Tuesday, November 29, 2016

Fog Returning to the Great Valley...Maybe

The fog here in the Great Valley is legendary. The so-called Tule Fogs can last for weeks, hiding the land in an impenetrable mist. People who would panic at the thought of driving with their eyes closed continue to speed through these fog banks where the visibility is measured in feet rather than tens of feet. One such accident in 2007 involved 90 cars and 18 big-rig trucks, with two people killed.

The Tule fog is a radiation fog, caused when heat from the ground radiates into the atmosphere at night, cooling the ground and causing condensation to take place. The fog persists as long as the temperature doesn't rise, and in the Great Valley, ringed is it is by high mountains, the conditions may persist for weeks at a time. Stable motionless air develops an inversion layer that can be difficult to break up unless a large storm blows in.

I was not prepared for the fogs when I made the valley my home nearly 30 years ago. I hated the gloomy days that seemed to never let up for weeks at a time. I had frightening near-misses on the highways. I even got lost a few times in the pre-GPS days, getting disoriented on backroads that were poor in signage. I was known to drop important projects and drive into the Sierra Nevada foothills for the sole purpose of getting into the sunshine. I hated descending back into the soupy mess.

The drought in California has caused a drop in the number of foggy days, since wet ground is a major requirement for forming the hated mist. Global warming plays a role, as warmer conditions are less likely to result in foggy conditions. Temperatures in some parts of the Great Valley are up by 3 to 4 degrees Fahrenheit. According to one report, the number of foggy days in Fresno declined from an average of 37 in 1980 to 22 in 2014. This has been a two-edged sword: besides the reality of the drought itself, the lack of cold wet conditions have caused a drop in agricultural production, as a number of fruit trees like cherries and peaches require the cold dark days to help the trees go dormant in winter.
I'm seeing fog on the early mornings when I make my way to work through the pasturelands outside my village. They've added an aura of mystery to the landscape, and haven't yet interfered with my driving, so I'm seeing beauty right now. We just finished a series of storms, and conditions will be stable and calm for the next 10 days or so. We'll see how I feel if and when the fog sets in.

Friday, November 25, 2016

Monitoring the California Drought, Via the Road

Add caption
The drought this month. Source: http://droughtmonitor.unl.edu/Home/StateDroughtMonitor.aspx?CA
Drought conditions, February 2015


Tuesday, November 22, 2016











Saturday, November 19, 2016



Until next year!

Friday, November 18, 2016

The Hawai'i That Was: The Lost Wetlands of the Mana Plain on Kaua'i

The Hawai'i that was...

This blog series has been looking at the natural history and geology of the Hawaiian Islands against the backdrop of the changes brought about by colonization around a thousand years ago, and again around 200 years ago. The first wave of humans were the Polynesians, the second, the Europeans and Americans. The changes brought to the islands have been profound, even catastrophic. Dozens of birds species and other animals are extinct, and the landscape itself is much different than it was a thousand years ago.

Out on the west side of Kaua'i is one of the more interesting places that hardly anyone ever sees. This is in part because a large part of the coastal plain is the property of the U.S. military, a missile testing range. Much of the rest is owned by agricultural interests, and the property is closely watched because genetic testing and crop breeding is taking place, rather than simple crop production. A bumpy dirt road winds along between the properties, leading to a state park at Polihale Beach and Barking Dunes.
This is the Mana Plain, which historically was the second largest wetland complex in all the islands, covering an area of about 1,700 acres (nearly three square miles). As a rule flatlands are a rarity on the islands, so Mana really stands out. It developed when the sea was at a slightly higher level, and waves washed across the surface, eating away the base of the cliffs to the east (see the map below and the picture above). Such landscape features could be called a wave-cut bench or a coastal plain. Most of the Mana Plain lies at an elevation of less than 10 feet (3 meters).

The longest continuous sand beach in the Hawaiian Islands extends for 12-13 miles along the Mana Plains. Onshore winds picked up fragments of coral and blew them inland, forming scattered dunes across the plain. Groundwater would well up here and there, producing a number of ponds and wetlands. The region was once one of the most important bird habitats on the islands. That was then. That was the Hawai'i that was.
The Mana Plain in 1907. Source: http://islandbreath.blogspot.com/2013/08/the-golden-plain.html
The Polynesian colonizers, the original Hawaiians, made use of the Mana Plain. It was a rich environment for fishing and bird hunting. The Hawaiians also built fish ponds and levees for the production of taro and sweet potatoes. Despite the various engineering projects, the Mana Plain retained much of its original character. The region was sacred to the native Hawaiians, as the cliff at the north end of the plain, Haelele, was a leina-a-ka-uhane (path-for-leaping-by-the-spirit). This was the place where departing spirits of the ancestors leapt into the sea to enter the realm of the dead beyond the setting sun.

In the 1800s, the swamps and ponds began to be drained and sugar cane and other crops were planted in the newly available fields. By the 1920s, nearly all the wetlands had been drained. The military established their missile tracking facility. Little was left of the original environment, and the rare and endangered shorebirds of Hawai'i had lost a major percentage of their original habitat.
Then, a small thing happened. Sand was a valuable commodity, and several gravel pits were dug on a 35 acre plot in the midst of the plain. Groundwater flowed into the quarry, and some of the endangered shorebirds took up residence. Recognizing an opportunity, officials of the state of Hawai'i established a modest refuge, the Kawaiele Waterbird Sanctuary. Seven more acres were later added, and work is commencing on an even larger plot of 105 acres. It's nowhere near enough, but it's a start.
I didn't know any of these things as we explored the west end of the island on the very last day of our visit. We saw the sign along the highway and pulled off to have a look. The sun was already low in the sky, but we caught sight of several native birds. There was a Black-crowned Night Heron (Nycticorax nycticorax hoactli). The bird, known on the islands as 'Auku'u, is virtually identical to its cousins on the American mainland.
There were also several dozen Ae'o, Thousands of years ago, a few Black-necked Stilts from the American mainland were blown off course, and somehow survived a 2,000 mile journey to the Hawaiian Islands. In the isolation they found there, they evolved ever so slightly from their mainland cousins, and are now considered a subspecies (Himantopus mexicanus knudseni). With their favored habitat being in short supply on the islands, their numbers are not large, only about 2,000 individuals. They are considered highly endangered.

It's said that if the spirits of the deceased did not have family members in the sea to receive them, they would wander this landscape, attaching themselves to rocks and other features. I don't like the thought of being lost in eternity. I'd like to know that they found happiness somewhere in this place, perhaps among the birds of the refuge...

Wednesday, November 16, 2016

The Hawai'i That Was: What the Worst Disaster You Can Think of? The Terror of Na Pali...

Wait, what? Terror? Na Pali? That place isn't terrifying, unless you have a fear of heights. It's one of the most beautiful places on one of the most beautiful islands in the world. What could be scary about it?
Well...there's history, and geology. What's the worst disaster you can imagine happening in the place where you live? Are big earthquakes possible? Volcanic eruptions? What about hurricanes or tornadoes? On our adventure today, we visit the site of one of the greatest natural disasters possible.

Kaua'i is a modest island by Hawai'i standards, covering only 553 square miles, fourth in size after Oahu, Maui, and the Big Island. Unlike the other islands, it was principally a single basaltic shield instead of four or five like the Big Island and Maui (it's a little more complicated than that, but I will deal with that story later in another post). It's also the oldest of the major islands, at about 5-6 million years. The coastal areas of the island are of mostly gentle topography, but on the northwestern side of the island, that gentleness ends. Dramatic cliffs 3,000 feet high drop precipitously into the Pacific Ocean. Welcome to the Na Pali. Why are these incredible cliffs here? And what does that have to do with disaster?
Try to imagine a much younger Kaua'i maybe 4-5 million years ago. The shield volcano rises to an elevation of perhaps 8,000 feet above sea level, and the slopes of the mountain are covered with dense rainforest. Myriad species of birds fly among the trees, along with thousands of species of insects and gastropods. All of them are unknown to humankind, because the kind of humans that would pay attention to such things would not be present in the world for a long time. All that was here was about to be lost.

The islands may feel permanent and unchanging in some ways. The lava flows that emerged from the shield were solid and hard and one might feel that they would not be easily eroded or altered by time. That's a delusion, of course. The volcanic rocks were originally deposited on the sediments of the seafloor, and many of the original lava flows were composed of relatively unconsolidated rock, small cinders and ash layers that are not nearly so solid as the lava flows above. The sheer weight of the overlying lava flows exerted such tremendous stress on the unconsolidated rocks that they destabilized and commenced slowly giving way in a lateral sense. The flanks of the island were weakening.
It's not at all entirely clear how the end came about. There may have been earth movements for centuries, maybe even violent earthquakes that produced scarps high on the flanks of the volcano. Such cliffs can be seen today on the southeastern margin of the Big Island near the Kilauea caldera. The quakes may even have produced small tsunamis that swept across the lower shores of the island. But these events would not have affected the animal of the rainforest all that much.

Maybe there weren't any warning signs. I find that to be less convincing, but maybe the end came suddenly, with no precursors. It didn't matter then, but we'd sure like to know today what transpired, because it would be nice to have some warning when an unimaginable tragedy is about to strike.
In any case, the final stroke must have come quickly. Who knows what kinds of sounds were heard as a significant percentage (a fifth? a quarter?) of the entire island suddenly broke away and sank into the sea? The collapse was so rapid that the debris flowed for sixty miles (100 km) along the sea floor. The rapidly sinking land broke up into large chunks and disappeared beneath the turbulent waves. Some of the fragments were miles across. The homes and habitats for hundreds of species disappeared in an instant, never to be seen again.
The loss of a significant part of the island beneath the waves was only part of the story. Displacements of ocean water on this scale produce tsunamis of unimaginable size. We aren't talking about the 30'-40' high waves of events like the tragedies of Indonesia in 2004 or Japan in 2011. We are trying to imagine a wave that exceeds a height of 1,000 feet. Or considerably more. There are chunks of coral on the island of Lanai that presently sit 1,300 feet above sea level. And Lanai is and always has been slowly sinking. Those blocks of coral were tossed there by mega-tsunamis that were produced by similar catastrophes on other nearby islands.

So first, a huge portion of the island sinks into the ocean, and then the water rises in response and sweeps across vast swaths of Kaua'i and the other Hawaiian islands. The level of destruction is incomprehensible. How many species went extinct that day? No one can ever say. Where a coastal plain once existed, there were only cliffs. Immense cliffs. In time, vegetation returned, and erosional processes sculpted the escarpment into the beautiful fluted cliffs we see today along the Na Pali coastline.

One immediately has to wonder whether it could happen again. The answer is, of course, sure. But these events thankfully don't happen often, maybe once every 300,000-400,000 years. And for now, knowing they have happened in the past, we'll perhaps recognize some of the warning signs that such a slide is again imminent. For the time being, we can instead appreciate the beauty that emerges from catastrophe.
The cliffs of the Na Pali are a bit difficult to see. You can drive to Kalalau or Pu'u o Kila lookouts above Koke'e Park and look down from the cliff tops to the sea (see the top picture in this post). These are two of the most astounding views I've ever seen in my life. You can walk the 11-mile long Kalalau Trail that winds along the base of the cliffs (an adventure I've longed to try). Or you float in the sea offshore for an astounding view. Some people take kayaks (another dream), and others take cruises. I had that opportunity in 2006, and that's when I took most of these pictures.
This post is part of a long-running blog series on the geology and history of the Hawaiian Islands, based in part on our summer field studies journey of last June.

Sunday, November 13, 2016

Supermoon! Well, Really an Excuse to Be Out at Night on the Tuolumne River

The SUPERMOON is really a lot of unnecessary hype that doesn't really mean much. You'd think the gigantic moon would be grazing the outer edge of our atmosphere and causing supervolcano eruptions and earthquakes. I'm sure people will be drawing erroneous conclusions about the tragic earthquake earlier today in New Zealand, but there is very little actual correlation between the position of the earth, moon and sun (see this USGS note on the subject). Earthquakes happen when they happen.

Supermoons are only a bit larger than the average size of the disk of the moon in the sky, around 10-11%, but a fair bit brighter, about 30%. You can compare the full moon from tonight (above) with the size of the moon just prior to the lunar eclipse of April 2015 (below). Still, "they" are saying this is the closest the moon has been to the Earth since 1948. I guess that is something.
Really though, the value of the hype is getting people to go outside and see what is happening in the sky. We made it an excuse to go out to Robert's Ferry Bridge on the Tuolumne River in the Sierra Nevada Mother Lode. It was exceedingly pleasant to stand on the bridge, listening to the water gurgling under the bridge supports. Things were swimming in the river (we didn't know what; it was dark), owls were hooting in the trees, and a pack of coyotes were howling in the distance. One of my time exposures turned out pretty well (below). It was a peaceful moment on a beautiful river.

Two Kinds of Falls Today in Yosemite Valley

There are two kinds of falls right now in Yosemite Valley. One comes from the time of year, and the other is a little bit unusual, the result of some powerful storms a few weeks ago.
Fall in California is not like fall in other places. It may start in the high country in late September, but it can take until mid-November at the lower elevations, for instance in the Great Valley or Bay Area (our most intense colors in town have yet to materialize). And even though fall started weeks ago in places like Yosemite Valley, there are still enough leaves hanging on to provide a colorful treat to visitors this weekend.
The other wondrous fall is that of the waterfalls in the valley. They are often still dry at this point in the year, as few storms have usually occurred this early. But the intense storms of two weeks ago are still draining over the brink of the valley walls. I wrote about the waterfalls two weeks ago when we visited in the midst of the storms, but I wasn't expecting to see them still going after all this time. It was a beautiful sight.
So enjoy some beautiful colors! In the picture above, Upper Yosemite Falls peeks out between the trees near Yosemite Lodge.
Sentinel Dome is a striking tower of granitic rock that is sometimes missed because it is on the valley wall opposite of Yosemite Falls.
Coming from the northwest entrance on Highway 120, the first view of the valley includes Half Dome and the top of El Capitan.
Yosemite Falls remains one of the most awesome sights on the planet. It drops a half mile over a sheer cliff and through a maze of granite clefts. To see the falls flowing while fall colors remain (barely) on the trees is a special treat.
Fall colors come in small spaces as well. We walked through the fen at Happy Isles and saw all kinds of color in the low shrubs and ferns. Water always flows here from springs in the rock debris at the base of the nearby cliff.
I had one other special treat today by taking a few moments to walk up the Inspiration Point Trail above Tunnel View. I got 200-300 feet above the parking area, and away from the noise of traffic and tourists. From my quiet vantage point, I had a glorious view of the entire valley. The only sad note is that what looks like fall color in the valley is not. The reddish patches in the forest are dead conifer trees, victims of California's ongoing five year drought. Without sufficient water, the trees don't have enough sap to fight off the borer beetles. It's just one more sign of the profound effect global warming is having on our world.