So the physical boundaries of the Cliff Mine nominated property have been defined. But what of the time period of significance? This determination is important for considerations of future management, as well as refining the scope of possible narratives about the site useful for future funding (grants, for instance).
For starters, a nominated property must be at least 50 years old, since that is the cut-off for the National Register. The Cliff was long dormant by 1964, so of course there is no question as to its appropriateness for nomination. The mine’s use/period of activity can be divided into three concurrent phases: the Pittsburgh & Boston Mining Co. period, the Cliff Copper Mining Co. and Tamarack Mining Co. periods, and the Calumet & Helca Mining Co. period.
The Pittsburgh & Boston Mining Co. period covers the mine’s beginnings (1845) up to 1871, when the mine was sold to Marshall Simpson (who the next year formed the Cliff Copper Mining Co.). The first phase is the high point of the mine’s lifespan, when its built footprint was greatest, and the community of Clifton was first developed.
The second phase (1871-1910) was marked by a decrease in production, along with a decrease in the size of the community of Clifton. The Cliff Copper Co. worked the site until 1878,when the mine was turned over to tribute miners who worked over the tailings piles, waste rock piles, and areas underground already opened. Eventually the Tamarack Mining Co. came to own the property. In the early 1900s, they focused on an area where the Kearsarge Lode crossed the fissure vein, and even built a small wood-framed shaft house on the remains of the original Avery shaft location. This period also marked the time when Henry Warren’s stamp mill was in operation, an archaeological feature excavated in 2012.
The third phase of the mine took place over the years 1910-1932. In 1910, the Calumet & Hecla Mining Co. began a concentrated effort to consolidate mining properties all over the Copper Country. Several older mines were purchased and redeveloped in the hope that large lode deposits could be located below once fertile fissure and mass lodes. The Cliff was just one such location gobbled up during this period of consolidation. C&H reopened the mine, extended it downward and northward, and drilled extensively to the southeast of the property. By 1932 the company had mostly ceased all active extraction at the Cliff. Years later, C&H reprocessed the tailings at the Cliff, but the evidence for this reprocessing is no longer present (in fact, the tailings were never returned, so if anything, the evidence is a LACK of tailings).
So the question is: should the period of significance be limited to just the first phase, or should the later phases be included? There is no question that the first phase of the mine’s use is significant. The Cliff mine under the management of the Pittsburgh & Boston Mining Co. became the first profitable copper mine in Michigan, and proved that the Lake Superior mining district was a viable investment for Eastern capital. The third phase (C&H period) is also historically significant. There is still physical evidence of C&H’s consolidation of older mining properties seen at Cliff. The foundations of the compressor house, built just below the Avery shaft location, are still present, as is the conical rock pile that half-buries the No. 4 engine house and smoke stack.
The second/middle phase is the period of concern. The mine was active, on and off, throughout the last quarter of the nineteenth century. However, the activity was considerably less, and few if any features remain of that period. The workers during this period were primarily using the structures and technology constructed during the first phase. Two things are to be considered for inclusion, however. The first is Warren’s mill. It was built and used during this period, and it’s remains are present and well preserved. The other factor is that the community of Clifton was still occupied. This provides a continuity from the first phase to the third that argues for inclusion.
Therefore, the period of historic significance for the Cliff Mine nominated property is 1845-1932. When considering the entirety of active mining in the Copper Country, this makes the Cliff one of the longest lived industrial sites in the area.
So what’s next? We get into the nuts and bolts of Classification and Function, two seemingly simple procedural formalities that actually require a lot of thoughtful decision making.