ABSTRACT: 38. Project Unit 00-033. Satellite-based engineering geology terrain studies for Ontario's far-north.

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Approximately 20 years ago Northern Ontario Engineering Geology Terrain Studies (NOEGTS) were completed for that part of the Canadian boreal forest region lying south of latitude 51 o N (Gartner et.al. 1981). Each study included a 1:100,000-scale terrain map that was based almost entirely on the interpretation of air photographs with limited field checking. The map legend contains information on surface material type, landform, topography (relief) anddrainage condition. The NOEGTS terrain maps produced previously have been quite useful in providing regional information on geological conditions of the landscape. These conditions affect or determine resource capability of an area as well as identify and outline possible constraints (Gartner et.al. 1981). They have been used extensively for regional planning purposes in forest management, drift exploration and in ecological land classification studies by both private and public organizations. The area north of 51 o N latitude is in need of such terrain information. It is a part of Ontario's new frontier for the mineral and forest industries. NOEGTS maps would be expensive to create in the traditional manner because of the vast area to be covered, limited access and ground truthing that would be required. The 2-year joint Ontario Geological Survey and Canada Centre for Remote Sensing (OGS-CCRS) project,described herein, attempts to undertake pilot studies designed to create terrain maps using the integration and interpretation of various types of remotely sensed imagery, digital elevation models, their derivatives and geological depositional models. It is suggested that information on the various legend components: material, landform, topography and drainage, can be derived from the interpretation of digital elevation models (DEM), their derivatives and remotely sensed imagery through the use of establishedlandform/sediment models. The DEM and derivatives, such as hill-shaded DEM, slope, and elevation range models, in conjunction with LANDSAT 7, RADARSAT, and high resolution satellite imagery, are being used in several pilot areas to determine if image-based terrain maps can be created portraying similar information to that of the NOEGTS maps. Six (6) pilot areas were chosen from within the area of Ontario™s boreal forest bounded by Latitudes 51 o and 54 o N and Longitude 87 o W and the Manitoba border. The project began in April, 2000 and to date, emphasis has been placed on data collection, data processing and methods development. Data collection and processing included the construction of hydrologically-conditioned digital elevation models (DEMs) of the entire study area. Created by the Geomatics Service Centre (Ministry of Natural Resources, Peterborough) for this project, the DEMs were generated using elevation information, the drainage network and water polygons in the interpolation process. This process creates a higher quality representation of the land surface as a result of incorporating drainage enforcement into the DEM algorithm. The DEMs were processed for the entirearea in 4 batches and the individual 1:100 000 scale tiles of the 47 areas subsequently clipped out. In addition, the Geomatics Service Centre prepared hill-shaded DEM coverages (ArcInfo TM ) for all 47 tiles. Several types of remotely sensed data have also been acquired for use in this project. Complete RADARSAT data coverage is currently being assembled and Landsat 7 Extended Thematic Mapper (ETM) multispectral and panchromatic data is being acquired for the entire study area. Two scenes of IRS-1-C imagery were purchased for the Trout Lake and Pikangikum pilot project areas. Processing of the remotely-sensed imagery is underway for all of the pilot project areas. This past summer, methodology work concentrated on the Trout Lake and Pikangikum pilot project areas located approximately 550 km northwest of Thunder Bay. The communities of Red Lake, Balmertown, Cochenour and Pikangikum lie within these areas. Most of the work has been concentrated in the Trout Lake area with the goal to produce a prototype map for this area by November (Barnett et al. in press). The Trout Lake and Pikangikum areas are characterized by irregular bedrock-dominated terrainunderlain by Precambrian igneous and metamorphic rocks (Canadian Shield). The area was last glaciated during the Wisconsinan Stage by the Nouveau Québec Sector of the Laurentide Ice Sheet. During deglaciation of the area, a large, ice-contact glacier-fed lake fronted the ice margin (glacial Lake Agassiz).The interactions of the glacier with the glacial lake controlled depositional environments and, hence, the distribution and types of landforms, origin (glacial, glaciofluvial or glaciolacustrine), material types and sediment distribution. Direct glacial sedimentation was deposited primarily under the glacier (till) or along the ice margin or grounding line (flowtills). Subglacial landforms include till plains and fluted till plains, drumlins and eskers. Ice-marginal landforms include one large end moraine, the Lac Seul Moraine (Prest 1963) which contains deltas and subaqueous fans, and grounding line fans commonly referred to as DeGeer moraines. The Lac Seul Moraine is considered by some to be a very large grounding line fan produced during acatastrophic release of stored meltwater within the Laurentide Ice Sheet (Sharpe and Cowan 1990). Sedimentation into the glacial lake was dominated by density underflows as a result of density differences between the incoming sediment-charged meltwater and the lake water. In this setting, thedistribution of fine-grained sediments is controlled by lake-bottom topography and elevation, with sediments being preferentially deposited in topographically low areas. Abandoned shoreline features, beaches, bars and spits, of glacial Lake Agassiz are well developed along the Lac Seul Moraine and otherisolated hills of ice-contact sediments. Several levels of this lake are recorded. Wave and current action in this lake has also produced large areas of bedrock outcrop, washed clean of any pre-existing glacial sediment. Many small wetlands occur in bedrock-dominated terrain and in areas of low relief, grounding line fans. Larger areas of wetlands occur within the broad plains underlain by glaciolacustrine fine- grained sediments. With the above depositional models and landscape conditions in mind, the methodology developed included the direct interpetation of the DEMs, as well as several derived products that were created to aid in the interpretation of landform, material-type, relief and drainage conditions. These included the hill-shaded DEMs, slope, aspect, and elevation range models. These derived products were produced using ArcInfo TM and ArcView TM software packages. Landsat 7 Extended Thematic Mapper (ETM) multispectral and panchromatic data, IRS-1C panchromatic and RADARSAT data were also used in theinterpretation. Initial geological analysis was based on individual image maps of one degree of longitude and one-half degree of latitude. Image maps were created using each of the 4 sensor types. A method was then devised to combine the sensors with the hill-shaded DEM data, and image maps of combined products (ETM multispectral + DEM, ETM panchromatic + DEM, IRS 1-C panchromatic + DEM, RADARSAT SAR + DEM), were also created (Singhroy et al. in press). The color or black and white image maps were printed at a scale of 1:100 000. The maps were used in the field and interpreted visually by integrating the field information. Field visits to the Trout Lake and Pikangikum areas were undertaken during the summer of 2000.Observations on material type, forest cover and terrain conditions were made at selected sites as ground truth for image interpretation. Material relationships were observed at some sites and appropriate geologic models identified and refined. Analysis of the DEM, the derived hill-shade, slope and aspect maps aid in mapping the various landscape elements. The hill-shaded DEM provides a general overview of the terrain. Areas of glacial and glaciolacustrine sedimentation occur as smooth areas on this image and rock-dominated terrain have a very irregular appearance. The Lac Seul Moraine, for example, stands out as a dominant, linear topographic high. On the slope map, the moraine has steep slopes on the proximal side and gentler slopeson the distal side. Ice-marginal deltas and subaqueous fans have their own characteristic shape but slope relationships are similar to that of the end moraine. The granular nature of the materials associated with these landforms (predominantly ice-contact stratified sediments) and their positive relief makes these sites very well drained and allows them to support the growth of jack pine (Pinus banksiana). Glaciolacustrine sediments and subglacially-deposited till form plains which are recognizable on the DEM and slope maps. Plains of lower elevation tend to be underlain by glaciolacustrine materials and plains at higher elevations are commonly underlain by till. Only a few of the larger, generally low-relief, linear grounding line fans are recognizable on the DEM, however, these forms can be seen as promontories and/or linear islands within the area lakes and as linear tonal variations on the ETM and IRS images. Areas of irregular topography and short complex slopes are either bedrock-dominated areas or stagnant ice deposits (small fans and kettles). Separation of these 2 area types, as well as several of the others discussed above, can be done in association with the remotely sensed images based on forest variability. The relief component of the legend can be derived using a 30x30 pixel filtering technique of the range in elevation values in the DEM. The resultant data can then be classed into the low (<15 m),moderate (>15 m to <60 m) and high (>60 m) relief classes used in the NOEGTS maps. The main components of the NOEGTS maps legend are material type, landform, topography and drainage condition. Information on landform and topography and inferences to material type, based onlandform/sediment models, can be provided by the analysis of the DEM and RADARSAT images. Information on material type and drainage condition can be interpreted from the remotely sensed imagery. For example, there is a high geobotanical correlation between well-drained areas of sand and gravel anddense jack pine forest cover. Combining remotely sensed data and DEM derivatives within a GIS are a powerful method to delineate terrain units at a scale of 1:100 000. The most useful visual image sources for terrain mapping are the ETM/DEM composite and the IRS/DEM composite. Although the highresolution of the IRS does provide greater detail for terrain mapping, the ETM/DEM composite is more cost efficient and still suitable for terrain mapping at 1:100 000.

Bibliography of Canadian Geomorphology