Bernal, Mexico. The monolith was thought to have been formed 65 million years ago during the Jurassic period. This peak, the Pena de Bernal, is a popular destination for hikers and rock climbers. This is one of Mexico's highest monoliths rising to 1421 feet Above Ground Level. Considering that Benal is about 6700 Above Sea Level (ASL), this places Bernal Peak at about 8100 ASL.