Anatomy of the Underground

The adit we discovered at Copper Falls in only part of a much larger labyrinth of tunnels and shafts that comprise a Copper Country mine. The copper rich rock that mines sought were localized and concentrated into areas called lodes. Due to the geological forces that shaped the Keweenaw, copper bearing lodes were long and narrow strips of rock - running generally parallel to the shoreline. These lodes are only a couple hundred feet in thickness and extend for miles on a westward dip under Lake Superior. Because of this, mines in the Copper Country are generally very deep and narrow in structure.

A mine’s structure can be easily mapped flat along the lode itself. Running along the dip of the lode are inclined shafts. These are deep holes running along the lode itself in which men and materials are transported. Branching off of these shafts are long tunnels running perpendicular to the shafts and along the lode from north to south. These are called drifts, and from these the major mining is done underground. Drifts were driven off of the shafts at regular intervals of depth (about 100 feet at the turn of the century), creating the levels of the mine. Drifts often connected two or more separate shafts along the lode, creating paths for air to enter and exit the mine readily.

As the region matured, shafts became further and further apart along a lode. This often resulted in distances of thousands of feet along drifts between shafts. To facilitate the movement of air underground and to allow for vertical movement of miners and equipment underground between these shafts, winzes were built. These were similar to shafts rising vertically between levels along the dip of a lode but never broke surface. They were usually smaller and more shallow then their shaft brethren, but often served the same purposes.

Copper Country mines usually were mines upward from the drifts - up into the lode from below. This facilitated the removal of waste rock and copper by the use of gravity. The large hallows from which copper and rock had been removed were called stopes. In some copper rich mines, stopes could reach cavernous proportions, sometimes reaching up to the level above. The ceiling along these stopes - called the hanging wall - could become highly unstable. Companies would leave pillars or rock along stopes as supports, or (in the case of C&H) use timber supports in a virtual underground forest to hold up the hanging wall.

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