The processes that creates gneiss can recreate normal granite if carried on long enough, and gneiss can also form from gabbro or shale. Schist and quartzite may be formed alongside gneiss, along with other types of metamorphic rock formed from igneous rocks. Gneiss is very common and actually forms the majority of the Earth's lower crust, so any deep tunneling encounters gneiss.
Inventoried roadless area. Inventoried Roadless Areas are a group of United States Forest Service lands that have been identified by government reviews as lands without existing roads that could be suitable for roadless area conservation as wilderness or other non-standard protections.
Driftless Area: In northeatern Iowa, parallel with the Mississippi River, lies the Driftless Area. This area was not flattened to the extent of the Young Drift Plains and is characterized by rugged hills and cliffs. What drift that was deposited in this area has been blown or washed away.