OHE December 27, 1998 (Makiki-Tantalus)

Date: Sun, 27 Dec 1998 11:05:25 -1000
From: "Kirby D. Young" (kirbyd@teleport.com>
Subject: Makiki-Tantalus CCW version 12-2-98

Makiki/Tantalus - Wednesday - Dec. 2 1998
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(Procrastinated finishing this for about a week. Dayle's recent entertaining post about this hiking loop reminded me to get it done!)

I had yet to ever do the Makiki valley portions of this loop hike and, because clouds and rain were obscuring the higher elevations of the Koolaus, I decided to take on this well known loop. My itinerary: Maunalaha and Moleka Trails up, Manoa Cliffs Trail 1/2 ccw, side loop trip cw around the Tantalus summit crater, continue Manoa Cliffs Tr. ccw to Tantalus Dr., descent on Nahuina and Kanealole Trails to car. Along the way I enjoyed windy views, wild alternations of rain and sun, and looked at a little of the geology. The (too long?) story:

I Arrived at the Makiki Nature Center about 10 am, and parallel-parked along the road. A steady stream of parents with children were arriving (dropoffs for day-care?). Walked 100 yds up the road, then turned right to pass several mobile trailers before lingering at a large raised-relief map of the Makiki/Tantalus area sheltered in a small kiosk (very nice). Proceeded over Moleka Stream on a short footbridge, then began my ascent on the Maunalaha Trail which, after 2 switchbacks and an uphill traverse, reached the crest of a small ridge. Rain competed with sun in the next 5 minutes as I walked along this ascending buttress. I was a little dismayed to see the ridge top completely consumed by the wide, very rooted trail. During this stretch, I played hiker tag with two Japanese women as I fussed with my camcorder between spurts of rain. As the ridge angled up more steeply the trail contoured right, exposing numerous pahoehoe flows in cross section. One very distinct tractor tread-like fold in the flow layering caught my eye.

As the ridge leveled off, the trail did an elevation "catch-up", bringing me to a 4-spoked junction of paths. Several hikers were doing a standing rest at this well-signed location. I selected the trail spoke contouring upwards and right, and after 1/4 mile arrived at a junction with the Moleka Trail. Making the sharp left at this junction, I contoured up along the Makiki-facing side of Pu'u Kakea. Deep forest soon yielded to open views of several estates at the head of Makiki Valley. At the same time, muddy trail conditions gave way to a cindery surface of pea-sized black volcanic tephra ("tephra" = volcanic fragments that fall from the air after being erupted). Nearby trail cuts into the hillside exposed steeply inclined layers of these cinders which had been erupted from Pu'u Kakea (Sugarloaf), one of three volcanic vents in the Tantalus area. The other vents are Pu'u Ohia (Tantalus) and Pu'u Ualaka'a (Roundtop). Besides forming cinder cones on the tops of the high eroded ridges ewa of Manoa Valley, Pu'u Ohia and Pu'u Kakea erupted notable lava flows as well. They are part of the many "rejuvenated" sites of volcanism that popped up in eastern Oahu long after the main Ko'olau shield volcano became extinct. As best as can be determined, these 3 volcanic cones are the _youngest_ of the many "rejunenated stage" cones and craters dotting Oahu. Their most recent eruption may have occurred less than 10,000 years ago! (That's recent, really! Main Ko'olau shield volcano became extinct something like 1.5 million years ago).

As I continued contouring along the curving slope of Pu'u Kakea, the trail entered a densely-forested side valley. Here there were fist-sized cindery bombs of lava hanging rather loosely in a low cut by the trail. I must have passed close to the eruptive vent along this section.

Heavy rain began, persisting for about 5-10 minutes as I made my way on through a bamboo forest, across Tantalus Drive, and onto the Manoa Cliffs Trail. After several minutes walking uphill, I crossed the Makiki/Manoa divide and dropped briefly to begin the spectacular contour along the upper valley sidewall with Manoa Valley 1000' below on my right. Ahead, the Ko'olau crest was completely immersed in clouds and rain. Luckily, the rain and mists gave way frequently to a bit of sun, revealing narrow Ko'olau ridges descending out of thick clouds.

At an especially prominent point after about 1 mile of contouring, a bench was available for admiring great views that had expanded to include Pauoa Flats, Nuuanu overlook, the head of Nuuanu Valley, and a small slice of windward Oahu. Cloud bottoms scraped not that far above the Nuuanu Pali area, and with the tradewinds roaring at 25-45 mph, the scraping was happening real fast. In the back of Manoa Valley, a very significant ribbon of water was descending one of the headwall valleys. What surprised me was that, as best I could make out from the topo map, this waterfall was one valley right of well-known Manoa Falls.

More heavy rain accompanied me to a junction with the Pu'u Ohia Trail. Staying left, I followed the latter route upwards, first contouring, then directly assaulting the mauka summit of Tantalus through a youthful bamboo forest. Strong winds caused a disconcerting clacking and bending of bamboo-against-bamboo with each powerful gust. Arriving at the top, I encountered an e.m. relay station of some sort at the end of a paved service road.

Turning left past the station, I reentered the bamboo forest on a narrow trail. I didn't know its destination, but I gambled it would lead along the Manoa rim of Tantalus crater to its makai summit. (A service road follows the Pauoa-side rim). Following a steep descent, I climbed to an intermediate summit. From here I had a good view down onto the Manoa Cliffs Trail where it rounded a small projecting ridge. Also clearly visible was my ultimate objective, the makai summit of Tantalus. Descending into the second gap, the trail followed several engineered switchbacks (!), crossed another low point of the crater rim in dark bamboo forest, then rose gradually, soon coming to the main trail.

A right turn, 70 yds walking to the service road, left turn and 50 yds uphill walking led me to the final few feet of climbing by a short trail to the highest point. A cement foundation here provided a nice pedestal to check out the 360 deg views in (I don't believe it) full sunshine (at least where I was).

After enjoying lunch, I backtracked downhill along the service road, following it all the way back to the mauka summit (sun), thus completing a loop around Tantalus crater rim. I then descended the Pu'u Ohia Trail (cloudy), joined the Manoa Cliffs Trail, and proceeded to continue my ccw traverse on it. Quickly passed a junction with the Pauoa Flats trail (heavy rain), then descended in several switchbacks to a junction with a Pauoa Flats cutoff route called the Kalawahine Trail (rain+sun).

Contouring makai with Pauoa Valley on my right, I noticed the Nuuanu Trail cutting across a slope opposite me towards Pauoa Flats. Passing an area of large boulders, half covered by the dense vegetation, I pondered their origin, then decided I didn't have a clue. Later, I speculated maybe they were erosional or collapsed remnants of the large lava flow that erupted from Tantalus. This flow ponded at the head of Pauoa Valley, supposedly to a thickness as great as 500' (what?!) before it descended that valley some distance. The surface of the ponded portion of this lava flow created Pauoa Flats.

Contouring further, the trail switched from the muddy/slippery surface typically developed on the rain-soaked remnants of Ko'olau shield lavas to more pea-sized cinders. These no doubt were erupted from Pu'u Ohia (i.e. Tantalus), as I was on its steep Pauoa-side flank. Not only were the cinders the sizes of large peas, they were smoothly rounded like peas in some places, giving the trail surface an odd look. The idea about such balls of lava is that they repeatedly fell back into the vent to be milled and rounded. Eventually a large enough explosion sent them onto the flank of the Pu'u Ohia cone. Steeply-dipping layers of this volcanically-erupted material were were exposed by a trail cut nearby.

In most places, of course, thick rain-soaked vegetation obscured whatever bedrock lay beneath. Occasional views down Pauoa Valley towards the Airport and Pearl Harbor kept my head turning slightly right to enjoy the scenes. Rain totally obscured the Waianaes.

Finishing my Manoa Trail traverse with a bit of upward contouring I arrived at Tantalus Drive. After proceeding a short way makai on a level portion of the road, I re-entered the forest on the Nahuina Trail on the Makiki valley side (left). Descended several switchbacks in rain (after sun on the road), passing a _very_ rural looking local guy near the valley bottom. Connecting to the wide and very wet Kanealole Trail, I descended the final mile or so to the trailhead and my parked car (sunny again), arriving about 4.5 hours after I began my journey.

Addendum: General comments I've made here on the geology of the Tantalus area are based almost entirely on information in the handsome and elegant book "Volcanoes in the Sea - The Geology of Hawaii" by G. A. Macdonald and A. T. Abbott, 1970, Univ. Hawaii Press. Currently there is a 2nd edtion, 1983, which is well worth owning for anyone interested in Hawaiian geology!

Happy holidays from the Mainland (aka Rainland)

Kirby


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