About terrain. You'll find topics on defining plains, their types, and how they're formed, as well as on mountains around the world: the Alps, Himalayas, Andes, Rockies, Atlas, and materials on the mountains and plateaus of the Arabian Peninsula, such as Tuwaiq and Najd. There's also material on mountains with historical and religious significance, such as Mount Sinai and Mount Musa, with references to the world's highest peaks and common questions answered.