SOIL SURVEY

-29-PART I IMETHODOLOGYMAPPINGA good understanding of the relationships between soil changes and concomitantvegetation and landform changes is mandatory when mapping soi Is i nmountainous wildlands . The most useful tool to extrapolate site information ove rand extended area is the aerial photograph . Since the ground can seldom be see nthrough the vegetative cover, and even then it is impossible to "see" the profil emorphology and material, it is necessary to correlate the non-soil information ofvegetation and landforms to soil information such as horizon sequence, reaction an dmaterial or texture . The introductory discussion of the natural resource informatio nin Part I provides the background upon which the photo interpretations and consequentlythe soils maps are based .Aerial photographs taken August 1973 at a scale of 1 :25,000 were used a sthe basic field tool for delineating soilscape areas . An initial brief reconnaissanc ewas used to set up a tentative legend for identifying map units . The reconnaissanc eexperience was then used to delineate tentative areas by interpretation of aeria lphotographs and to name these according to the tentative legend . Field checking,using soil pits and any other available exposure, allowed refining of the aeria lphotographic interpretations and the legend . As map unit concepts were finalized ,map units were added to and deleted from the legend to fit those concepts .The landscape was first divided on the basis of landforms (Figures 12 and 13) .Thus, for example, moraines were separated from glaciofluvial deposits, floodplains ,alluvial fans, lacustrine deposits and colluvial deposits . The landforms were the nsubdivided on the basis of materials ; calcareous versus non-calcareous and mediumversus coarse textures . The resulting terrain units were then further subdivided int osoilscape groups on the basis of soil development and soil climate as indicated b yvegetation (Figures 14 and 15) . These soilscape group concepts were identified on