Mapping News: The Future of Geologic Mapping in Utah, New Tools and Techniques

by Stefan Kirby, Matthew Morriss, Lauren Reeher, Zachary Anderson, Donald Clark, Keilee Higgs, and Emily Kleber

Geologic map of the Bountiful Peak quadrangle. Different colors indicate different rock units.

Geologic map of the Bountiful Peak quadrangle.

Geologic maps form the basis for a multitude of natural resource-related decisions. The maps and their derivatives define the character and extent of Earth’s geologic history, resources, and hazards. As such, geologic maps are essential to discovering, researching, and obtaining the natural resources humans rely on daily. To satisfy the need for this information, the Utah Geological Survey (UGS) has been creating and publishing geologic maps since its inception nearly 75 years ago.

Geologic mapping is a rapidly evolving discipline that employs a range of modern techniques including satellite and drone imagery, multispectral analysis, 3D visualization, custom lidar (high-resolution topography), complex relational databases, and the new and evolving field of machine learning, a subfield of artificial intelligence (AI). In the Geologic Mapping Program, we are actively upgrading our map-making process to include these new tools. Our goal is to produce high quality geologic maps faster than ever before to serve the diverse geoscience needs of Utahns.

3D visualization is a time-tested approach to geologic mapping, which began with the earliest widely available aerial photography following the first World War. This technique involves a simple parallax produced by looking at appropriately paired aerial photographs (stereo photos) through a magnifying scope. Landforms and geologic units could be differentiated and then traced on the paper photographs. This technique formed the basis of geologic mapping for over 80 years and when done carefully yielded high quality spatially accurate maps. The primary downside of this method was the difficulty of editing geologic lines on paper photos and potential problems with transferring geologic map data to rectified basemaps.

With the onset of digital geologic map creation around 40 years ago, new modes of 3D visualization were developed. Initially these techniques used proprietary software that utilized a unique data structure, which created a range of problems and additional work that slowed map production and publication. The UGS Geologic Mapping Program is currently investigating and refining a 3D stereo mapping and visualization technique and workflow that will allow start-to-finish map publication in a single software and data structure using ArcGIS Pro.

Because the UGS now uses ArcGIS Pro for most mapping tasks including lidar analysis, database management, linework, and final map preparation, we are transitioning 3D stereo mapping from the previously used software into our existing ArcGIS Pro workflow. Further, previous UGS GIS experts have created 3D stereo models that cover the entire state, permitting mappers to view any location in the state on screen in 3D. These models can be visualized with 3D glasses in current ArcGIS Pro projects where mappers can view and edit existing linework in 3D. This method gives the mapping geologist a realistic perspective on the landscape, key for understanding geologic processes.

The UGS mapping group is also using various dronesourced data collection methods to facilitate geologic mapping. We recently used a lidar-scanning drone to survey a rock glacier in Gad Valley in the Wasatch Range. Rock glaciers are talus-covered bodies of intermittent ice that move downhill like ice glaciers, but at much slower rates (for example, less than a few inches a year). The Wasatch Range has over 60 rock glaciers, many of which may be moving. These features could represent potential water resources through the melting of internal ice or even geologic hazards if they become unstable. By deploying the new lidarscanning drone, we collected a high-resolution, 3D image of the rock glacier. Repeat imaging enables the precise measurement of changes in the glacier’s volume, movement, and structural integrity over time, which is crucial for assessing its potential impact on the surrounding environment, infrastructure, and the operations of Snowbird ski resort. Moreover, this lidar scanner is only one of a host of drone-based instruments (multispectral camera, thermal camera, etc.) that we can use to build more comprehensive datasets to support mapping projects.

The drone survey is part of a project to complete a new 1:24,000-scale geologic map of the Dromedary Peak quadrangle in the Little Cottonwood Canyon area of the Wasatch Range. Many of the Quaternary deposits present in the quadrangle have been poorly described or not previously recognized. Now, with both aerial- and drone-based datasets, we are working on a comprehensive mapping effort and description of these units.

Machine learning is an ever-growing field of digital decision making and data creation. In the field of geologic mapping it has been investigated in various forms for several decades. The ultimate goal of using AI would be to automate much of the geologic map creation process, which could greatly accelerate map creation and allow mapping geologists to cover much larger areas and focus on complicated geological issues while still creating high quality maps. The workflow would use various input data including imagery, elevation, and training. Training data could consist of geological relationships defined at discrete sites and/or previously published maps. AI would then be leveraged to make linework and accompanying geologic maps based on observed repeatable relationships and characteristics inherent in the input data. So far, however, this workflow has shown that repeatable relationships are difficult for current machine learning algorithms to pick out at the resolution and quality of human mappers. In practice, automated techniques can map simple geologic contacts in some areas. However, input and training data fine-tuning requires trained geoscientists and, in the end, yields a geologic map that is much simpler and lower quality than the human-created standard for maps of a given scale.

Geologic maps published by the UGS are the foundation of a broad range of natural resource and land use decisions. The process of map creation is ever evolving and the UGS Geologic Mapping Program is actively pursuing new techniques and solutions to efficiently create accurate maps to serve Utah’s citizens. The future of geologic mapping in Utah is bright and is growing in new avenues as new technology and techniques become available.