Volume 9, numéro 1, march 1982

EN :

Recreational activities and increasingresource development in the highestparts of the Canadian Cordillera willresult in permanent high-density settle-ments along the flanks of hithertosecluded mountain valleys. In this envir-onment the possibility of damage tohuman works, such as transportationroutes and towns, by debris flows orlarge-scale slope failure has to beappraised, preferably prior to the onset ofmajor construction activity. Two millen-nia of documented adjustments of set-tlement pattern to a variety of slope con-ditions in the densely populatedEuropean Alps offer a number of alterna-tives in approaching this problem byactive (technical) or passive (zoning)measures and by the recognition of theresidual risk- For areas of proposed per-manent housing, mass movements with aprojected rate of recurrence of more thanone event in 100 to 300 years should beassessed seriously. In precipitous moun-tain valleys there are very few areas forwhich risk can be assumed to be nil - par-ticularly if projected time intervals are inexcess of 500 years. A certain amount ofresidual risk thus has to be accepted bythose inhabiting or moving through highmountain terrain. Quality of sloping ter-rain will also figure increasingly in com-prehensive resource management(forests, tourism, fishing, andtransportation).

EN :

New concepts of western Cordillerangeology involve the assembly of exoticblocks of crust through large northwardmovements and strike-slip faulting. Thesecan only be valid if the regional platetectonic framework provides a suitablemechanism. The geometrical recon-struction of global plate motions showsthat throughout the last 100 Ma, platemovements along the western marginhave been appropriate. Movement hasbeen northward relative to North Americaat high rates and has alternated betweenconvergence and north-westerly strike-slip faulting. Local details must becompatible but cannot be resolved bysuch broad reconstructions.

EN :

In order to illustrate how glacialstratigraphy may become influenced bythe subjectivity of researchers, the grainsize composition of till will be discussedas an example. Most particle size data donot refer to the entire till, but mainly to itsmatrix, plus smaller clasts. Though thegranulomere data, even if just referringto till matrix, are considered to be reliableand objective, various amounts of subjec-tivity enter the analytic results during thesampling, pretreatment, analyses andstatistical evaluation of data.

The subsequent interpretation involveseven more subjectivity. This will beillustrated by using tills of SouthwesternOntario and Denmark as examples. Whilecolour and texture of till once used to bethe main criteria for differentiation andcorrelation of tills, more complex multiplecriteria are applied now. During the last15 years a score of genetic varieties oftills have become recognized, each ofthem playing its role in stratigraphieinterpretation. Now more attention thanbefore is paid to glaciotectonicdeformations and fabric in decipheringstratigraphy of glaciogenic sequences.

Quaternary glacial deposits cover mostof Canada. If their stratigraphy has beenproperly deciphered, the extraction ofQuaternary economic deposits and theplanning of major construction projectsmay be done rationally. The knowledgeof glacial stratigraphy is useful also inhydrogeology and in planning waste dis-posal. In the search for bedrock ore depo-sits by indicator tracing, anunderstanding of Quaternary glacialstratigraphy is essential in areas withmore than one layer of glaciogenicdeposits over bedrock.

EN :

Glacial dispersal, the process of glacialerosion, transportation and deposition,has distorted the bedrock signatures onoverlying surficial sediments and soils inmost of Canada. Buffering components,such as carbonate minerals, which miti-gate the effects of acid rain have beendispersed across Precambrian terrane ineastern Ontario in patterns that reflectseveral principles of glacial dispersal.Dispersal trains of boulders, minerals,and trace elements may enhance the sizeof mineral exploration targets by severaltimes. By using appropriate analyticalstrategies and knowledge of dispersal,the source mineralizations can be found,as illustrated by an example of dispersalof nickel from the District of Keewatin.One other way dispersal principles havebeen applied has been to calculate thevolume of material dispersed from a par-ticular source outcrop. Dividing thatvolume by outcrop area yields averagedepth of glacial erosion, an importantparameter to consider in selecting mini-mum depths for burial of long-lived radio-active waste.

EN :

All soils that are now farmed have beenformed or modified by late Cenozoicevents. Where these events have beendramatic with glaciers and plate tectonicprocesses actively intervening, old soilshave been obliterated and replaced bynewer, inherently more fertile materials.In more placid regions, soils that origi-nated on Tertiary and even Mesozoic land-scapes persist, and continue to evolvetowards states of low fertility. The inhe-rent fertility of soil, a renewable resource,is largely ignored in modern mechanisedagriculture in favour of chemicalfertilizers largely mined from non-renew-able deposits. A saner attitude onceexisted, still exists in at least part of theThird World, and should be re-examinedas a possible basis for future strategies.

EN :

This discussion considers two aspects ofenvironmental health and Quaternarygeology. One aspect considers the inhala-tion of dusts derived from unconsoli-dated sediments, and the other aspectconsiders ingestion and the "waterfactor". Both of these aspects of environ-mental health require mineralogical andgeochemical information regardingQuaternary sediments, and most oftenthere are little data available.

EN :

The municipal water supply for theKitchener-Waterloo-Cambhdge region ofOntario is provided by wells in Quater-nary gravels. There is justified concernthat future needs cannot be provided forunless a new source is found. Thefavoured solution is a pipeline to LakeErie at a very high cost ($150 million inthe early 70s). Many informed geologistsand engineers believe that additionalgroundwater supplies are available, andperhaps sufficient to meet the forecastdemands. The key factor in a technicalsolution to the problem is better data onthe Quaternary stratigraphy. Funds havenot been made available for basicstratigraphie studies using moderntechniques and as a consequence hydro-geology cannot be used effectively indealing with the problem.

The inadequacy of geologic data is notlimited to this region. Basic geologicmapping is lacking generally for assess-ment development and protection of ourgroundwater resources, and somehow wehave to convince government officialsand funding agencies that it will pay tocorrect this deficiency.

EN :

Man has become the greatest agentmodifying surface environmentalsystems. Our knowledge of the balancebetween these systems is inadequate andat present we cannot predict theconsequences of major perturbations.Perhaps the greatest problem facing ourscience is the understanding of climatebut if such knowledge is to be obtained,the record must be extracted from rocksnear the surface of the earth.