I acknowledge all the Christmases and birthdays I missed as a result of working in Antarctica and the burden this placed on Alida. I would like to thank Professor van Zinderen Bakker (University of the Orange Free State), who gave me my first opportunity to work in Antarctica and who continued to support me in recent years.
Introduction
Weathering
Weathering includes all the processes that cause the dissolution and alteration of rocks in the upper crust (Oilier, 1984). Recognition of this is important, for the mechanism of debris removal, even by such a straightforward process as gravity fall, is as intimate a part of the formation of this feature as is weathering.
Freeze-thaw Weathering
Thus it can be appreciated that freeze-thaw is a complex process with many questions still unanswered, but that its central theme is that of the freezing and thawing of water within the rock, the effects of which, in some way, cause weakening and weakening and the possible ultimate failure of that rock. Glacial eruption (called 'clarification' by Lautridou, 1985) was mathematically justified by Bertouille (1972) but has been little observed outside the study of Michaud et al.
What is a 'Cold Environment'?
According to Burdick, et al. 1978, p.1) a "more practical definition" of a cold environment can be based on design and operational requirements essential to the maintenance of the industrial and social economy. Similarly, Swanberg (1945) also monitored air temperatures at the top and bottom of a plate and at various depths up to 1.52 m (60 in) and calculated the number of freeze-thaw cycles that could roads and sidewalks are subject.
Cold Region Weathering Information from General Textbooks
34; Hydrofracturing and frost action are two of the most important and well-known physical weathering processes."
Weathering Information from Cold Region Texts
34;Rock Shattering: This is almost entirely the work of freeze-thaw; the role of other processes is negligible.”
A number of points emerge from the above
- Information from Antarctic Books
- Landforms Associated with Mechanical Weathering in Cold Regions
- Synonyms
- Discussion
- The Present Research Undertaking
- Conclusions
34;..what periglacial geomorphologists need more than any other single object is a way to determine in the field whether bedrock fragments have been frost-weathered or not." To date, no such test exists. Thus, given ".almost total ignorance of both field conditions and applicable theory, the experiments have not even ruled out the possibility of other mechanisms."
Field Data
The salt content lowers the freezing point, and salts can precipitate during drying of the rock or during the freezing process (to create a cryohydrate), thus facilitating the salt weathering of that rock. A block of stone that e.g. has only 25% saturation relative to the whole block, is likely to have 100% saturation in the outer shell due to the moisture gradient in the rock.
Thermal Data
2001 a. The necessity of high-frequency rock temperature data for rock weathering studies: Antarctic and northern examples. The conceptual fallacy of "weathering in cold climates" - the fallacy of the assumption of zonality.
Moisture Data
S.A Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire, 18
Rock Properties
A method for the extraction and analysis of dissolved substances from rock samples and their implication for weathering studies: an example from the maritime Antarctic.
Weathering Rates
From the perspective of weathering in cold regions, no data at all were available regarding interstitial rock water chemistry and almost none regarding rock moisture content. An attempt was therefore made to undertake monitoring of rock moisture content in the field, including its temporal and spatial variability, and to derive a method for determining rock moisture chemistry.
FREEZE-THAW ACTIVITY AT A NIVATION SITE IN NORTHERN NORWAY
HALL / 183
As part of a study of nivation processes in northern Norway (Hall, 1975), a detailed study of freeze-thaw activity and the mechanism involved was undertaken. These data were then used to estimate the freeze-thaw conditions operative within the nivation process and their variation throughout the year.
INDBRE
Extrapolation from the nearest meteorological station, Hattfjelldal (380 m a.s.l.) about 55 km to the south, suggests a mean annual temperature in Okstindan between -°2 and.
LAKE
HALL / 187
On the eastern edge of the snow, and on the western edge to a lesser extent. Freezing of the soil during the autumn to winter period clearly occurs from the surface down (Fig. 5). Water that enters the back of the snow from melting along the back wall is able to move under the snow cover.
PROCEEDINGS OF
PERMAFROST
OFFPRINT
New Data from Viking Valley, Alexander Island, Antarctica
It is argued that without data collection at two-minute or preferably one-minute intervals it is not possible to distinguish the weathering regime, including interpreting the freeze-thaw process. 34;freeze-thaw" (or one of its many synonyms) is cited as the dominant process, and in most cases it is the air temperature that is used as the basis for this premise. In any consideration of freeze-thaw weathering , moisture and rock properties are as important as thermal conditions (McGreevy and Whalley, 1982; Hall and Walton, 1992; Hall, 1993).
LEGEND
Mars Glacier
1 Unnamed Glacier 2 Bedrock
Considering summer first, details of the rock surface and air temperature values are given in Table I. The impact of the meltwater on the rocks is clearly shown by the ultrasonic data (Figure 4). Looking at the first part of the data (i.e. the summer to autumn section) both years clearly show frequent exceedances of O°C for the rock data, but considerably less so for the air.
Detail of temperatures in taffoni
Thus, salt weathering can be expected in the valley and potentially in the rest of the nunatak, as salt efflorescence has been observed there. Thus, a qualitative assessment of the role of freezing and thawing in this area (and comparable locations) is spurious and not supported by the data. There is also a distinct side effect on the nature of the thermal environment experienced by the rock.
FOURTH INTERNATIONAL CONFERENCE ON GEOMORPHOLOGY
QUATRIEME CONFERENCE INTERNATIONALE DE GEOMORPHOLOGIE
ABSTRACTS / RESUMES
The age of formation of the marine-erosion terrace is assumed to be the same as the weathering cime(t) for the bedrock below the kerace surface. during co they scarcelv eroded awav. The analysis of data on freezing events made it possible to determine the rate of temperature drop and thus to derive possible freezing and thawing mechanisms. Any deduction from the freezing process depends on the rate of temperature change.
Rock Temperatures and Implications for Cold Region Weathering
New Data from Rothera, Adelaide Island, Antarctica
In that paper, winter observations were detailed, which showed the thermal regime of the rocks for the first part of two consecutive winters, while detailed summer temperature data indicated the likelihood of thermal shock and thermal stress fatigue as important weathering processes. It has been argued that recording intervals of 30 seconds or one minute would be better not only for the identification of thermal shock but also for the assessment of freeze-thaw weathering for which the rate of temperature change is critical (McGreevy and Whalley, 1982; Hall , 1995). This paper presents data collected at one-minute intervals for the rock surface and at 2 cm depth on the four cardinal aspects, plus on a horizontal surface, for almost three weeks from a rock pile located over the airstrip at the British Antarctic Survey lookout. Rothera Base (Figure 1), Adelaide Island (67°34'S, 68°07'W).
Rothe a
Examples of the important loss of detail in records other than the one-minute recording interval are shown in Figure 4. Surface and 2 cm depth rock temperature data show that complex stress fields must occur in the outer shell1 of the rock. Here in the example shown, the rock at a depth of 2 cm remains warmer than the surface for most of the day.
1st European
Permafrost Conference
March 2001
Most available mountain temperature data are at a frequency that (a) is not suitable for inferring some processes, (b) produces a false "picture" of the weathering regime, and (c) becomes a self-fulfilling prophecy of the initial assumption due to insufficient data. It will also be shown that weathering regimes at high latitudes vary greatly both spatially and temporally, where e.g. the pole exposure is warmer and experiences fewer freezing events - than the equator exposure for part of the year. Finally, while contemporary discourse has moved from daily freeze–thaw events to the annual freeze–thaw cycle as being of the greatest geomorphic effect, recent data have shown that this may in part be an artifact of available data.
The pecessi for high frequency rock temperature
DetaibfExotherm andatlcmdepth
Detailofthesurfaceexotherm
Rateofcbaoeeoftemperature
2001 The DepartlDeDt 0
Thus, records of the location of the original network of trails used by the Tsleil-Waututh should be identifiable in the maps and journals of the early colonists. One of the most pressing environmental problems facing modern society today is the disposal of toxic, hazardous waste. This article reviews the results of recent research on specific aspects of the general process of change, namely: water scarcity, forest harvesting, and planning for population aging.
Rock fracture patterns There is physical evidence to
The same set of weathering processes is cited for hot deserts as for cold water limits in both, not temperature.
Thermal Gradients and Rock Weathering at Low Temperatures: Some Simulation Data
However, although many workers recognize the importance of the rate of temperature change on the rock, actual data are extremely rare (Table 1). In the outer shell of the rock there is a very steep temperature gradient (x = 7.5°C/cm for the outermost 3.3 cm). Regarding the second factor, the temperature data show (Figure 2) that the interior of the rock still experiences heating when reaching the outer part.
GlOMOHPHOlOGY
So if the negative features of the three discussion points above can be overcome, the impact of 6.T/t. Detail of temperature data for the four cardinal directions plus the horizontal surface for December 11, 1999. An important factor in thermal weathering processes must be the duration of the thermal stress.
ROCK MOISTURE CONTENT IN THE FIELD AND THE LABORATORY AND ITS RELATIONSHIP TO MECHANICAL
WEATHERING STUDIES
45°38'W), one of the smaller islands in the South Orkney group (Figure 1), as part of the Fellfield program (Walton and Hall, submitted). The majority of the samples (63'0 percent) have an S-value that correctly reflects the percentage of unused space and there is a reasonable correlation (r= -0-60) indicating this (where x= percentage of unused space eny= S-value ). The most important aspect of rock moisture that remains to be resolved is that of its distribution within the rock.
DAILY MONITORING OF A ROCK TABLET AT A MARITIME ANTARCTIC SITE: MOISTURE AND WEATHERING RESULTS
HALL
Only one tablet was used, but the results are considered to be typical of the quartz-mica schist that comprises much of the island. Details of the properties of the tablet left in the field at the start of the experiment (1983-4) are given in Table I, while the daily changes in mass are plotted along with the width. For most of the winter period, the tablet was covered with snow or ice, which further prevented access to water.
HALL
Wetting and drying is an inherent part of freeze-thaw, to the extent that the moisture state of the rock varies. Conversely, the schistose nature of the rock may facilitate hydrofracture in some cases (Powers, 1945; Walder and Hallet, 1985). However, it may well be that this is due to the 'cut' rather than 'natural' nature of the tablet.
Rock Moisture Data from the Juneau Icefield (Alaska) and Its Significance for Mechanical Weathering Studies
Temperature and rock mass measurements were taken every hour for one day for each rock sample. It may be that the heating of cold rock causes the transfer of water vapor due to the temperature gradient in the rock. The expansion and contraction of the slime algae, which live parallel to the surface of the rock but at a depth of a few millimeters, was a direct result of the wetting and drying.
Rock Moisture Data from Livingston Island (Maritime Antarctic) and Implications for Weathering Processes
Rock Moisture Data and Implications for Weather 247 South Shetland Islands and is one of the. At the site, 3 thermocouples were attached to the rock surface on each of the cardinal faces and also read when the rocks were weighed. For the cutting head, the size of the samples used corresponds to approx. the outermost 60 mm of the bedrock.
FROZEN GROUND WORKSHOP
OUR CURRENT UNDERSTANDING OF PROCESSES AND ABILI1Y TO DETECT CHANGE
Hallet and P. Black, Editors
