What the Earth Giveth, the Earth Taketh Away

Seafloor spreading centers and volcanoes create new land every day; seafloor subduction trenches gobble it back up. So who is winning – the land or the sea?

Q: Hi my question is: If you were to add up the length of all the convergent and divergent plate boundaries, would they approximately be equal?

- Julienne Y

A: The mid-oceanic ridge system - a divergent tectonic plate boundary - is the longest mountain chain in the world, extending through all global oceans (including the Sea of Cortez and the Red Sea, but not the Mediterranean Sea). All these divergent boundaries together are estimated to be about 80,000 kilometers in length.

There are estimated to be about 50,000 km of convergent plate margins, mostly around the Pacific Ocean (the so-called “Ring of Fire”). This total includes oceanic (subduction) trench systems, but also land features like the Himalayas and the Alps.

In principle, one would think the different boundaries would average out to be the same, but this doesn't incorporate either fractal behavior nor does it incorporate actual geography (and spherical geometry). From basic fractal theory we know that a 5 kilometer endpoint-to-endpoint segment of any boundary can be equal to or substantially longer than 5 kilometers depending on its rugosity (irregularity). Also, in a simplest topological model, you could have an outer rim of divergent seafloor spreading, and an inner rim of trenches and plate convergence. This may help explain why the latter (trenches) would necessarily be smaller than the former (seafloor spreading centers) in our modern Earth. By the way: this modern 50,000km/80,000 km ratio may have been very different - substantially reversed - when the Pangaea supercontinent was just starting to break up about 500 million years ago, because the divergent margins were inside the proto-continent, and most convergent boundaries would have had to be outside. 

Note that I’ve discussed only the lengths of convergent and divergent tectonic boundaries here. The calculation of volumes of materials “created” or “consumed” at these boundaries is far more difficult. This requires making a rather daunting number of assumptions, in lieu of actual data that are very hard to come by.

Crystals in Rocks

Q: My science teacher and I had a conversation about the crystal formation  on rocks and we got confused. Do crystals form on igneous rocks or  do they form on metamorphic rocks?  - Justin W

A: Crystals form in both kinds of rock. 

A way to think of crystal formation is to envision a crystal mush: As the intruded magma slowly cools (slowly because if it is underground it is well insulated), crystals will begin to form. The slower the cooling, the larger the crystals, in general. Some crystals will settle to the bottom of the crystal-magma mush if they are denser - and if there is no circulation happening in the crystal mush. These precipitated-out crystal accumulations can sometimes be seen in some ultramafic bodies exposed by later weathering - this bottom layer looks like a mat of "crystal toothpicks."  

More commonly, however, the crystal mush is  very active - convecting or circulating with repeated injections of magma from depth, and/or gas coming out of solution - until the percentage of crystals is too great for further circulation. As crystals continue to form, the percentage of the fluid decreases until the entire intrusive body is solidified. Often in late stages of this crystalization process, cracks will form in the intrusive body itself and in the surrounding host rock, and these cracks will fill with the last bits of fluid in the crystal mush, forming veins. Because there is a preferred order of crystal growth, the last-gasp fluid tends to be different from the average composition of the original magma body that entered the crust from the mantle in the first place.

With metamorphic rocks it's a bit different, because the material was solid to begin with, but under deep tectonic or sedimentary burial (or contact with a hot intruding body), the original material (which could be sediments, or could be older intrusive rocks) heats up and partially melts. Then something called recrystalization takes place. 

If you are ever in Tucson, Arizona, look north towards the Catalina mountains. From a distance you can clearly see the original sedimentary layering, but these rocks have been buried at least 15 kilometers deep and then uplifted by tectonic processes. When you get up close, you will see that coarse crystals have formed during this burial-heating process, so it looks more like a granite than a sedimentary rock. It's actually called an "augen gneiss", words derived from the German language where this sort of rock was first described. Even more fascinating is that as you walk farther north in the Catalina mountain complex, the augen gneiss gradually becomes a classic granite. This means that the more northern sedimentary rocks were buried even deeper. Old time miners would say that these rocks were "stewed and cooked."

It's a lot more complicated than this, of course, because there is heat and fluid released when crystals form. There is also contact metamorphism, where a hot intruding body will heat up the edges of the surrounding rocks and change them chemically both via heat and via fluid and chemical transfer across the boundary. 

I hope this answers your questions. 

==Jeff Wynn

Scientism - its Fatal Flaw

Well, *I* believe in SCIENCE!

Heard that before? It's certainly nothing new - it goes back to at least Voltaire.

Scientism is an expression in use for most of the 20th Century, and is often used to refer to science applied in excess - or applied unreasonably. The term scientism can generally apply in either of two ways:

1. To indicate the improper usage of science or of scientific claims,  
2. To refer to a belief that methods of natural science form the only proper elements in any inquiry.

In a broader sense, scientism is also used to describe the invocation of science as a focus of worship, generally by people who would describe themselves as atheists. It's sort of like Methodism, or Daoism, or... you can fill in the blanks here.

Two recent articles, "Lies, Damned Lies, and Medical Science", and "Trouble at the Lab" draw some obvious and frightening conclusions about this approach or life view.

John Ioannidis, a physician and mathematician, published two seminal articles in 2005. They are among the most-cited papers in all of modern science - and they are incredibly embarrasing to scientists. In the first paper, Ioannidis convincingly showed why 80 percent of non-randomized scientific studies turn out to be wrong. Fully 25 percent of supposedly gold-standard (and thus far more expensive) clinical trials gave incorrect results. It is from studies like this that the medical doctors that you and I seek help from base their diagnoses and treatment protocols. Our lives depend on these being correct. These incorrect results include recommendations to use hormone-replacement therapy in post-menopausal women, that mammograms and PSA tests are critical for extending lives, that anti-depressants such as Prozac, Zoloft, and Paxil can help depression, that doing puzzles will ward off Alzheimers Disease, and that drinking lots of water during intense exercise is helpful.

The problem? Not one of these turns out to be true. THOUSANDS of stories in magazine articles have been written based on these published studies. The number of studies that contradict other studies of the same thing are so high that The Week magazine actually has a section called "Health Scare of the Week".

Many physicians, on their own, have discovered that just taking a patient off of every drug can improve their health immediately.

The truly glaring problem: the large majority of these studies cannot be replicated. This means that other groups cannot repeat the same experiments and get the same results. Amgen, an American drug company, tried to replicate 53 landmark studies in basic research on cancer. They were able to reproduce the results on just 11 percent of the studies. In a separate study done by Bayer, the German pharmaceutical company, only 25% of published results could be reproduced. These analyses aren't being published by disgruntled scientists, but by editors in the premier of all science journals: Nature. Dr. Ioannidis says that between a third to a half of  medical research results has been shown to be untrustworthy. He suggests that physicians, when faced with all this potentially lethal error and confusion... simply ignore them all!

Ioannidis' second paper explains why these flawed studies happen and get published in peer-reviewed journals. Without belaboring the details (you can read them yourself), it comes down to many things - but things that compound themselves:

• The "publish or perish" ethos for young scientists to get tenure or grants
• Ignorance of what constitutes statistical significance among most scientists
• Ego
• Fear of reprisals by peers or superiors
• The tendency of scientific journals to publish almost exclusively "new" and "exciting" discoveries
• Bias in research study design, bias in analysis, self-serving interpretation
• Fraud.

This latter issue is interesting, and when identified firmly it is supposed to lead to retractions of published articles. However, a University of Edinburgh study of 21 confidential surveys of scientists worldwide found that only 2 percent of them admitted to falsifying or fabricating data - but 28 percent said they knew of colleagues who engaged in these practices! If that difference hints to you at a broader problem, then give yourself three stars.

The problem with Scientism is that it falls for the oldest trick in the book: it worships at the feet of the Golden Calf. One of several modern versions of the Golden Calf is Science. But like all man-made things, their faith is based on something that is fatally flawed. It is very, very human.

Are we advocating that people not trust science? Absolutely not - just don't bet your life on it, and certainly don't pour your faith and belief into it! Science is still far better and more honest than the The Talking Heads and Corporate Paid Pundits on talk radio or "fair and unbiased" news channels.

~~~~~

Rocks drying?

Some questions to Ask-a-Geologist are so off-the-wall that they rock me back on my heels and make me really think. Here's an example:

Q: is there a type of rock that dries faster than another?

- Shea P.

A: That's an interesting - and delightfully atypical - question. There are at least two issues involved:

1. 1. The rugosity (or ruggedness) of the rock's surface. The smoother it is (like obsidian), the less surface is exposed to water and the less available in the way of nooks and crannies to trap and hold water. A sandstone would likely keep some moisture on it's surface longer than obsidian would.
2. The surface tension/hydration of the rock's minerals. Certain minerals like clays adsorb (some also absorb) water on their surfaces in a pretty strong manner. Bentonite, for instance, will expand on contact with water and it takes forever to dry it out. When I lived in Denver I noticed that the ground sloped up to foundations of our tiny new house. I was emphatically warned by the realtor to not disturbed that grading. If water got under the eaves of my house, he told me, it could be funneled up against the side, and I could get heaving and major cracks in the basement walls as the swelling clay crushed into the concrete.

There's more to the issue than this, of course - there are other variables that include:

• Is the entire rock in contact with air, or is some of it buried? 
• What is the humidity of the air? 
• Is the air circulating?

As an example of how important these are, I was once working in the Saudi Arabian desert. After a day in 40+ C temperatures, I felt sticky with dried sweat, and was determined to bathe. We carried plenty of water with us... but we were also being engulfed in a three-day sandstorm at the time. It was dark, so I took a 5-gallon Jerry can of water, a metal chair, and a towel about 100 meters out into the desert. I tied my clothes to the metal chair to keep them from blowing away, and used a heavy metal sauce-pan to load and pour water over myself. I lathered up and then poured more water over my hair and body to get the soap off. The wind was blowing so hard that I felt stinging sand up to my chest... and realized that I needed no towel after all. The air was so dessicated and moving so strongly that I was dry almost immediately.

~~~~~

Masaya

Anyone who has read 3 Nephi 8, especially if they are aware of some of the details of Mount St Helens' 1980 eruption, have pondered expressions such as "...there were exceedingly sharp lightnings...", "...the city of Moroni did sink into the depths of the sea...", "...the whole face of the land was changed...", "...there was darkness upon the face of the land...", and the "...the inhabitants thereof who had not fallen could feel the vapor of darkness..." that engulfed the Nephites nearly 2,100 years ago.

Central America, of course, is an integral part of the Pacific Ring of Fire, so-called because of the string of volcanoes that all lie just inland from the Pacific Ocean margins. The Ring includes hundreds of volcanoes, among them the huge Cerro Hudson in southern Chile, Masaya in Nicaragua, Shasta in California, Mount Rainier in Washington, Mount Edgecumbe near Sitka, Alaska, and Kenai and Veniaminof, the monster volcanoes of the Aleutians. Farther east, on the other side of the Pacific Ocean, the Ring of Fire includes Bezymiani, Sheveluch, and Mutnovski-Gorely in Kamchatka, and Alaid and others in the Kuriles. The Ring includes Usu, Fuji, and Sakura-Jima, the best-known volcanoes in Japan. We can't leave out Mount Pinatubo in the Philippines, whose 1992 eruption lowered the world wide temperature by two degrees centigrade, and we must include the long arc of volcanoes in Indonesia, including the monster Toba. The phenomenal eruption of the Toba supervolcano around 72,000 years ago may have reduced the proto-human population on Earth to as few as 2,500 individuals.

All these volcanoes (except for Indonesia) lie just inland of the Pacific Ocean margins because they lie just above their sources: the down-going Pacific Ocean seafloor that is being over-ridden by continental margins all around it. Linking the over-riding continental plates with their subducted oceanic plate are huge subduction faults. These are the sources of the largest earthquakes in Earth's recorded history, including the magnitude 9.5 Valdivia earthquake of 1960 in Chile (whose tsunami destroyed downtown Hilo, Hawai'i, about 8 hours later). Other subduction earthquakes include the magnitude 8.7 to 9.2 Cascadia event of 1700, which sank an entire forest in Puget Sound, and whose "Orphan Tsunami" destroyed villages on the Japanese east coast. The magnitude 9.0 Tohoku Earthquake of 2010 triggered the meltdown of the Fukushima-Di-Ichi nuclear plant and devastated the northeastern Japanese coast. The huge magnitude 8.6 Aceh subduction earthquake of 2004 created a tsunami that killed at least 250,000 people along the Indian Ocean margins.

During the Spanish era, regional Central American capitals such as Santiago de Guatemala and Nicaragua, Honduras, were repeatedly destroyed and rebuilt. To say that earthquakes and related volcanic tephra-falls changed the face of the land in Central America would be an understatement.

Since the 1963 eruption that created the island of Surtsey, Iceland, and the 1980 eruption of Mount St Helens, volcanologists have known that lightning storms are closely associated with Plinian eruptions. This is because of the vast electric charge lofted along with the prodigious amounts of volcanic ash that are transported to the stratosphere.

But what caused the "vapor of darkness" described by Nephi? This was almost certainly a smothering blanket of volcanic ash. Mount St Helens, 1980, was a relatively small (VEI 5) eruption. It lofted about 3 cubic kilometers of material, and left nearly a meter-thick blanket of ash in Yakima, Washington, 244 kilometers to the east, within a few hours of its eruption.

To get a handle on a smoking gun for 3Ne:8, we must examine the largest volcanic eruptions in Central America. One way to do this is to accumulate information on tephra falls that reached out great distances - the larger the reach, the greater the eruption. Two events stand out:

• Masaya volcano, Nicaragua, about 2,100 years ago, left tephra as far as 170 km distant.
• Chiletepe volcano, Nicaragua, about 1,900 years ago, left tephra as far as 570 km distant.

Note that these dates are somewhat approximate (they come from Kutterolf et al, 2008, Geochemistry, Geophysics, Geosystems). The Masaya eruption lofted approximately 8 cubic kilometers of ash and tephra, nearly three times more than Mount St Helens. Interestingly, ancient human footprints have been found at Acahualinca - these are 2,100-year-old fossils discovered along the shores of Lake Managua, Nicaragua, frozen in the volcanic ash from Masaya. Both these volcanoes lie eastward of the subduction zone where the Cocos Plate is being over-ridden by the Caribbean Plate at a rate of nearly 7 cm/year. This rate is nearly three times faster than the Cascadia subduction rate, which means that there are proportionally more frequent earthquakes and volcanic eruptions in Nicaragua than in Washington and Oregon. 

I'm just struck by that name: Masaya. 

~~~~~

Adventure

For Bilbo Baggins, an Adventure made life worth living.

For many human beings, adventure is often just being able to claim you were that first at something: the first on a new pitch at Smith Rocks, Oregon, the first to summit K2 in Nepal, the first to free-climb Half Dome in Yosemite...

There are several books at home that I cherish, including

• "Undaunted Courage" - the Lewis and Clark expedition,
• "Sailing Alone Around the World" - Joshua Slocum's first one-man circumnavigation of the Earth,
• "Tigrero" - Alexander Siemel's hunt for man-eating Jaguars in Brazil's Matto Grosso,
• "Endurance" - Earnest Shackleton's Antarctic expedition and Worsely's incredible navigation across 800 miles of the terrible Southern Ocean to South Georgia Island.

There are others, but these are the ones I re-read every couple of years.

I have pondered a definition of "Adventure."  In my opinion it means going off to someplace where few if any have gone.  It does NOT mean a day-trip, or going somewhere that a cell-phone can call for help from. Importantly, it means going someplace where you are on your own.  If something goes bad, it's up to you and your expedition members to work out your own survival. Fail, and there is no record of the fact that you perished - or like the Franklin Expedition to seek the Northwest Passage, archeologists reconstruct your grim demise a century later. 

According to this definition, I and many of our family members have had some adventures:

1. My first, 10-day sojourn in the deep Amazonas forest of southern Venezuela. It was full of amazing wonders, but I nearly died.
2. Jared, Val, and I hiked to - and summited - Mount Roraima ("The Mother of Waters") on the Venezuelan, Guyana, and Brazilian triple-frontier. The trip covered over 50 kilometers on foot, and the last pitch required climbing a crack up a 700-meter (2,000-foot) cliff to an eerie Moonscape at 3,000 meters (9,600 feet) elevation.  Wearing T-shirts, we were promptly engulfed in a sleet-storm. 
3. Louise and Lisa made that same trip the following year - Lisa wore flip-flops most of the way.
4. Louise and Val hiked to the great Auyantepuy - the greatest cliff-sided mountain on Earth - and climbed it - and both nearly drowned in Devil's Canyon on the way.
5. My first trip into the roadless Amazonas Territory of southern Venezuela. I was nearly consumed by insects on this trip, but the real sticker was an encounter with a pair of murderous bandits... who counted us at least three times before they decided there were too many of us (about 20) to cleanly kill. Our Venezuelan counterparts also reminded the bandits that we were American diplomats - and there would certainly be follow-up if we didn't return. 
6. The first Summer Crossing of the Empty Quarter (there are only a handful of true crossings on record). This required driving 1,700 kilometers (over 1,000 miles) over continuous sand dunes in the hottest desert on earth - even Bedouin only venture into the fringes, and only in winter. Neither fixed-wing nor rotary aircraft can venture into this desolate place; we had only intermittent HF radio contact with the outside world. We camped one night in northern Yemen during its 1994 Civil War - because the Saudi border map placed one guard-post fully 72 kilometers (45 miles) from where it actually was. I completed a magnetic survey over an asteroid-impact site called Wabar when the temperature reached 61 degrees C (142 degrees F) - and according to my companions, was unconscious for 20-30 minutes from heat-stroke afterwards. The next day we visited a "weather station" that was so radioactive that my Geiger Counter went off-scale at its highest setting when my back was against the outside wall.
7. The first overnight camping expedition inside Mount St Helens volcano, just as the 2004 - 2006 eruption was ending. I did this to help a crew of desperate geophysicists, but unlike them I chose to walk out, and not take the return helicopter. This meant hiking in incredibly-dissected, unconsolidated boulder fields for nearly 20 kilometers with a 30-kg backpack. I lost a toe-nail and blew out a knee doing it, and no, there was no cell-phone reception. 

I have cherished photos of these trips, and the book Louise and I wrote about Venezuela has 45 photos in it, many from other-worldly Mount Roraima. We made many more wilderness trips, but in most (but not all) cases we had cell-phone or sat-phone access in case of an emergency.

But here's the thing about adventure: there is the up-side (the excitement, the discovery), but there is also a downside: danger, perhaps death. My personal journal while in Venezuela is full of annotations like "I was nearly killed again today..."

If you push the statistical envelope by doing this too often, You. Will. Die.

~~~~~

Earthquakes only during the day?

According to my calculations, the 6th grade means students are around 11-12 years old. If so, then the Rising Generation is full of people a lot smarter than I was at that age. The question below from Ask-a-Geologist is just one of many like it:

Q: Dear Geologist,

Our name is Arianah and Cray and we are sixth grade students at Preston Middle School in fort Collins, Colorado. We are currently learning about how the Earth’s surface changes over time. We are curious about earthquakes. We have a couple questions for you. Is there a common time when earthquakes happen during the day? Also, why did you become a geologist?

Yours sincerely, Arianah and Cray :D

A:

1. Earthquakes are essentially random. We understand why they happen, we understand where they happen, but we do NOT understand WHEN they will happen. There are always aftershocks following a main event, of course, but the main event cannot be predicted. Extensive research has shown that there is no correlation between earthquakes and certain times of the day or external * events - for instance there is no correlation with either the location of the Sun, or of the Moon, or with tides (alignments of celestial bodies, which cause neap tides or spring tides, is called syzygy). Some of the brightest minds on this planet have been searching for more than a half century for some evidence that main event earthquakes can be predicted, but without success. They can be forecast #, but not predicted.

2. I was a solid-state physicist and realized that if I didn’t do something drastic, I would be stuck inside a laboratory all my life with radioactive sources and high-pressure cells. This was brought very much to my attention one day when I had a high-pressure cell blow out and spew Cobalt-60 all over the inside of our lab, and had to call in a special Spill Team. Also, by this time physics as a profession was drifting into a dead end with string theory, and I saw relatively little value to humanity to spending billions of dollars to see if another exotic particle existed. I checked out break-offs of physics, including astrophysics, hydro-geophysics, weather physics, and geophysics, and found the last one to be very exciting. It also got me out into exotic places, like the Venezuelan jungle, the southeastern Alaska panhandle, the Empty Quarter of Saudi Arabia, etc. Geoscience gives me amazing opportunities to visit these places and many more. But even more interesting to me is to be a detective – to be the first to discover something beneath the ground or the seafloor. I was the first to say where the groundwater was beneath the San Pedro Basin in Arizona and Sonora, Mexico, and the first to map where titanium sands lay beneath the seafloor off the coast of South Africa. That’s ever so cool.

* It has been shown that if you inject fluids into certain formations (e.g., deep sediments northeast of Denver, CO), you can trigger swarms of micro-earthquakes. Basically this is the ground shuddering to equilibrate and adjust itself to a slightly new stress regime. However these sorts of events are so small that they are almost never felt.They really are not earthquakes as the general public understands earthquakes.

# A forecast: in other words, there is an X% chance that there will be a magnitude Y event on the Z fault zone in northern California within the next 30 years. This is very, very different from saying that there will be a Magnitude Y event at Z location on X day - that would be a prediction. We can't do that.

~~~~~