DIGITAL CAPTURE AND PRESERVATION OF HISTORIC MINING DATA FROM THE KEWEENAW COPPER DISTRICT, MICHIGAN

The Michigan copper rush starting at Copper Harbor in 1843 led to 150 years of mining that produced ~7 x 10⁶ MT of copper, attracted ~100,000 persons from 40 countries, and profoundly influenced understanding of Lake Superior geology, advances in mining technology, and the region’s pattern of life. Many companies invested significantly in trenching, coring, and mining operations that generated an enormous body of geologic information. USGS efforts to map bedrock geology and to assess mineral resources have compiled much of this information as bedrock geology maps with supporting cross sections and reports. Though available online in image format, these products are the tip of an iceberg of source data not easily accessed or not used in their compilation. Paper records and microfiche that decay with time are stored at various locations, some of them difficult to monitor and access. Many groups could benefit from improved access to this vast amount of information. Therefore, we began a ‘skunk-works’ project to identify and gather information into a digital repository, to extract it into tabular databases, and to explore how to make it available to scientists, industry, land-use planners, and the general public.

The exploratory phase of the project is to inventory available data, establish procedures, and demonstrate feasibility. We started with drill holes, trenches, and mine openings posted on USGS geology maps of the Keweenaw Peninsula. Features were symbolized in Google Earth from georegistered maps, assigned unique codes, and recorded with their data in tables having a common layout (Stage 1). Derivative tables contain data unique to a class, such as azimuth and inclination of drill holes found on core logs (Stage 2). Data captured up to this stage are useful for positioning and orienting features on maps and in subsurface models. Stage 3 captures geologic data as a function of location in a feature, e.g. distance along a drill hole. Such information is found in core descriptions at the Keweenaw National Historical Park, the USGS Archives in Denver, old reports and plates, and requires careful transcription to extract from image records. Besides making these data types available to the public in an easy-to-access format, we hope to build subsurface models that can benefit research, mineral exploration, and land-use planning.