Geology
The Black Mountains consist primarily of Precambrian gneiss and schists formed over a billion years ago from primordial sea sediments. The mountains themselves were formed roughly 200-400 million years ago during the Alleghenian orogeny, when the collision of two continental plates thrust what is now the Appalachian Mountains upward to form a large plateau. Weathering and minor geologic events in subsequent periods carved out the mountains.
During the last Ice Age, approximately 20,000-16,000 years ago, glaciers did not advance into Southern Appalachia, but the change in temperatures drastically changed the forests in the region. A tree-less tundra likely existed in the Black Mountains and surrounding mountains in elevations above 3,500 feet (1,100 m). Spruce-fir forests dominated the lower elevations during this period, while hardwoods "fled" to warmer refuges in the coastal plains. As the ice sheets began retreating 16,000 years ago and temperatures started to rise, the hardwoods returned to the river valleys and lower slopes, and the spruce-fir forest retreated to the higher elevations. Today, the spruce-fir forest atop the Black Mountains is one of ten or so spruce-fir "islands" remaining in the mountains of Southern Appalachia.
Read more about this topic: Black Mountains (North Carolina)