Saturday, July 23, 2016

The Hawai'i That Was: Look at the Cute Squirrel! (NOT a squirrel)

First time visitors to Hawai'i will at some moment see a mammal on the islands. The creature is common enough to be taken as some kind of squirrel, but it most certainly is not one. It's not a rat either, but it is representative of the radical changes brought about by the arrival of the humans on the Hawaiian Islands.

Only two mammals were present on the Hawaiian Islands before the arrival of the Polynesians a thousand or more years ago: the Hawaiian Hoary Bat, and the Hawaiian Monk Sea. It's not difficult to understand why: it's hard for any creature that can't fly or swim to get to the islands. Animals have been known to float on mats of vegetation across seas, but it has not happened in Hawai'i. The Polynesians brought animals with them when they colonized the islands, including pigs and rats. Goats, sheep and cows arrived with the Europeans in the early 1800s. They had a devastating effect on the native ecosystems of the islands, but this "cute" squirrel-like animal stands out. It's the Small Asian Mongoose (Herpestes javanicus).
Sugar cane production became a mainstay, for better or worse, of the Hawaiian economy in the 1800s, but the rats and other pests, mainly insects, wreaked havoc with the cane fields. Common Mynas were introduced in 1865 to deal with the insects, but in 1883 someone had the idea of introducing the Mongoose to chase down the rats. It didn't work. The rats were active at night while the mongooses hunted in the daytime. They did little to control the rat population, but they turned out to be devastatingly efficient predators of the native bird species of the islands, especially the endangered Nene (Hawaiian Goose), the Hawaiian Crow, and Petrels. They prey on the eggs of the endangered Green Sea Turtle as well.

The mongooses run rampant on the Big Island, Mau'i, and Oahu, but were never released on Kaua'i or Lana'i. Efforts are made to trap them, but they are simply too widespread and populous for there to be much hope of containing them. These actions are concentrated on Kaua'i where one was captured in 2012. In their natural habitat in Asia, their predators include snakes, hawks, jackals and storks. Snakes and jackals would be an even worse disaster on the islands (the Brown Tree Snake eliminated nearly all the native birds of Guam). There is a native Hawk on the islands, but there are not nearly enough of them to control the mongooses, and mongooses actually prey on the young hawks at times.
The rats may have been introduced as a food source, or they were stowaways, but they had a horrible effect on the plants and animals of Hawai'i. The mongoose was introduced to control the rats, but they didn't. There are feral cats and dogs on the islands now. It almost sounds like a childhood song...

I knew an old lady who swallowed a fly,
I don't know why she followed a fly, 
Perhaps she'll die...

I knew an old lady who swallowed a spider,
That wiggled and jiggled and tickled inside her,
She swallowed the spider to catch the fly,
I don't know why she swallowed the fly,
Perhaps she'll die...

In case you don't know the song, we eventually end with a horse, and she's dead of course...


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.