Mount Hood (45.4N, 121.7W) is the tallest mountain in Oregon (11,237 feet, 3,426 m) and popular with skiers, hikers, and climbers. It is 45 miles (75 km) east-southeast of Portland, Oregon. Mount Hood is a stratovolcano made of lava flows, domes, and volcaniclastic deposits. Most of the volcano is andesite composition. The main cone of Mount Hood formed about 500,000 years ago. In the last 15,000 years the volcano has had four eruptive periods.