Friday, July 22, 2016

The Hawai'i That Was: A Veritable Rainbow of Sand (and cute gratuitous sea turtles)

Lai'e Beach on the island of Oahu, with a coral beach sand stained by iron oxides
Sand is white or gray. If you live in Florida or some other low-lying coastline, the sand tends to be nearly pure quartz, leading to the white color. In California and other mountainous coasts, there are other minerals mixed with the quartz, leading to a grayer shade. But there is something different about sand on the Hawaiian Islands. There is hardly a trace of quartz to be found, so the sandy beaches are made of other things. As a result, beaches in Hawai'i can be red, white, yellow, gray, black...and green.

The ocean is relentless. Waves are generated in storms all over the Pacific Ocean basin, and the energy is expended against of the shores of the Hawaiian archipelago. Whatever is there is going to be disintegrated into small particles. Much of the time, two kinds of rock face the waves. Basalt lava flows, and coral reefs. Where does all the color come from?
Coral sand on the south shore of Kaua'i (can you see any camouflaged creatures?)

Corals can be colorful when alive, but bereft of living cells, the reef is usually white. The sand that results from waves pounding on the margins of the reefs is therefore usually white as well (Parrotfish also chew up the coral, making sand particles). Basalt is black, but the minerals that make up basalt are high in iron, so when the rocks weather, reddish iron oxides are produced that can stain the fragments of coral to produce reddish or yellowish sands, like those seen above, from the south shore of Kaua'i. 
Kalapana-area lava flow reaching the sea in 2009, from vents seven miles away at Pu'u O'o.

On the younger coastlines of the Big Island, sand forms in a different way. Lava flows reaching the shoreline can have explosive reactions when encountering the water. The lava shatters into small sand-sized particles, forming black sand beaches. Such beaches will disappear in time, and are thus uncommon. The most accessible beach is Punalu'u on the south side of the Big Island. We paid a visit during our recent exploration.

Punalu'u Beach is a pretty stretch of coast backed by coconut trees, with a seaward projection of lava provides some protection from the worst of the wave action. That makes it a great recreational beach, but also an excellent habitat for Green Sea Turtles (Chelonia myda).
The beach provides a resting area for the turtles, and the calm water just offshore provides extensive growths of algae that they prefer to feed on. They don't breed here, though. Most of the turtles in Hawai'i nest on the French Frigate Shoals several hundred miles to the northwest.
The turtles, honu to the native Hawaiians, were both revered but also used in a number of ways, for food, medicine, and tools. They were doing well enough until the Europeans arrived and started using them for food as well. Their population went into a steep decline until they gained legal protection in 1978. Their numbers have rebounded somewhat in the years since, although they are still considered endangered.

It's a serious thing that turtles and people share a popular beach. It's far to easy to harass and injure the slow moving turtles, and tourists can be real jerks at times. Volunteers are often around to protect the turtles and provide some education. If my pictures seem to have been taken from way too close, remember I have a zoom lens! I can be a jerk at times, but not with these beautiful creatures.

The most unique sand one can find in the Hawaiian Islands is the green kind. These sands are composed of olivine (also known as the gemstone peridot). Olivine is a major constituent of basalt all over the islands, but it weathers rapidly into iron oxide and clay under normal conditions. One can almost always find a few bits of olivine on any gray or black sand beach, but a green beach is a true rarity.
Papalokea Beach (also creatively known as Green Sand Beach) can be found a few miles northeast of South Point on the Big Island. Around 50,000 years ago, an eruption produced a cinder cone of loosely aggregated cinders and smaller fragments. It was rich in olivine crystals, and as waves attack the cliff, the small gems are released immediately onto the beach. There simply isn't enough time for them to weather away like they do elsewhere.

Most of my students made the five mile trek out and back to see the beach. I didn't make it this trip, but I did the hike in 2009 and got these pictures. Walking across a hot, windy, arid coastal plain might not sound like an exciting journey, but the destination is clearly spectacular, and the road passes numerous archaeological ruins. This empty coastline was home to many native Hawaiians who fished the waters offshore.
We had spent four days exploring Hawai'i Volcanoes National Park and the vicinity, but we were now headed around the island towards the Kona Coast and Kohala. We were about to see a completely different aspect of the Hawaiian Islands.

"The Hawai'i That Was" is an ongoing series that is exploring the Hawaiian Islands as they existed in the years prior to the arrival of humans on the island, and the changes that have occurred since then.

Wednesday, July 20, 2016

The Hawai'i That Was: Where are the Rivers? Waterfalls on the Big Island


Tooling around on the southern parts of the Big Island of Hawai'i, one may notice something. Despite the fact that Hilo and the Puna District villages get more rain than any other towns in the United States, there aren't very many rivers. The area is a rainforest, but there are hardly any areas of open water. In fact, a drive around the most of the island, say from Hawi on the north end through Kailua-Kona, around South Point and along the slopes of Mauna Loa and Kilauea, I can't recall seeing a single flow of water. There are a number of reasons. For one, some areas lie in the rain shadow of the big volcanoes. The area north of Kona is practically a desert. On the slopes of Mauna Loa and Kilauea, the reason has to do with the volcanoes themselves.
Wailuku River from the top of Rainbow Falls
Basalt lava, the product of Hawai'i's volcanoes, is not a particularly permeable rock. There might be vesicles (gas bubbles) that can allow water to move through, but by and large basalt is solid and impermeable. Except when it cools. The rock contracts and shrinks, forming joints and fractures. These cracks provide avenues for water to sink into the ground. There might be plenty of water, but it flows through subterranean fissures, not on the surface. It might re-emerge along the coastline as springs, but in some cases the water flows into the ocean beneath sea level. There are places along the south coast of the Big Island where the only fresh water could be collected by the original Hawaiians by diving beneath the surf with water containers.
Rainbow Falls in Hilo,
The longest river in the Hawaiian Islands is the Wailuku, which runs for 28 miles mostly along the boundary between the lavas of Mauna Kea and Mauna Loa, then flowing into Hilo Bay. Although large volumes of water disappear underground, the path of the river partly follows much older Mauna Kea lavas that have weathered and form soil and clay that are more impermeable, keeping the water at the surface. In places, erosion has broken through to breccias and cinder layers that are more easily eroded, undercutting the lava flows. In this way, some beautiful waterfalls have formed. The most famous is undoubtedly Rainbow Falls (above), given the location near downtown Hilo.

The falls, known in the Hawaiian language as Waianuenue, are steeped in mythology. Stories have grown around the prominent cave behind the falls. It was the abode of Hina, the mother of Maui, the god who created the islands by tricking his brothers into pulling up part of the seafloor, thinking they were hauling in giant fish. A lizard-like monster called Mo`o Kuna kept threatening Hina by sending floods and debris down the river (floods are a common occurrence along the river). Maui came to the aid of his mother, defeating Mo'o Kuna and sending his carcass down the river.
Pe'epe'e Falls on the Wailuku River upstream of Hilo

Pe'epe'e Falls are a short distance upstream, and Wai'ale Falls can be seen a bit further up. Wai'ale tends to have the greater volume as water seeps into the ground downstream.
Wai'ale Falls on the Waikulu River near Hilo
On the Big Island of Hawai'i, the real world of waterfalls lies along the northeast coast between Hilo and the Polulu Valley. They occur on the flanks of Mauna Kea and Kohala, two of the older and mostly inactive volcanoes of the island. Some of the falls are world class in height, with at least one, Waihilau, falling 2,600 feet, which is actually taller than Yosemite Falls in California. I would love to regale you with stories of my adventures seeking out the giant falls in their remote valleys, but I haven't done that yet. We'll settle for a beautiful and accessible waterfall north of Hilo. It's called Akaka Falls, which drops about 420 feet. There is a short paved trail that provides a dramatic view.
This blog series, the Hawai'i That Was, is an exploration of the geology and anthropology of the islands, based loosely on our recently completed field course. I expect that the next post will be a bit sandy...and crawling with turtles. Stay tuned!

Tuesday, July 19, 2016

The Hawai'i That Was: There was a Monster in the Water at Laupahoehoe

There is a small bay a few miles northwest of Hilo on the Big Island of Hawai'i called Laupahoehoe. It's a raw section of the coastline, with waves that crash violently against the ragged exposures of basalt. I stand at the point and imagine the movies I've seen where monsters rise out of the waves. Godzilla would be at home here, and King Kong might wander down from the highlands to look out to sea. There is a monster here, though, and it is very real. It is a killer of the unwary.
Despite the ruggedness of the coastline, residents built a breakwater and boat launch many years ago, and fishing boats plied the waters offshore. A small town was built on the coastal flat, including a  schoolhouse. Accounts describe a pleasant community.

On April 1, 1946, a magnitude 8.6 earthquake struck in the Aleutian Islands of Alaska. The tremor suddenly moved the sea floor, displacing an immeasurable volume of seawater and setting in motion a powerful tsunami. The wave was as high as one hundred feet along the Alaska shoreline, but few people lived there. It was the energy directed into the Pacific Ocean that became the monster that consumed Laupahoehoe. The waves traveled across the ocean at the speed of a jetliner, reaching the Hawaiian Islands just 5 hours later. The waves would have not been noticed in the open ocean because the wave crests were far apart. It wasn't until they reached the shallow sea floor that the full fury of the wave energy would be demonstrated.
The 1946 tsunami hits Hilo Bay
In most places, the first hint that something was amiss was the withdrawal of the water offshore, as stunned townspeople watched. Fish and eels were left flopping on the exposed rocks. Few people knew what it meant and wandered onto the coastal flat, but a several did understand their peril. They started running or driving up the hill, trying to warn others. The first wave to arrive was not catastrophic, being only a few feet high, but the next wave reached a depth of 35 feet (I say "depth" because the wave arrived more as a surge of water rather than a vertical wall). The wave that hit Hilo down the coast killed more than a hundred people, but what happened at Laupahoehoe felt more tragic, if that is possible.
The 1946 tsunami destroys the downtown area of Hilo
The children of the town were at school on the coastal flat. The wave swept away the school house, killing 20 students and four teachers. Only a few children and one teacher survived. Some survivors floated at sea for more than a day before being rescued. How horrible it is to lose most of the kids in a community...I truly cannot imagine.
In the sad aftermath, the town was moved from the coastal flat to the hills above, and the site was made into a beautiful coastal park that almost belies the horrible tragedy that took place here. But the people of the town won't let their lost ones be forgotten. On the small hill above the bay there is a monument to those who were lost and after 70 years there are still flowers and leis being placed in their memory.
There was one positive change that occurred as a result of this horrible tragedy. It was the lack of warning that led to the deaths of so many, and after 1946 the Pacific Tsunami Warning Center was established, providing hours of warning to towns, states, and countries in the path of Pacific Ocean tsunamis. Tens of thousands of lives have no doubt been saved in the decades since. In the Japan earthquake of 2011 the waves that reached Hawai'i could have led to fatalities, but didn't because Hawaiians know what to do when the warnings come.

One can only wish that we had had the foresight to set up a similar system in the Indian Ocean prior to 2004. The magnitude 9.2 Indian Ocean earthquake produced a tsunami that killed 230,000 people.

Saturday, July 16, 2016

Cormorant and Pillow Basalt Above Waikiki Beach (but not the one you think)

I'm still on the road so posts are few, but I occasionally get to a computer. Today's picture is a Cormorant flying in front of a wave-cut cliff exposing pillow basalt at Waikiki Beach. I've been writing a lot about Hawai'i of late, so you are forgiven for thinking that this is one the islands, but it's not. It's at Cape Disappointment on the Columbia River in Washington state. It got the name from an event in 1811 when a shipwreck led to the death of a Hawaiian crewmember whose body washed up on the beach here (I don't know why they didn't just use his name).

The pillow basalt is part of the Crescent Formation, a unit that preserves sea-floor sediments and basalt of the ocean crust that was swept into the subduction zone along the west coast of North America. Pillows are globular masses of basalt that form when the lava flows into water. The lava dates from the middle Eocene epoch, about 40 million years ago.

Cape Disappointment is steeped in history, being the last point of solid bedrock along the Columbia River where it flows into the Pacific Ocean. The name came from the failure of early explorers to recognize this spot as the mouth of the Columbia River (hazardous and constantly shifting sand bars made navigation upstream extraordinarily difficult). It was also the place where the Lewis and Clark Expedition finally reached the Pacific Ocean.
The construction of a huge jetty to make navigation on the Columbia River a bit safer caused sand to back up against the rock barrier, forming an extensive beach where none existed before. The site is now a state park and national historical park. There is a nice campground where we enjoyed some rare sun the other day (Cape Disappointment is said to be the foggiest place in the United States).

There are two lighthouses on the peninsula, due to the aforementioned hazards. Around 200 ships were wrecked in the immediate vicinity over the years.

Wednesday, July 13, 2016

The Hawai'i That Had Never Been: A Mountain That is Younger Than Me, Mauna Ulu

Mauna Ulu, a mountain that originated between 1969 and 1974
So much of geology is incremental. A rock slides from a cliff top, a river carries sand grains downstream, a glacier slowly pushes debris down a mountain canyon. Each of these minor events add up to major changes to a landscape over millions of years: mountains disappear, lakes and seas fill with sediment, canyon gorges are carved. But to a human observer, the changes are invisible. We simply don't live long enough to see the changes that take place in geologic time.

Hawai'i, especially the Big Island, is different. The entire island is less than a million years old, not even 1/4,000th the age of the planet. Because the island sits atop a hot spot, volcanism is a near constant activity, and volcanism leads to major and rapid changes to the landscape. In this current blog series, we've been talking about the "Hawai'i That Was", the environment that existed prior to the arrival of the Europeans, and before the arrival of the Polynesians. But when we look at volcanic activity at Kilauea on the Big Island, we are looking at landscapes that have never existed before. They are new lands.
That's not to say that much is destroyed in the making of new landscapes. The basaltic lava that emanates from the vents along the flank of Kilauea's east rift does a lot of destruction as it flows towards the sea. Take a look at the mound of lava in the picture above. It's a lava tree, formed when lava flowed past a living tree, and congealed around the burning trunk. The level of the lava dropped, but not the solid material around the former tree. The original Hawaiian thought these to be the lithified bodies of humans (although the one above looks much more like a cat).   
My last post on the subject was a discussion of how kipukas preserve a bit of the world that was, prior to the eruption. I said that we visited two of them, but I later remembered that we explored two others as well. It was a trail near Chain of Craters Road that took in two volcanoes, Pu'u Huluhulu, and Mauna Ulu (this is a different Pu'u Huluhulu than the one on Saddle Road).
About 500 years ago, a mildly explosive basalt eruption produced a cinder cone now called Pu'u Huluhulu ("shaggy hill"). Over time, intense weathering of the basalt cinders produced a rich soil that allowed the growth of a rainforest. The forest covered the surrounding landscape too, but that changed not long ago. In 1969 eruptions began along the rift zone that produced lava flows for five years, the longest sustained eruption ever recorded (this record as since been broken by the current Pu'u O'o eruption that started in 1983 and is continuing today).
The lava flows filled around half of the craters along Chain of Craters Road, and covered the road too. The flows piled up against Pu'u Huluhulu as well, but weren't thick enough to overwhelm the hill and the rainforest that covered it. The forest survived as a kipuka. The trail climbs to the summit of Pu'u Huluhulu, and provides what is said to be a spectacular view of Mauna Loa, Kilauea, and Mauna Kea. I'd love to show pictures of the view, but one doesn't get to control the weather when traveling to the islands. We spent much of the hike in a rainstorm with a low cloud deck.
But there was something that we could see: a new mountain. Mauna Ulu is a 400 foot high shield volcano that came into existence while I was starting high school. It's hard to comprehend the pace of geologic change when it is incremental and slow, but it is also sometimes hard to believe how fast things can happen too. There are at least four mountains in the United States that didn't exist when I was born in 1957: Pu'u Pua'i in Kilauea Iki, Pu'u O'o, Mauna Ulu (below), and...the dome in the crater of Mt. St. Helens in Washington state! Rapid geologic change is not confined to the Big Island of Hawai'i...
The hike to the top of Pu'u Huluhulu is mostly level, with a steep climb at the end of a 1.25 mile trail from just off Chain of Craters Road in Hawai'i Volcanoes National Park. Don't miss it if you are ever in the park, and do it on a sunny day. I'd like to see the view!

Monday, July 11, 2016

Unusual Unconformity on California's Lost Coast

Will someone save the unconformity? It's going to gone soon!

Well, okay, there's not much to be done about it, being that the exposure seen here is on the shoreline of one of the most violent storm-ridden coasts in California, and just a half mile or so from the northernmost land exposure of the San Andreas fault. It's at Shelter Cove on California's Lost Coast, one of the longest undeveloped stretches of coastline in the nation. Except for the small town of Shelter Cove, there is wilderness for a distance of about fifty miles, from Fort Bragg to Ferndale.

The underlying rock is part of the Franciscan Complex, a mixture of graywacke sandstone and shale that was deposited in the trench that once existed off the coast of California in Mesozoic and early Cenozoic time. The gray rocks were uplifted and eroded, and after a stretch of time, were covered by the tan-colored breccia or conglomerate. It was part of the wave-cut cliffs, but was isolated by a fluke of erosion. It's in the active wave zone, so it won't be long before it disappears. The wave-cut bench on which it sits may become a future unconformity if it is ever covered by sediment.

Wednesday, July 6, 2016

The Hawai'i That Was: A Tale of Two Kipukas, and Thoughts on the Rarest Plants in the World


Thousands of years ago there was an eruption at Humu'ula Saddle, the broad wide pass between Mauna Loa and Mauna Kea on the Big Island of Hawai'i. The eruption was mildly explosive, so the resulting landform took shape as a cinder cone. At the time, it was a barren peak amidst a forest of native Koa trees. As time went on, soils developed on the cinder cone, and the forest expanded to cover the hill. Much later the situation was reversed because extensive sheets of basalt flowed from Mauna Loa, most recently in 1843 and 1935. They covered the entire saddle area and decimated the Koa forest. Except for the lone cinder cone. A small remnant of the ancient forest survived.
The hill, called Pu'u Huluhulu ("hairy" or "furry" hill) is a stark example of a kipuka, an island of sorts in the middle of lava flows that preserves a portion of the original pre-flow surface and the plants and animals that lived there. The Google image above shows just how isolated the cinder cone is. If you are looking for the "Hawai'i That Was", a kipuka is a good place to start. They are like museums of what once was, but they are far more than that. In preserving the flora and fauna, they provide the genetic material that will eventually repopulate the areas of devastation.
Edge of Pu'u Huluhulu, where plants start to recolonize the lava flows.
There are hundreds of kipukas spread across the Big Island on Mauna Loa and Kilauea. We explored two of them on our recent exploration of the islands: Pu'u Huluhulu at Saddle Road, and Kipuka Puaulu in Hawai'i Volcanoes National Park.  Because it is a hill at the boundary between Hawaii's two largest volcanoes, Pu'u Huluhulu offers dramatic views. It is also a bit schizophrenic: it is composed of cinders from the "plumbing" system of Mauna Kea, but was later intruded by dikes of basalt from Mauna Loa.
Mauna Kea from the top of Pu'u Huluhulu
The forest of Pu'u Huluhulu may have escaped the destruction of lava flows, but it has not escaped alteration by humans. The northwest flank was quarried for cinders in the past, and is still barren on that side (although geologists appreciate the exposure of dikes and cinder layers). Cattle, goats and sheep have grazed the hill at various times, although a fence now keeps them out (as long as hikers close the gates). Several short trails, though steep and rocky in a few spots, provide access to much of the kipuka, and the site is recognized as a hot spot for viewing rare native birds.
Kipuka Puaulu, the "Bird Kipuka", at Hawai'i Volcanoes National Park (forested area in center of picture).

At Kipuka Puaulu (or Kipukapuaulu) in Hawaiian Volcanoes National Park the situation is a bit different. For one, it is about ten times larger than Pu'u Huluhulu, covering about a square mile. It's also more of a depression than a hill. About 600 years ago, a lava flow from Mauna Loa overwhelmed the forest of mature Koa and Ohi'a trees, but left a fragment of the woodland sitting on 8,600 year old lava unscathed. Over the years the kipuka was occasionally mantled with ash from the eruptions of nearby Kilauea, but the forest persisted, in part because the ash produced thick moist soils. Today, the kipuka contains one of the most diverse collections of native flora on the Big Island. A beautiful and serene one-mile trail winds through the unique preserve. A Hawaiian elder calls it a "Residence of Godly Existences".
It wouldn't be quite correct to describe Kipukapuaulu as an untouched pristine environment. Cattle were released on the islands in the late 1700's, and pigs and goats moved in as well. The natural flora of the kipuka had no defenses against the aggressive grazers, and by the early 1900's, the kipuka was a park-like grassland shaded only by the "grandfather trees", the older Koa and Ohi'a trees that the cattle couldn't reach. A park sounds pleasant enough, but the trees couldn't reproduce (the saplings were quickly eaten), and the diverse understory of shrubs and perennials had been replaced by alien grasses (below).
Source: National Park Service (https://www.nps.gov/havo/planyourvisit/upload/Kipukapuaulu_Trail_Guide.pdf)
The potential value of the kipuka as a preserve of rare native species was recognized surprisingly early by botanists, who arranged for the removal of cattle in 1928, and the removal of goats and pigs by 1968 (a fence surrounds the kipuka). Volunteers removed the worst of the invasive weeds and grasses, and seeds of native plants lying dormant in the soils started sprouting. In other cases the native species were planted by hand. After a few decades, the kipuka is returning to a condition that is at least comparable to its natural primeval state.
Hau kuahiwi (Hibiscadelphus giffardianus), once extinct except for a few seeds
Have you ever wondered about the identity of the rarest plant in the world? We recently had a story about a single plant of Franciscan Manzanita in San Francisco, discovered at an intersection that was being repaved. How about a plant with no living shoots or branches? One of the strangest stories I've run across regarding Kipukapuaulu is that of the small Hibiscus tree called Hau Kuahiwi (Hibiscadelphus giffardianus). A botanist named Joseph Rock (with that name he should have been a geologist) discovered the sole remaining specimen of the plant on planet Earth in Kipukapuaulu in 1911 (the cows had not quite finished it off). The one plant died in 1930, but a local resident managed to collect enough seeds to get a few sprouts going, and so the plant survives in captivity, so to speak. Around 200 have been planted in the kipuka that was its ancestral home (as well as the adjacent kipuka, for insurance from possible future lava flows).
The kipuka came under protection pretty much in the nick of time. Some of the "grandfather trees" that shade the preserve have been dying off in recent years (like the trees in the picture above). On species, the Ohi'a tree (Metrosideros polymorpha) is one of the most extraordinary of the native trees in Hawai'i. The Ohi'a thrives in a greater range of environments than pretty much any tree on the planet, being found in places as diverse as new lava flows, desert slopes, and alpine ridges. They can appear as small shrubs or as huge rainforest canopy trees nearly a hundred feet tall. The Ohi'a trees in the kipuka are dying, perhaps of old age, a newly spreading fungal disease, or because of a series of droughts in recent years (maybe all three). With the diversity of plants now in place, one would hope the kipuka would be able to adapt to the loss of the old trees.

 A few steps off the trail is an intriguing opening in the ground. It is a lava tube, part of the plumbing system of basaltic lava flows. Because it has existed for more than 8,000 years, it is one of relatively few that has some species of cave-dwelling organisms (including the first one discovered in Hawaii). Like the rest of the kipuka, the cave was heavily impacted (in this case by graffiti artists, vandalism and trash), but visitors are now encouraged to leave the cave alone.

The preponderance of native plant species attracts the native bird species to the kipuka, and they can commonly be seen flitting about in the forest canopy. They thrive here for two reasons: at 4,000 feet, they are above the mosquito zone, so are protected from transmitted diseases, and mongooses have not crossed the barren lava flows to prey on the birds. They are frustratingly difficult to photograph, and I am actually cheating here by showing a picture of an Apapane from nearby at the park visitor center.

The bird below is often seen in Kipukapuaulu, but it is not actually a native. It is a Kalij Pheasant, a 1962 import from southern Asia. There is some concern about the effects they might be having on the vegetation.

To the average visitor the islands, the kipukas are a little-known aspect of Hawaiian geology and biology, but they are an important link to the past, and an important repository of the island's genetic history. If you ever visit, set aside some time for an exploration.
View from the forest on Pu'u Huluhulu towards extensive Mauna Loa lava flows.
Much of my information in this post is drawn from the Kipukapuaulu Trail Guide, written by Tim Tunison and Andrea Kaawaloa-Okita, and published by the Hawai'i Natural History Association. Additional information was gleaned from the book Hawai'is Native Plants by Dr. Bruce Bohm.