• Mountain ranges are formed as a result of the collision of tectonic plates.
• Young orogenic mountain ranges have formed tens of millions of years ago. They are characterized by tall mountains, sharp peaks and steep slopes.
• Old orogenic mountain ranges have formed hundreds of millions of years ago. Exogenic processes have worn down these mountain ranges, making their peaks flat and their slopes gentle.
• Many mountain ranges contain volcanoes.
• Key words: mountain range, young orogenic mountain range, old orogenic mountain range.
• Mountain ranges: The Rocky Mountains and the Andes (the Americas), the Himalayan Mountains (Asia), the Alps (Europe).