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Geologic Mapping: State Coverage

State Coverage Mapping Pie Chart

Geologic maps provide fundamental knowledge about the physical environment. Consequently, geologic maps are essential to understanding natural, earthbound processes and solving real-world environmental problems which directly affect people, plants, and other animals. The knowledge gained from geologic maps also helps protect us from natural hazards, ensuring a viable environment, and predicting the effects of climate change. Residents, communities, and land managers need geologic maps to plan, develop, and wisely use Alaska's natural resources — from building roads and pipelines to extracting precious minerals. The people of Alaska rely on geologic maps to make informed decisions about their land and Alaska's resources and future viability.

Small-scale mapping at 1:250,000 or beyond provides regional context for understanding framework issues over broad areas. The U.S. Geological Survey completed a compilation of the state at a nominal scale of 1:584,000, which was published both as a printed product and as digital data. The compilation contains older 1:250,000-scale and limited 1:500,000- to 1:63,360-scale interpretations and other data, however, and needs to be updated as new information becomes available.

The Alaska Division of Geological & Geophysical Surveys' (DGGS's) energy- and mineral-resource programs typically map at 1:63,360 or 1:50,000 scale. About 20 percent of Alaska is geologically mapped between the scales of 1:100,000 to 1:50,000, and at the current rate of mapping, many decades (about 450 years) will be needed to complete coverage at this medium level of geologic detail. Note that 1:100,000-scale mapping in the contiguous US is considered regional scale. Many states have complete geologic coverage at this scale and are now remapping areas. Other, smaller states have also made great strides toward serving GIS-ready datasets, while only about one percent of mapping data is digitally available in Alaska.

Additionally, most current mapping in the contiguous US is conducted at 1:24,000-to-1:25,000 scale or larger. Large-scale maps, describing site-specific geologic features or covering communities and infrastructure, exist for about one percent of Alaska. A great deal of work needs to be completed in Alaska, at all scales of geologic mapping, as coverage in Alaska dramatically lags behind the amount of data available in the contiguous states. Limited quality surface information, and the near-complete lack of subsurface data, also hinders any forays into 3-D mapping.

Scale Mapped Digitally Available Comments
1:250,000 95% 84% Much is old and needs re-doing
~1:63,360 20% 84% Majority of contiguous US mapped at 1:100,000
~1:24,000 1% <1% Most current mapping in contiguous US at this scale
3-D mapping 0% 0% Recent focus on 3-D mapping
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