WINDWARD WATERSHEDS
Ko`olauloa

The windward coast ....lies along the northeastern shores and inland valleys of the younger of the two volcanic masses which later joined to form the island of Oahu. This younger mass, known to geologists as the Ko`olau Volcano, gradually built its ridge in a northwesterly direction and began to fill in the ocean space which separated it from the dying Wai`anae Volcano to the westward. As the Ko`olau flows continued, the two mountain masses were joined and "what is now called the [central] Schofield Plateau resulted from the Koolau flows banking against the Waianae Mountain" (Stearns, 1939, p. 9). Thereafter active vulcanism ceased in the original firepits, and streams originating where the high peaks and cliffs caught the rain carved out great valleys on both the windward and leeward faces of the Ko`olau range. "Meanwhile the streams of the [older] Waianae Range had nearly dried up because the moist northeast trades were cut off by the growth of the Koolau Volcano" (Stearns, 1939, p. 9). Thus the fundamental characters of windward and leeward Oahu became fixed, from the point of view of the planter who was to dwell on the island millenia later.

The physical features of valley and shore line were to be greatly altered before the era of human habitation began. Great episodes of submergence and re-emergence of valley bottoms by and from the ocean occurred, during which new bays appeared across drowned valleys, valley heads became sea cliffs, and coral reefs became elevated sections of shore line. Later the upheaval of new cones and peaks and offshore islets further changed the topography.(1)

Numerous trails provide access to the more remote, mauka parts of Ko`olauloa. Descriptions of these, including in some cases, photographs and personal experiences, are provided on web pages maintained by hiking clubs on O`ahu. Try these:

Ahupua`a of the Watershed Ring
  • Ka`a`awa
  • Kahana
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    SOURCES: (1) E. S. C. Handy, E. G. Handy, and Mary Pukui. 1972. Native Planters in Old Hawaii. Their Life, Lore, and Environment, Bernice P. Bishop Museum Bulletin 233: p. 434-435
         Stearns, Harold T. 1939. Geologic Map and Guide of the Island of Oahu, Hawaii.
          Div. Hydrography, Territory of Hawaii, Bull. 2. Honolulu

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