zone, which was weakened by the collapse. As the dikes forced their way up, they formed fractures and faults parallel to the rift zone. The exertion caused by the dikes produced a series of faults along its length, forming horsts and grabens (fault blocks). Northeast of the Kohala summit, where the most rainfall occurs, the faulted structure prevents summit rainwater from naturally flowing northeast down the mountain slope. Instead, the rainwater flows down laterally and empties into the back of what have thus become the largest valleys (Waipio and Honokane Nui). The leeward northwestern slope of Kohala has few stream valleys cut into it, the result of the rain shadow effect, as the dominant trade winds bring most of the rainfall to the northeastern slope of the volcano. The seven windward valleys of Kohala are, from southeast to northwest, Waipio, Waimanu, Honopue, Honokea, Honokane Iki, Honokane Nui, and Pololu. The size of the valleys reflects the amount of drainage they have been able to capture; Waipio, the largest, at some point drained Waimanu Valley as well, and the former headwaters of Waimanu are now one of its branches. Waimanu valley, cut off from its headwaters to the summit and left with Wai'ilikahi as its main tributary, still had managed to form a substantial floodplain, although less than half the size of Waipio. Honokane Nui, the third largest valley, has its drainage almost exclusively from the north side of the summit, and as a result is a deep, long, narrow bottomed valley with little habitable floodplain. The remaining valleys derive all their water from the lower northeastern slopes of the volcano, and as a result are smaller. In addition, there are innumerable gulches of various depths which have not yet reached sea level and began to form flood plains, becoming valleys. Still, some of these are more than in depth. The depth of the actual valley walls at the seashore range from at the Waipio Valley Lookout at the southeastern corner of Kohala mountain, to a high of over in Honopue, then diminishing to less than at Pololu Lookout at the northern end of the valleys. In the back, deeper in the mountain, all of the valleys have sheer walls well in excess of . Numerous spectacular waterfalls cascade or fall over these cliffs. Some, such as Hi'ilawe Falls in Waipi'o valley, have single drops exceeding . The volcano stayed active