{{Short description|Remains of ancient Hawaiian volcano}} {{Use American English|date=February 2026}} {{Use mdy dates|date=January 2025}} {{More citations needed|date=March 2013}} {{Infobox mountain | name = Wai{{okina}}anae Range | other_name = | image = Oahu-Kukaniloko-shape-of-Waianaes.JPG | image_caption = View of the Waianae Range | elevation_ft = 4025 | elevation_ref = | prominence_ft = 4025 | prominence_ref = <br /><small>HP of Oahu</small> | map = Hawaii | map_caption = | label_position = left | listing = | location = Oahu, Hawaii, U.S. | range = Hawaiian Islands | coordinates = {{coord|21|30|36|N|158|9|0|W|type:mountain_region:US-HI_scale:100000|format=dms|display=inline,title}} | range_coordinates = | coordinates_ref = | topo = USGS Kilohana (HI) | type = Extinct shield volcano | age = 3.9 Ma | volcanic_zone = Hawaiian-Emperor seamount chain | last_eruption = 2.5 Ma | first_ascent = | easiest_route = trail }}
'''Wai{{Okina}}anae Range''' (sometimes referred to as the ''Waianae Mountains'') is the eroded remains of an ancient shield volcano that comprises the western half of the Hawaiian Island of O{{Okina}}ahu.<ref>{{cite web|last=Rubin|first=Ken|title=Waianae Volcano|date=11 July 1998|url=http://www.soest.hawaii.edu/GG/HCV/waianae.html|publisher=Hawaii Center for Volcanology|access-date=23 July 2010|author2=Brandon Doo }}</ref> Its crest, at Kaʻala, is the highest peak on O{{Okina}}ahu at {{convert|4025|ft|m|0}}.
Like the neighboring Ko{{Okina}}olau, the Wai{{Okina}}anae Range is not a mountain range in the sense most people are familiar with, as the mountain range as a whole was created from a single volcano rather than plate tectonics.
The oldest lava dated from the volcano are about 3.9 million years old. About 3.2 million years ago, the volcano's activity changed, the rate of eruption started to decrease and the composition of the lava erupted from the volcano changed. The volcano is thought to have last erupted about 2.5 million years ago.
When active, the Wai{{Okina}}anae volcano's center of activity was at present-day Lualualei Valley. Intense erosion on the western flank of the mountain has destroyed much of those flanks. Thus, the mountain today is much smaller than it was when the volcano was active.
While the western part of the mountain has been destroyed by erosion, the eastern part is still in a youthful stage of erosion. This is considered somewhat strange by some geologists since the western part of the volcano is on the leeward side of the island; thus, most rain falls on the eastern side of the volcano. Given this information, more erosion would be expected on the eastern portion of the mountain. One theory to explain this erosion pattern is that a large landslide cut away the western portion of the volcano. The faults from this huge landslide weakened the rock, making the western part of the mountain much more susceptible to erosion than the eastern side.
==References== {{reflist}}
==External links== *{{cite gvp|name=Waianae|vn=332808|access-date=2021-06-28}}
{{Hawaiian volcanism}}
Category:Waianae Range Category:Volcanoes of Oahu Category:Extinct volcanoes of the United States Category:Mountains of Hawaii Category:Landforms of Oahu Category:Polygenetic shield volcanoes Category:Hawaiian–Emperor seamount chain Category:Pliocene shield volcanoes Category:Pleistocene shield volcanoes Category:Neogene Oceania Category:Cenozoic Hawaii