Relief Model of Kauai
		Relief model of the island of Kauai viewed obliquely from the south. The Puu ka pele slope, west of Waimea Canyon, is underlain by the Napali Member of the Waimea Canyon Basalt, which represents the prominent shield-building stage of the mountain/island volcano that emerged above the sea around 5.1 million years ago. The Waimea Canyon scarp probably represents a major collapse at the beginning of the post-shield (or declining) stage (approx. 4.25-4.00 million years ago). Post-shield alkalic volcanics of the Olokele Member of the Waimea Canyon Basalt may have infilled a major caldera-like collapse structure to form the present-day broad summit area of Mt. Waialeale and the Alakai Swamp; similar volcanics of the Makaweli Member of the Waimea Canyon Basalt also partly infilled the graben-like Makaweli depression. Such post-shield volcanic flows continued until around 3.92 million years ago. The major east-west trending Haupu Mountain ridge, between Poipu and Lihue, is composed of the Haupu Member of the Waimea Canyon Basalt, and is a probable structural remnant of the original shield-building, and/or post-shield, volcanic stage(s) of the island. After a brief stage of quiescence and erosion (lasting only 0.25-0.30 million years), rejuvenation stage volcanics, represented by lava flows and explosive volcanics of the Koloa Volcanics (age 3.65-0.52 Ma), covered the eastern portion of the island, including partial infilling of the Lihue depression. Very late stage explosive volcanic vents and cones of the Koloa Volcanics such as Kilohana Crater, Kilauea Crater to the north, and 35-40 other smaller but similar features are present throughout the eastern portion of the island. The very steep eastern facing scarp of Waialeale, formed in part by collapse of the Lihue Basin, produces a dramatic orographic effect by which warm, moisture-laden trade winds from the northeast are forced upward and cooled to generate the condensation that gives Mt. Waialeale the reputation as having one of the highest rainfalls in the world. (from Macdonald, Abbott and Peterson, 1983)