisols compared with 0.54­
0.95% for the Podzols. Similarly, the (Fep+Alp)/clay levels
in the Brunisols ranged from 0.014-0.24 % compared with
0.072-0.360/0 in the Podzols. The Luvisols seemed to have
formed from different parent compared to the Brunisols
and Podzols. With the exception of the Rego Humic Gleysol,
all the pedons were believed to be zonal soils.
Incipient podzolization seems to be the dominant pedogenic
process in the area. The sandy parent materials, cool
temperatures and high precipitation rates provide a mechanism
conducive to the translocation of organic acids
with or without Fe and Al into the B horizon. With time, it
is anticipated that the Eluviated Dystric Brunisols will develop
into Orthic Humo-Ferric Podzols. The Gleyed Eluviated
Dystric Brunisol will probably develop into a Luvisol
as it has been formed on different parent material and
showed some degree of clay eluviation.
Lessivage is also an active process within the region. Increases
in clay content with depth for the two Luvisols ranged
from 5-7.90/0 in the Ae horizons to 12.6-13.4% in the
Bt, Four of the Brunisols (A horizons ranged from 4.8­
15.20/0, B horizons ranged from 5.4-16.4%) and two of the
Podzols (A horizons ranged from 2.8-9.2%, B horizons
ranged from 5.2-9.6 0/0) showed lower increases in clay
content from the A to B horizons.
Gleyed features in pedons resulted from changes in microtopography.
The Rego Humic Gleysol was formed on colluvium
at the base of a relict avalanche which explained
the poor drainage and high level of organic matter found
in this pedon, Water seepage was found within a sand
layer at a depth of 59 em in the Gleyed Eluviated Dystric
Brunisol.
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