mountains paralleling for 37 miles (60 km) the eastern coast of Oahu island, Hawaii, U.S. The range was formed by volcanic eruptions and has an average width of 13 miles (21 km). The original caldera, 6 miles (10 km) long and 4 miles (6 km) wide and the second largest in the state, is now a hill near the town of Kaneohe. The Diamond Head and Koko Head capes (east of Honolulu) resulted from the range's last volcanic activity, more than 10,000 years ago. Because of its wind-facing position, the Koolau (“Windward”) Range traps precipitation, which results in numerous streams and waterfalls. The range's most characteristic feature is a serrated precipice, the pali (“cliff”), that rises abruptly on its eastern side and reaches varying heights (500 to 2,500 feet 【150 to 750 metres】) 2 miles (3 km) from the sea. The highest point in the range is Konahuanui, which is actually two peaks (3,150 feet and 3,105 feet 【960 metres and 946 metres】) and lies at the head of the Nuuanu Valley. Two cliff passes—Nuuanu and Waimanalo palis—cut through the range, there pierced by highway tunnels. The 1,200-foot (366-metre) Nuuanu Pali is associated with the conquest of Oahu by Kamehameha I in 1795, when his troops forced Oahu warriors up the valley and over the cliff to be killed on the jagged rocks below. The Koolau's more gradual western slopes form a picturesque background for Honolulu. Western lava flows created the Schofield Barracks, a saddle (ridge) 14 miles (22 km) long and 5 miles (8 km) wide between the Koolau Range and the Waianae Range (which parallels the island's west coast).