The Great Smoky Mountains are among the oldest mountains in the world, formed approximately 200-300 million years ago. They are unique in their northeast to southwest orientation, which allowed species to migrate along their slopes during climatic changes such as the last ice age, 10,000 years ago.

The Great Smoky Mountains are among the oldest in the world, but they do not hold the title of the absolute oldest. Formed roughly 200 to 300 million years ago during the collision of tectonic plates that created the supercontinent Pangea, they are part of the Appalachian chain. While ancient, they are youngsters compared to the Barberton Greenstone Belt in South Africa or the Pilbara Craton in Australia, which date back over 3 billion years. However, in the context of famous mountain ranges, the Smokies are significantly older than the Himalayas (approx. 50 million years) or the Rockies (approx. 80 million years). Their rounded, "smoky" appearance is a direct result of hundreds of millions of years of erosion, which has worn down what were once jagged, Himalayan-sized peaks into the lush, rolling ridges we see today.