Geological Map of the Future: Digital, Interactive, and Three-Dimensional

Extended abstract

Geological survey agencies are developing methods for government geological mapping in the post-paper map era. Surficial and bedrock maps are being digitized and reconciled, while multiple generations of legends are being made accessible in a categorized format. Regional three-dimensional (3-D) geological models that integrate soils and geology, surficial and bedrock geology, as well as onshore and offshore, are increasingly in demand as the information, technology, and protocols to build them progress. Applications such as regional groundwater modeling require digitizing, reconciliation and assembly of a digital elevation model, bathymetry, offshore geology, soils, surficial geology, public domain drillhole and geophysical data, bedrock maps and existing stratigraphic models typically expressed as structure contours. New stratigraphic modeling, particularly required for surficial unconsolidated deposits in many regions, requires information from cored holes logged by geologists, as well as geophysical surveys. These high-quality results are extrapolated laterally using drillhole data, commonly large quantities of water-well data of varying resolution and reliability. Much effort is required to adequately georeference the drillhole data, and to parse large numbers of unique lithological descriptions. Stratigraphic modeling methods ideally use all data and an approach that permits judgement in the acceptance or rejection of data, while interpolation and extrapolation are guided by genetic insights. Models are best captured as a grid of predicted stratigraphy profiles that convey expert opinion on interpolation and extrapolation from the data points. Reconciliation of mapping with that of neighbouring jurisdictions is a key step, as is balancing subjective definition of strata with more objective geostatistical approaches to characterizing the heterogeneous physical properties of the strata. Progress is readily achievable in undeformed strata, while deformed strata present far greater challenges. Increasingly, databases of observations and measurements are being retained alongside the interpreted model, and models are being assigned varying confidence levels, such that the result is seen not as an end but as a means for prioritizing new mapping. Current activity is broadening our reliance not only from paper maps to digital models, but also from plan view maps to drillhole databases, to 3-D models, to dynamic models such as groundwater flow models. Pressing user requirements demand that geological survey work advances rapidly along this progression.