Remnants of four aggradational terraces in the lower 45 km of the main branch of the Waipaoa River have been correlated with cold/cool climate episodes of the Otiran glaciation. The youngest of the aggradation levels-the Waipaoa-1 terrace-has the c. 14.7 kaRerewhakaaituTephra as the oldest part of the coverbed sequence, indicating cessation of aggradation about 16 ka BP. This terrace is broadly correlated with Ohakean-aged terraces in other parts of the North Island. The second most recent episode of aggradation-the Waipaoa-2 terrace-is slightly older than G98038

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The origin and development of erosion-modified, erosion-transformed, and erosion-induced depressions in volcanic terrains are reviewed and systematized. A proposed classification, addressing terminology issues, considers structural, geomorphic, and climatic factors that contribute to the topographic modification of summit or flank depressions on volcanoes. Breaching of a closed crater or caldera generated by volcanic or non-volcanic processes results in an outlet valley. Under climates with up to F2000-2500 mm annual rainfall, craters, and calderas are commonly drained by a single outlet. The outlet valley can maintain its dominant downcutting position because it quickly enlarges its drainage basin by capturing the area of the primary depression. Multi-drained volcanic depressions can form if special factors, e.g., high-rate geological processes, such as faulting or glaciation, suppress fluvial erosion. Normal (fluvial) erosion-modified volcanic depressions the circular rim of which is derived from the original rim are termed erosion craters or erosion calderas, depending on the pre-existing depression. The resulting landform should be classed as an erosion-induced volcanic depression if the degradation of a cluster of craters produces a single-drained, irregular-shaped basin, or if flank erosion results in a quasiclosed depression. Under humid climates, craters and calderas degrade at a faster rate. Mostly at subtropical and tropical ocean-island and island-arc volcanoes, their erosion results in so-called amphitheater valleys that develop under heavy rainfall ( 1 F2500 mm/year), rainstorms, and high-elevation differences. Structural and lithological control, and groundwater in ocean islands, may in turn preform and guide development of high-energy valleys through rockfalls, landsliding, mudflows, and mass wasting. Given the intense erosion, amphitheater valleys are able to breach a primary depression from several directions and degrade the summit region at a high rate. Occasionally, amphitheater valleys may create summit depressions without a pre-existing crater or caldera. The resulting, negative landforms, which may drain in several directions and the primary origin of which is commonly unrecognizable, should be included in erosion-transformed volcanic depressions.

In the upper drainage basin of Mata Ri ver, a tributary of the Waiapu River, hilltop height accordances at two levels, 500-580 m and 560-640 m above sea level, are observed. Both hilltop height accordances are inferred to represent erosion surfaces developed over folded Neogene rocks. The lower erosion surface is estimated from geomorphological position relative to the Mangamaunu Upland and tephrochronology to have been formed during a period of25 000--30 000Received 24 March 1987, accepted 21 October 1987 years from prior to c. 35000 years ago to c. 12400 years ago (late Otiran). This lower erosion surface is not an elevated peneplain but was originally formed at a high level similar to its present altitude. The lower erosion surface was probably formed by cryoplanation under cooler and slightly drier climatic conditions than present with a sparse vegetation cover. The age of the higher erosion surface is not known but it must be much older than c. 35 000 years.

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The evolution of 84 volcanoes in the Philippines is outlined geomorphologically on the basis of interpretations of volcanic landforms using aerial photographs, topographic maps, satellite images, and geomorphological and geological field surveys. Fifty-six stratovolcanoes, three caldera, three lava domes, four scoria cones, four lava fields, and 10 shield volcanoes are identified. Large basaltic volcanoes such as lava fields and shield volcanoes were found unexpectedly in subduction zones. No lava field or shield volcano has been discovered on the Japanese Islands. Among the 34 subduction zones in the world, 19 do not have lava fields or shield volcanoes. Two oblique subduction zones form the Philippine Fault Zone. The fault zone mostly coincides with the eastern volcanic zone. At the southwestern part of Mindanao Island, a volcanic chain, consisting of Bulibu,

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The risk of artificial dam failure associated with volcaniclastic flows has been investigated. Hazardous volcanoes with a high possibility of imminent eruptions can be distinguished from other volcanoes by detailed studies of the last 10,000-year-eraption histories of the volcanoes in Japan. Most andesitic volcanoes in Japan have erupted periodically, once in 100 to 3000 years on average, and have sometimes generated volcaniclastic flows (pyroclastic flows, debris avalanches and debris flows) which have affected river channels. Many artificial dams have been constructed close to the hazardous volcanoes of Japan. The author has identified 17 danger zones with a high probability of occurrence of high magnitude floods related to artificial dam failure. Five of these danger zones are described in this paper. The most dangerous area extends across the lower Nobi alluvial plain, which concentrates a population of 2 million people. In the event of the Ontake volcano producing a large-scale pyroclastic flow or debris avalanche resulting in the failures of 18 artificial dams along the Kiso river, a torrential flood flow is predicted to cover the alluvial plain almost entirely, causing 10" to 105 human casualties in the process. The Yamba dam (with a capacity of 108-109 m3) along the Agatsuma river will be completed in 2006. The active Asama and Kusatsu-Shirane volcanoes are located in the headwater region of the drainage basin. Ten million people in Tokyo and the surrounding area live in the lower alluvial plain. Methods for monitoring community needs and perceptions, and research schemes for disaster prevention related to artificial dam failure should be urgently implemented.