OHE January 5, 1999 (Diamond Head Rim)

Date: Tue, 5 Jan 1999 22:02:16 -1000
From: "Kirby D. Young" (kirbyd@teleport.com>
Subject: Diamond Head rim, 8-Dec-98

Sorry this is a bit old....

My route for this hike was simple. Complete a circuit of Diamond Head rim beginning above the public tunnel entrance, walking counter-clockwise. The story:

I decided to take a much-needed late afternoon break from some writing work I was doing, so drove to Diamond Head crater, where I passed through the tunnel and parked at the trailhead lot around 3:45 PM. My plan was to walk counter-clockwise around the rim of Diamond Head, rather than ascend to the Leahi summit by the usual trail.

Leaving my car I walked back towards the tunnel, where I ascended a rubbly eroded path I'd spotted just to the right of the tunnel entrance. I took care not to slip or dislodge any loose rocks that might roll onto the road (it may be protected by a fence from this, however, I forget). Loose rubble awaited me like ball bearings on the inward-dipping layers of volcanic tuff that make up Diamond Head. While the tuff beds are generally brownish, there were many white fragments weathering out from the rock here. Most of these are coming from crack-filling veins of calcite and zeolites. While Diamond Head is named for diamond-like crystals of calcite found on it more than a century ago, the only calcite (and zeolites) I would see today would be very opaque white, grungy-looking varieties. Another source of white rocks on Diamond Head is chunks of limestone ripped up as the eruption that formed this large crater blasted its way through the coral reef of the time.

Arriving at a service road just before the rim, I turned right to find a path of least resistance to reach the top. Beginning my ccw journey at about 4 PM, I quickly had a look down onto the outside tunnel entrance I'd driven through minutes before.

From that point, the walking was remarkably easy on the nearly level, broad crater rim. I passed a number of communications (?) facilities of various kinds, as well as cables, PVC pipes, and the like. In spite of it being a very cloudy day, views of the rain-shrouded Koolaus and much of Honolulu were outstanding. After traversing about 1/4 of the crater circumference, I neared the end of the level section. I was surprised how oddly small the long stairways on the main Trail looked from this vantage point. Diamond Head is really a relatively large feature! It is this wide separation of opposing rims across a flat crater floor that leads most geologists to refer to it as a "tuff ring", part of a spectrum of volcanic features formed by the explosive interaction of rising magma and water.

The rim ascent of several hundred feet to the Leahi summit is narrow in places, with significant vertical drops of 50-200' on the outside. While the slopes on the crater side are also very steep in places, it seemed that almost everywhere there was the option of choosing a lower route with less exposure on that side, when needed. Some rock scrambling where the rim rose up steeply was required or when transitioning between a lower and rim-top route. At one point in my climb, I paused to look face-on across a small valley inside the crater to the switchbacks of the regular trail. There were many hikers on it, and I found their back and forth switchback movements to be slightly hypnotic.

Refocusing on my rim walk, I soon reached a small summit with a bunker just short of the top. Here I paused to look at the great view of Waikiki, Kapiolani Park, the Ala Wai, and Honolulu. I didn't plan on stopping at the true summit because of the cast of constantly changing "1000" hikers already there.

Facing the _strong_ trades gave me an appreciation for how similar winds at the time of the Diamond Head eruption had pushed the airborne ash and "lapilli" (like ash, but pebble size) to the downwind side, forming this pronounced summit on the crater rim. In the distance I could see the similarly asymmetric Koko Crater, its smaller diameter but higher rim of ash and cinder layers forming, not a "ring", but a "tuff cone".

While younger than Koolau volcano, Diamond Head is still no spring chicken, having erupted many tens of thousands of years ago as part of the sporadic "rejuvenated" Oahu volcanism. It lies at the south end of a line of eruption centers that includes Kaimuki (a large lava shield) and lava-floored Ka'au Crater.

Past the summit I began the somewhat steep descent to a low point in the rim. Loose rocks in this stretch were surprisingly treacherous, and maybe more hazardous than the narrow and exposed sections of my ascent! There were many calcite and/or zeolite veins crisscrossing the tuff here.

Bottoming out, I then climbed steeply up and over a rim summit with a prominent bunker. Views of Kahala district and lavish Black Point (lava flow erupted during "rejuvenated" volcanism), rewarded me here. Near a low point in the rim beyond I recognized a route I'd cajoled a friend to accompany me on a climb up the outside several years ago. This corresponds to Wing Ng's Diamond Head ridge route #9.

Passing the very lowest elevation point in the rim, I noticed a number of cars parked at a bunker entrance on the inner side of the crater rim. Several left in the next several minutes as it presumably was "quittin' time". Quittin' what, I don't know.

The final quarter mile returned to easy, fairly level rim walking with a short incline near the end. I arrived at the tunnel overlook about 1 hr 10 min after I began my circuit.

Deciding it would be easier to descend via the outside slope of the crater here, I followed an obvious path down towards an overlook at the tunnel entrance. In places there were convenient steps of sorts. It was a far better route than the one I had taken up. In short order I was at the road, which I followed through the tunnel and into the crater to return to my car. I hugged the tunnel wall respectfully at one point as a trolley bus drove past.

I then drove home and got back to work (sigh).

Kirby

Note: While I encountered no problems, a previous OHE post by Dayle Turner (11/97) mentioned that the authorities do not necessarily take kindly to hikers doing this circuit.


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