Cane Creek Mountains 300–350 million years ago during the formation and rifting of Pangaea. This earlier range is thought to have had peaks more than high, which would rival the Himalayas, the Andes, and the Alaska Range. However, erosion has worn this old mountain range down. The highest peaks of this old range are now found in the Appalachian Mountains on the eastern coast of North America and in the Anti-Atlas Mountains of Morocco in Africa. The heavily eroded hills of piedmont, including the Cane Creek Mountains, are remnants of the sizable mountain chain. The Cane Creek Mountains lie in the Carolina Slate
Ojos del Salado of fumaroles high on the mountain and recent-looking lava flows, albeit of uncertain age, also argues in favor of a categorization as "active." By these definitions, Ojos del Salado is the highest historically active volcano on Earth. If the older date is accepted, the title of "highest historically active volcano" might reside instead with the somewhat lower Llullaillaco volcano, which certainly has erupted in historic times (most recently in 1877) and is considered active. Salado's rock is predominantly potassium-rich dacite and rhyodacite. Its lavas are high in biotite, hornblende, plagioclase, and opaques, with lower levels of augite, quartz, and hypersthene.