The Ewa Plain Karst is the largest of several karsts on the island of Oahu
Yet one of the least known! (The reason: Ewa developers oppose studies)
Anne Wiley, Michigan State University doctoral student, left, and Andreanna Welch, doctoral student at the University of Maryland, look around in an Ewa sinkhole
Despite its impressive extent and archaeological and palaeontological values, the Ewa Karst is almost entirely unknown to karstographers and speleologists.
(Pre-printed from The Cave Conservationist - February 1998)
The Ewa Karst is the largest of several karsts on the well-populated island of Oahu, yet one of the least known (Halliday, 1994). Its exact dimensions are uncertain because geological maps show considerable upslope areas as alluvium and some shore areas as sand.
However it clearly covers at least 50 km2 in the southwest corner of the island of Oahu (Figure 1). It is a semitropical littoral karst formed on porous, permeable algal and coralline reef deposits formed during at least three high stands of sea level (Figure 2), perhaps with a higher content of sand-sized clasts of foraminifera than contemporaneous Caribbean deposits (Chester Lao, written communication, 1997).
Some artesian flow is said to be present, confined by clay layers (Chester Lao, oral communication, 1997). The U.S. Geological Survey Ewa Quadrangle shows numerous sinking streams and closed depressions within the Karst. Some of the former are artificial: the result of past water diversion for farming, ranching and domestic use. Some of the depressions are man made also. Most of the land surface of the karst has been subjected to more than a century of extensive reworking by man.
In 1955, the late Harold S. Palmer (Professor of Geology at the University of Hawaii) told me he had seen a meter-long stalactite said to have come from a cave in the Ewa Karst (Halliday, 1955, 1958). Extensive bibliographic and some field investigations have yielded no information about this cave and it is not known if it still exists. In 1970, Macdonald and Ahhott mentioned the presence of small caves in calcarenite and aeolianite in this and several other karstic localities (Macdonald and Abbott, 1970) but did not amplify.
Sinkholes of Kalaeloa
by Nate Yuen | Mar 29, 2009
I explored the kiawe forests of Kalaeloa — the former Barber’s Point Naval Air Station — to investigate the innumerable sinkholes in the limestone that were once home to rare native land snails.
Limestone, the remnants of coral reefs when the sea level was higher, underlies the greater part of Kalaeloa and the Ewa Plain. Located in the rain shadow of the Koolau and Waianae Mountains, Kalaeloa is located in the driest corner of Oahu, receiving less than 20 inches of rain per year. While the surface of the land is dry and hot for most of the year, just below the surface lies ground water which seeps from the mountains under the Ewa Plain.
Beacons from the Ewa Plains
September 22, 2012http://studiamirabilium.com/2012/09/22/beacons-from-the-ewa-plains/
Not too many people think of the natural wonders of Hawai’i when they see the Ewa Plains. The present is dominant by such thoughts as commute times, median home prices, proximity to good schools. People do think of its rich past: many extinct native birds have been found fossilized in the uplifted limestone plains. But it’s these wonderful plants, an akoko here, a rare naio there, that offer beacons of hope for a great future.
