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fern centered in a frozen pahoehoe swirl

Global Hawaii

Humuula Saddle—Between Giants


Overview

Nestled between the Big Island's two tallest volcanoes, Mauna Loa and Mauna Kea, the sparsely populated Humu'ula Saddle offers an excellent platform for the exploration of both. Hwy 200, otherwise known as the Saddle Road, connects  windward Hilo to the leeward Kona and Kohala districts, cresting at 6,500' near the Mauna Kea Recreation Area.

Most of the locals tried to discourage me from driving the Saddle Road. Bad road, they warned, not safe. Indeed the accident rate in the Saddle is higher than along other Big Island routes, so you'll need to drive with extra care and an eye on the weather. If you break down, run out of gas or hit dense fog, you could be stranded for quite a while, and you'd probably end up paying for road service out of pocket. But the route's no more challenging than any other curvy mountain road, and the visual rewards are well worth the ride all along the way.

Big Island shaded relief mapThings to see here include


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Saddle Gallery

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The first of a 2-frame panorama shows the east limb of Mauna Loa ("long mountain") looking south from a colorfully oxidized 3,000-year-old spatter rampart built by the oldest and farthest-flung of Mauna Loa's fissure vents. The axis of the rampart aligns roughly with Mauna Loa's summit. The bumps on the otherwise smooth east limb are the pyroclastic cones of Mauna Loa's northeast rift zone (NWRZ).

The Saddle Road makes a sharp jog south here along the rampart. Spent military bullet casings were everywhere underfoot at this site, just within the Pohakuloa Military Training Area. Alas, the repeated explosions I heard nearby were not volcanic.

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The west limb of Mauna Loa from the same vantage. Lacking a major rift zone, the west limb is much smoother than the east.

My freebie panorama stitching software QuickStitch wouldn't line up Mauna Loa correctly. Maybe yours will.

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The out-of-this-world candy selection at the Onizuka Center for International Astronomy Visitor Information Station at 9,300' on the Mauna Kea Road.
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The lower tier of the Mauna Kea ("white mountain") summit complex, looking NW from the upper tier. Left to right are the recently inaugurated Subaru 8.2 m single-mirror optical telescope, the Keck I and II multi-mirror visible and infrared pair and the NASA Infrared Telescope, all atop an oxidized cinder cone of Mauna Kea's capping stage.

On the horizon across the Alenuihaha Channel is Maui's youngest volcano, Haleakala ("house of the sun", 10,025 ft), last active in 1790. Now 225 km NW of the hot spot, Haleakala is 100,000 years into its post-erosional stage of rejuvenated and usually explosive volcanism.

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The largest of the upper-tier observatories at the true summit, here looking north.

The friendly construction workers I encountered nearby drive up to the summit (13,796 ft) daily from homes at or near sea level. I'm short of breath just walking around up here, and they're doing heavy labor. What an unusual physiology they must have developed on this job!

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Pu'u Poliahu ("hill of the snow goddess"), a capping phase cinder cone with its summit and crater intact. The cone's asymmetry reflects the direction of the prevailing northeasterly tradewinds.

In the distance to the WSW is Kona's Hualalai volcano (8,271 ft), also in the capping stage. Many cones just like Pu'u Poliahu here rough up its profile.

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The majesty of Mauna Loa, looking south. Dark flows of 1843-1942 vintage have dripped down from the NERZ.

The semi-circular ridge in the middle ground is a glacial moraine from the Wisconsinan ice age. Glaciers last covered the summit about 20,000 years ago.

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To maintain the thermal stability of the mirrors and instruments, Keck visitors are restricted to this small glassed-in viewing area beneath Keck I. It's hard to convince yourself you're looking at a telescope through all the steel girders and cables. The only thing I could tell for sure was that this was all very expensive.
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The entire Mauna Kea summit complex, now looking back to the east from Pu'u Poliahu. At this altitude, you're above 60% of the atmosphere, which is great for seeing but so-so for breathing.

The volcanic bombs littering the foreground slope of cinder testify to the explosive nature of capping phase alkalic eruptions. Such pyroclastics cover most of the summit area. Exposed flows like the one to the right of the small silver dome are the rule on Mauna Loa and Kilauea but are uncommon up here.

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Looking NW from Mauna Kea's summit in the direction of Pacific Plate motion relative to the hot spot, Maui's Haleakala volcano dominates the horizon. Directly in line between these two giants and barely visible through the clouds is the summit of Hawaii's oldest shield volcano, Kohala (5505 ft), last active 400,000 years ago and now in its final erosional phase.
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Is there an emergency evacuation vehicle where you work? The dome houses a radio telescope.

Hundred mile an hour winds, blizzards that last for days, UV radiation you can feel, 4,000-year-old cinder cones that probably won't explode again, the world's largest active volcano for a neighbor—what's to worry?

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Subaru—built and owned by the Japanese government, not the car maker—is to the left of this light pollution control sign; the Kecks are on the right. "Subaru" is the Japanese name for the beautiful open cluster in Taurus we call the Pleiades.
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Big holes cut to appease the wind didn't save this sign from a backbend. Believe both messages.
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This is the first shot of a 5-frame low resolution (640x480) 135 panoramic sweep from northeast to south, taken a little below Mauna Kea's summit.
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With oxidized cinder cones and tephra dominating the highest reaches of Mauna Kea, everything looks rusty. Mauna Kea means "white mountain", no doubt for its frequent snow cap, but "red top" would have been another good choice. This coloration is evident even at a distance.
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An oxidized capping phase cinder cone capping Mauna Kea.
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Ever-present clouds lap onto the windward coast at the foot of Mauna Loa. Hilo, socked in as usual, is behind the cinder cone at left.
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Looking south now, Mauna Loa's Mokuaweoweo Caldera is visible at the summit. At 4 km wide and 180 m deep, the caldera is similar in area to Kilauea's but not as deep.
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Now a high resolution (1280x960) version of the same 5-frame 135 panoramic sweep from a slightly different vantage.
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Similar to sad16.jpg.
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Similar to sad19.jpg—my best shot yet of the Mokuaweoweo Caldera at Mauna Loa's summit.
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This 2-frame panorama shows the eastern half of the Humuula saddle. Unfortunately, the photo doesn't do justice to the beautiful deep reds and greens of the forested lower Mauna Kea cinder cone at left center.
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The cinder cones in the saddle here all belong to Mauna Kea. Might they reflect passage of the hot spot and the transfer of the torch to Mauna Loa?
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Tilted beds of black lapilli (pea-sized cinders) below the Mauna Kea summit.
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More colorful pyroclastic beds further down the road. Note the discrete red bake zone formed when the dark gray rubbly a'a flow overran the pale red pyroclastics at road's edge. The deep weathering of the a'a reflects the extreme climate here and the 4,000+ year age of the flow. Compare, for example with the ca. 1970 Mauna Ulu a'a flow seen in nap16.jpg on the Napau Crater Trail page.
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A 2-part low resolution panoramic sweep of Mauna Kea looking north from the foot of Mauna Loa, just above the Saddle.
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The weathered a'a in the foreground is probably prehistoric.
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Endless pahoehoe from a Mauna Loa flow (1899?) stretching to the horizon, here looking upslope to the southwest. Distant cones dot horizon along Mauna Loa's NERZ.
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The same pahoehoe flow, now looking downslope and northeast to the saddle.
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This 8-10 m tube skylight well down a pahoehoe flow (1899?) at the foot of Mauna Loa looks to me like it hosted a fountaining breakout at one point. Note the drainback glazing at the lips and the spatter ramparts beyond.
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A close-up of the same skylight.
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An even smaller breakout nearby, less than 1 m across and at least 2 m deep. Presumed cooling cracks form a polygonal pattern on the drainback surface at bottom.
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Mauna Kea's north flank, this time at low resolution. Oxidized tephra from capping phase eruptions impart the reddish color at the top.

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Please address comments and corrections to jeremy@cliffshade.com

2002 Jeremy McCreary; last updated January 21, 2006

URL http://www.cliffshade.com/hawaii/saddle/index.htm