Perovskite is a special kind of mineral, calcium titanium oxide composed of calcium titanate (CaTiO3), discovered first in the Urals and named after Lev Perovski (though it was discovered by Gustav Rose). Continue reading Perovskites and why you should care about them
California’s Amazing Geology
California is one of the most geologically interesting and complex geopolitical units in the world. But so is Minnesota, and Minnesota is boring, geologically, for most people. Why? Because Minnesota is all eroded down and flattened out and covered with glacial till, so most of the interesting geology is buried, while California is actively engaged in its own geology in a spectacular and visually appealing way!
Lots of places have volcanoes. California has volcanoes that blow up, or that have erupted recently enough (geologically speaking) that you can still see the stuff laying all over the place they spewed out. Lots of places have rifting. Hell, one of the most interesting and important rifts in global geological history is right here in Minnesota. But, do people go to Duluth to see that rift, or to see Bob Dylan’s house? The latter, I think. In Califonria, there are three or four different kinds of major tectonic activity, including lots of plate tectonic movement, some spreading, and a big chunk of the amazing Basin and Range extension phenomenon. (That was where what is roughly Nevada and big sections of Utah and California stretched out to several times its original size. In the old days, Reno and Salt Lake Cities wold have been in the same Congressional District!)
California doesn’t’ just have mountains. It has several different kinds of mountains, most of which are currently actively forming right before our very eyes, or so recently formed they still have the tags hanging off them.
California’s Amazing Geology
There are three things you need to know about this book. First, it covers everything pretty completely, considering the vastness of California and the fact that the book is 480 pages long. Second, it is very up to date. There aren’t any up to date books about California Geology. Third, it is written by Don Prothero, which means that complicated and nuanced scientific topics are explained in a way that a reasonably educated non expert can totally understand. Books like this all too commonly fall into jargonistic language either because the author has no clue it is happening, or because they are written for a highly specialized audience (and maybe the author is even a bit insecure). Don Prothero does not do that. He simply gives you the information in a respectfully, clear, understandable, but not watered down manner. A lot of people will tell you that is not possible. They are wrong, and Prothero does it all the time.
The illustrations, many by Don’s son, are excellent and numerous.
By the way, if you want to know more about how one goes about writing books like this, and how Don’s approach works, check out this interview with the man himself.
This is a bit of a specialized book unless you frequently visit or live in California. It is suitable as a textbook in college, but also, in just the right California science elective class. If you you are a modern student of natural history and California is in your catchment, this is a must-have book.
I am a little confused about its availability. The publication date is 2017, I got a pre-publication review copy, but it looks like you can actually buy it on Amazon now
Here is the TOC:
FUNDAMENTALS OF GEOLOGY
The Golden State
Building Blocks: Minerals and Rocks
Dating California: Stratigraphy and Geochronology
The Big Picture: Tectonics and Structural Geology
Earthquakes and Seismology
GEOLOGIC PROVINCES OF CALIFORNIA
Young Volcanoes: The Cascades and Modoc Plateau
The Broken Land: The Basin and Range Province
Gold, Glaciers, and Granitics: The Sierra Nevada Mountains
Mantle Rocks and Exotic Terranes: The Klamath Mountains
Oil and Agriculture: The Great Valley
The San Andreas Fault Zone
Melanges, Granitics, and Ophiolites: The Coast Ranges
Compression, Rotation, Uplift: The Transverse Ranges and Adjacent Basins
Granitics, Gems, and Geothermal Springs: The Peninsular Ranges and Salton Trough
Assembling California: A Four-Dimensional Jigsaw Puzzle
CALIFORNIA’S GEOLOGIC RESOURCES
California Gold
California Oil
California Water
California’s Coasts
California’s Fossil Resources
I want to tell you about a great new book that has one forgivable flaw, which I’ll mention at the end. But first, a word from Bizarro Land. This is about the Grand Canyon.
I would think that the Grand Canyon would be the last thing that creationists would point to as proof of a young earth (several thousands of years old). Just go look at the Grand Canyon. One of the top major layers, the Kaibab Formation, is around 300 to 400 feet thick and made mostly of limestone. That would take a long time to form. But wait, there’s more. Within the Kaibab limestone there are also different sorts of rocks, evaporates, which indicate prolonged dry periods. How can an environment that is forming a thick limestone layer, but occasionally drying out for prolonged periods, be accommodated in a short chronology like required by Young Earth Creationists? This formation also contains fossils of organisms that do not exist today. Certainly, more time than possible in a world that began 4004 BC is required to have produce the Kaibab Formation. And that is just one relatively thin layer exposed by the Grand Canyon, and nearly at the top.
Down lower than that is a thick series of deposits that reflect major changes in Earth’s climate and ecology. These are the rocks that contribute most to giving the Grand Canyon it’s glorious redness and depth. They contain fossil footprints of organisms that don’t exist today. They contain alternating layers with evidence of marine environments and dry land terrestrial environments. Any reasonable understanding of how long it would take for these layers to form requires tens or hundreds of millions of years, even without dating, and one can only estimate that the formation of these sediments was finished long before anything like modern life forms existed.
The rock at the base of the Grand Canyon is separated from the rest by a long discomformity (a period of erosion that wiped out an unknown thickness of rock), so this rock is way, way older than everything else. These rocks are highly deformed and contain no evidence of multicellular life. Laying this rock down and subsequently mushing it all up, then eroding the heck out of took more than 6,000 years! Probably closer to 600 million years!
On top of all this, many of the formations we see exposed in the Grand Canyon are known to be represented a great distance away in other areas, and in some places those rocks form the guts of mountains. How long does it take for continents to squeeze together and move about with such force to form the American Great Basin and Range system of mountains, in Utah, Nevada, and nearby areas? More than 6,000 years! For those mountains to have formed from flatness fast enough to accommodate a young Earth, there would have be be mountains somewhere forming fast enough that you’d need to set the handbrake on your car if you parked there for a day, in case the parking lot went vertical on you.
If I was a Young Earth Creationist I’d try to ignore the Grand Canyon, pretend it isn’t there. But it is there. And everybody knows about it.
One alternative to pretending that the Grand Canyon doesn’t exist is to explain how it got there within a time frame of a few thousand years. But that requires speeding up processes to an unbelievable extent.
So, obviously, the only possible way for Young Earth Creationists to deal with the grand canyon is to fully depart reality and claim that it formed in a very short period of time by processes never before or since observed.
According to the Young Earth version of the Bible, dry land appeared in 4004 BC. Then, the Garden of Eden and all that stuff happened, and then the Noachian Diluvian event happened, the great flood, in 2348 BC. If we assume that the flood created the canyon itself, then all of the rock we see now exposed in the grand canyon was laid down over the course of 1,656 years. But that would be way to reasonable for Young Earth Creationists, who seem claim that the sediments seen in the Grand Canyon were actually laid down by the great flood itself. The canyon was then exposed by a single, later, flooding event when a big lake let out all its water at once.
It turns out that the Young Earth creationists have a lousy argument to explain the sediments exposed by the Grand Canyon, and the formation of the canyon itself. If geologists try to explain the Grand Canyon, however, they end up with an amazing and quite plausible story full of exciting geological and geographic adventure and intrigue. The Grand Canyon turns out to be really cool.
So, the book, edited by Carol Hill, Gregg Davidson, Tim Helble, and Wayne Ranney, is The Grand Canyon, Monument to an Ancient Earth: Can Noah’s Flood Explain the Grand Canyon?
It includes several chapters by eleven experts, all fascinating, all informative, all amazing, talking about various aspects of both the creationist view of the Grand Canyon, and about the real geology of this amazing feature.
Great illustrations abound within this volume.
It turns out that the Young Earth Creationists are wrong, in case you were wondering.
As an aside, I don’t actually think the Young Earth Creationists have to be right, or even believable by non-scientists, to have succeeded in explaining the Grand Canyon. From the point of view of a Christian who wants to take the Bible literally, all you need to know is that there is an explanation. You don’t even have to know what the explanation is. By simply knowing that somewhere out there a team of Creation Scientists have explained away the annoying claims of great antiquity and such, you can go on believing in the literal truth of the Bible. In fact, better to not explore the Creationist explanation, really. You wouldn’t believe it.
It isn’t just that the Young Earth version of the Grand Canyon is wrong from a scientific perspective. It is also the case that the Young Earth “facts” from the Bible are themselves wrong. This book also covers that set of problems. And, of course, the Grand Canyon is way more Grand from a geological perspective than it is from a Biblical perspective. The Young Earth version is dumb and uninteresting. The real version is big, giant, wonderful science.
The book outlines the basic arguments about the Grand Canyon and how they differ. Then, the authors explore some basic geology needed to understand the Grand Canyon, looking at how sediments form, the Earth moves, and what fossils can tell us, how dating works, etc.
Especially interesting to me are the chapters on the canyon’s formation. This is a very interesting aspect of both canyons and mountains that I ran into when developing tourism and educational materials for geological sites in South Africa. Get a bunch of regular people who are not very science savvy. Bring them to a mountain. Then, discuss how old the mountain is.
If the rocks the mountain is made of are 500,000,000 years old, then the mountain is 500,000,000 years old, right? I’ve seen public info documents that use that logic, so it must be true! But clearly the mountain you are looking at was not a mountain five hundred million years ago. It was an inland sea or something. The mountain itself rose up between 20 and five million years ago. So that is how old the mountain is, right? Same with Canyons. It isn’t actually hard to understand that the rocks a particular geological feature are made from would be of one age, but the aspects of the feature that expose those rocks (erosion or uplift) are later, and that the ages of the two things must be entirely different.
It is probably a lot easier to date the rise of a mountain system than it is to date the erosion of a surface or the cutting of a canyon. This is because after mountain building slows down, datable sediments may form in clearly identifiable environments that did not exist before the mountain was formed. But a hole is a bit harder to grok. When the Grand Canyon formed, and how long it took, are actually active and open scientific questions. This fascinating subject, which relates as you might imagine to the creationist story in important ways, are well and fully addressed in this volume.
I asked one of the book’s editors, Tim Helble, what the current open questions and areas of active research are for the Grand Canyon. He told me that one “hot topic continues to be how and when the Grand Canyon was carved. The current Colorado River appears to have integrated multiple drainages and proto-canyons, and how and when they were integrated has attracted a lot of research.” He noted that one of the book’s other editors, Carol Hill, “continues to present evidence that there was a karst (limestone/sinkhole/cave) connection between the eastern and western proto-drainages.”
Also, Tim told me that “the Grand Canyon National Park hydrologist is leading a lot of research on the highly complex groundwater system in the canyon area. This is especially timely with all the recent controversy about uranium mining in the greater Grand Canyon area (which actually goes back many decades).”
An interesting fact is that The Grand Canyon, Monument to an Ancient Earth: Can Noah’s Flood Explain the Grand Canyon?
So, what is the problem with this book?
There really isn’t a problem with this book, but there is a problem with our collective conversation about creationism vs. science. This book addresses a central point in Young Earth Creationism and resoundingly refutes it. But, this is also an excellent book about the Grand Canyon. Personally, I would love to see a book like this that doesn’t waste a page on the creationist story. I want the geology of the Grand Canyon untainted by reference to the yammering of YECs.
I do fully appreciate the role this book will play, and for this reason I recommend it for all science teachers and others who interface with the public in matters of science. No matter what your area of science is, the creationist argument based on the Grand Canyon has become central dogma for that school of non-thought, and you need to know about it. This volume lets you do that in a way that is also rich in real science and very rewarding.
It turns out that while there are some excellent highly technical books on the geology of the Grand Canyon, there is nothing that is super up to date, that covers all of the geology uniformly, and that is beautifully, richly, and correctly illustrated other than The Grand Canyon, Monument to an Ancient Earth: Can Noah’s Flood Explain the Grand Canyon?
I hereby encourage the team that put this book together to also write a post-creationist version that does the excellent science and description, and pretends like the Young Earth Creationists never existed. Who knows, maybe they’ll do it!
As noted, this is a nice looking book, almost coffee table but rich in information, suitable as a gift.
On October 8th, 1865, the “Great San Francisco Earthquake” hit south of the city of San Francisco, magnitude 6.3.
On October 21st, 1868, the ‘Great San Francisco Earthquake” hit near Haywards, east of the city, across the bay, magnitude 6.8.
On April 18th, 1906, the “Great San Francisco Earthquake” hit the Bay Area, magnitude 7.6.
The death tolls were unknown (but small), 30, and about 3,000, respectively.
Eighteen significant earthquakes happened after that (and five or so had happened between the first “great quakes”) before February 9th, 1971, when the Sylmar earthquake (magnitude 6.7, death toll 65) occurred in the San Fernando Valley. So, about 25 major earthquakes happened in California, of varying degrees of significance with respect to property damage and loss of life, since the earliest influx of immigrants associated with the Gold Rush, which is how California got permanently and meaningfully populated by Europeans.
Right after the Sylmar earthquake, a law was passed that required that earthquake hazard be considered as part of the approval process for new development.
One hundred and six years of time during which a significant earthquake occurred about every four years, passed before the first meaningful response by the civilization living on top of these active faults. Civilization does, indeed, have its faults. As it were.
Meanwhile, to the north, in British Columbia, Washington State, Oregon and parts of northern California, earthquakes were not recognized as a problem. They hardly ever happened. Buildings, homes, bridges, gas-lines, and other infrastructure were deployed without consideration of earthquake hazard for decades.
However, the earthquake hazard in that region is probably much greater in some ways than the earthquake hazard around Los Angeles and San Francisco, which are regularly rocked by fault-line activity. Here, the great plates that make up our planet’s surface do something different than they do in the southern California.
In southern California, the plates are mainly grinding past each other. Fragments of the plates separated by fault lines are squishing past each other like an eraser rubbing against paper. It is not a smooth process, but rather one in which pressure builds up and is released at numerous locations, with each of those release events resulting in some sort of earthquake.
To the north, the main interaction between the plates is the subduction of one plate beneath the other. The subducting (going under) plate moves steadily under the continent, with little fanfare other than slowly elevating that part of the continent, tilting of the land upward to the west and downward to the east (relatively speaking). Then, every now and then, there is an adjustment. The top plate drops all at once, causing a major change in elevation that results in coastal areas being suddenly under the sea, and also resulting in a major earthquake, perhaps magnitude 9.
(Remember, each whole number on the scale used to measure earthquakes is one order of magnitude, so a magnitude 9 earthquake is 100 times stronger than a magnitude 7 earthquake).
It appears that the nearly 700 mile long zone of subduction has suffered 19 “subduction zone earthquakes” over the last 10,000 years, with many more affecting a smaller length of this zone. So, long term, a major earthquake affecting an area hundreds of miles long and who knows how wide, and by major earthquake I mean as never seen before by living humans in the region, and hardly ever observed in recent times anywhere on the planet, affects an area larger than many countries.
Same with earthquakes. Sort of. The short term with earthquakes is, unfortunately very very short. We know when an earthquake starts that there will be an earthquake over the next several seconds or minutes. That is a little like predicting that it is going to be raining over the next little while when the first drops fall from the sky. You’ve heard of predicting earthquakes longer term, like over days. Every now and then someone observes something that seems to be associated with the geological processes that produce earthquakes, then there is an earthquake, and bingo, we’ve got a method of prediction. But so far every time this has happened, that method of prediction has been invalidated by reality, when it fails to predict subsequent quakes, or produces false positives.
(An interesting example of this happened just yesterday when a scientist — but not a geologist — happen to observe the presence of huge amounts of various gasses appearing along the coast of California, and thought this might be the indicator of an impending earthquake. This prediction was supported by a several years old research project that suggested that gas outflows might predict earthquakes. I’m pretty sure the gas outflow idea has not developed. And, it turns out that the scientist who observed the California gas was simply looking at a common meteorological phenomenon that involved normal human pollution combined with certain atmospheric conditions. Nothing to see here!)
However, long term, earthquakes can be “predicted” using the term “predicted” in modern vernacular parlance. What I mean by that is that the earthquake hazard for a given region can be estimated over longish periods of time with reasonable certainty. We can say, for example, that there is a 63% probability of there being one or more earthquakes of 6.7 magnitude or greater between the years of 2007 and 2036 in certain clearly defined parts of California around San Francisco. This is based on a combination of empirical observation of earthquake frequency and an understanding of how earthquakes happen. According to one study, there is about a one in three chance of a Cascadia subduction zone earthquake (magnitude 8 or 9 or so) over the next fifty years.
So, when planning development or putting together emergency systems, it is possible to know two things. One, what kinds of earthquakes are going to happen (in terms of location, overall range, and magnitude, etc.) and what is the chance of something like this happening.
From this emerges something rather counter-intuitive. It turns out that the magnitude of the largest likely quake is more important than the likelihood that it will happen during any medium length time period. It does not matter if a magnitude 9 earthquake is 10% or 1% likely to happen over the next 20 years when you are building a major interstate highway bridge or a skyscraper. What matters is that you build the thing to handle a magnitude 9 earthquake (or, I suppose, prepare yourselves for total destruction of the thing, and have a backup plan of some kind). Development in southern California has to deal with magnitude 7-point-something quakes during the lifespan of a major long-lived structure, while development in Washington and Oregon has to deal with magnitude 8 or 9 quakes during the lifespan of a major long-lived structure. The truth is, your highway bridge near San Francisco has a good chance of being shaken by a magnitude 7 quake, while a highway bridge near Seattle may well outlive its usefulness and be replaced or retrofitted before the once in 500 year trans-Cascadia 9+ quake hits. But you still have to build it to handle the quake because you don’t want to be that guy. (Who didn’t, and then everyone died, and it was your fault.)
There is an interesting historical pattern in the recognition of, and in addressing, earthquakes both in the US an around the world. That century plus time period between what should have been a clue that San Francisco was a quake zone and the first meaningful safety conscious zoning regulation happened initially because developers covered up the first few quakes. They pretended they didn’t happen, downplayed, lied, etc. The 1906 quake was too big to really cover up, of course. Covering up switched to lobbying and lobbying kept regulations off the table for many more decades. Then several dozen suburbanites, voters, taxpayers, whatever got wiped out by a quake that really wasn’t all that bad compared to some of the earlier ones, and a law got passed. So this part of the pattern is denial, followed by different kinds of denial, then some more denial.
Denial of what? Science, of course.
The second part of the historical pattern is science progressing. While most early and mid 20th century construction went along blind to earthquake hazard in southern California because people were being willfully stupid, earthquake unsafe construction proceeded in the northern regions because science had not yet figured it out. Then the denial vs. science thing happened, and is still going on. Decisions have been made at various levels of government in the Cascade subduction zone area that will doom people of the future (one year from now, one century from now, we can’t say) to disaster.
Do you find any of this interesting or important? Then you need to read Earthquake Time Bombs
Yeats explains what earthquakes are. Then he discussed the development of earthquake science, and the politics, cultural response, and technological response to earthquakes, starting with the examples I gave above plus the Haiti earthquake. Then he goes around the world to most of the major earthquake zones and examines the same processes — the geology, the geological science, the engineering and political responses, etc. — in each area.
Yeats is an expert on this, and in fact, has been involved in what he refers to, I think correctly, as the “paradigm shift” in understanding earthquake hazard and risk. This is a shift that happens both within the science and the regulatory and social systems that necessarily address the hazards and risks. He also explains the difference between hazards and risks. Yeats is the go to guy when you want to find out about what to do about earthquakes.
How do we know about the 19 subduction zone earthquakes in the Pacific Northeast that happened over thousands of years? What went wrong at Fukushima, and how do the Japanese deal with earthquakes? What about that New Madrid fault in the middle of the US? What about the Rift Valleys of Africa (where I worked)? What are we doing to do next, what is undone, and how do we do it? These are all addressed in the book.
I came away from Yeats book feeling better about earthquakes. I already knew about the Cascadia quakes and a bunch of other stuff, having done research that required an understanding of tectonic processes myself (though this is not my area). What made me feel better is the simple fact that we can adapt to earthquake hazards by first understanding what they are locally, then applying the proper technology and other systems.
The problem is bad, of course, in regions where earthquake hazard is high, and pre-adaptation is not done for any of a number of reasons, including political or economic ones. Yeats contrasts Japan, the most earthquake ready country in the world, with Haiti, one of the least.
Geology is fun. Earthquakes are one place where the rubber hits the road in geology. This book is a great overview and an important analysis of earthquake hazard and risk worldwide. I highly recommend Earthquake Time Bombs
It is like finding a leak in your roof. I remember once up at the cabin, noticing that my waders were full of water and pointing this out to my wife.
“You’re supposed to hang the waders upside down. Keeps dead mice from falling in there.”
Well, I thought, if any mice fell in these waders and weren’t dead, they’d drown for sure. Anyway, I traced the leak to a part of the ceiling in the closet. Eventually I was able to find the place in the attic where the water was probably going down into the closet, but by this time the torrential rain storms that had preceded the discovery of Lake Waders had long passed and I was going on indirect evidence. Over the next few weeks there were more storms, and every now and then I got to look at where the leak was tracing from but always lost track of it.
Finally, my father-in-law and I figured out how to do it. I got up on the roof with a hose, and he got in the attic with a flashlight. I kept pouring water and he kept tracing back drips until we finally found the perfectly round hole, hidden from view at the top by some recently grown lichen. It was an exit wound, like a .22 caliber bullet had exited the roof in an accidental discharge. Or maybe it was an entrance wound. Eventually I decided it must have been a meteor. No particular evidence for that, but it would be the coolest explanation.
Anyway that’s how it has been over the last few decades at Yellowstone.
You know Yellowstone is one of the world’s largest calderas. When it was formed, in a major explosive eruption about 650,000 years ago or so, it must have been a hell of a mess. If something like that happened there again it would totally ruin the day for anybody visiting the park. And, by “visiting the park” I mean living anywhere in North America pretty much.
Early on, Geologists knew there was a magma plume. This is equivalent, in my analogy, to the big rainstorm that provided the water for the leak in the roof. We know it is there because you can see it. As the North American continental plate moves along to the southwest, it passes over the plume, and the plume is the source for lots of volcanic activity including the occasional day-ruining super volcanic caldera eruption, the big Yellowstone eruption being the most recent of those. You can see all the older volcanic activity, and date it, in a somewhat curved line passing upwards in time along the surface of the continental plate. No problem identifying that.
But, how does the surface of Yellowstone, which puts enormous amounts of volcanic CO2 into the atmosphere continuously, has the largest hydro-thermal system on the planet, the occassional lava flow, etc. connect to the lava plume?
A while back scientists used seismic imaging to depict a fairly large and complex magma feature under the surface. This provides the immediate heat and gasses, but it was not large enough or deep enough to be the ultimate source or the connection to the deeper mantle of the earth. They were still in the attic trying to trace back the leak.
Now, scientists Hsin-Hua Huang, Fan-Chi Lin, Brandon Schmandt, Jamie Farrell, Robert B. Smith, Victor C. Tsai, in a paper titled “The Yellowstone magmatic system from the mantle plume to the upper crust,” published in Science, have used even more seismic imaging to locate and map out a deeper, larger batch of magma that is the link between the molten hot deepens of the earth, the part under the continental plates, and the Yellowstone area.
From the Abstract:
The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we unveil a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 km3, ~4.5 times larger than the upper-crustal magma reservoir, and contains a melt fraction of ~2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.
I love the use of the word “unveil” here. “Hey, Duane, I think I unveiled a bullet hole up here on the roof! There’s your problem!”
Anyway, the details are strikingly complex and involved intense geological science. The implications are still a bit unclear. In a write-up by Eric Hand in Science, geophysicist Alan Lavender says this is “a comprehensive view of the magma system from the top of the plume into the crust. [But] this doesn’t exactly match up with our expectations.” Scientists had been expecting the offset between the upper and lower chambers to be in the opposite direction, west rather than east of the plume.
I don’t know. Maybe they were just holding the map upside down. They need to stick a pencil through the hole to verify it as the true source, like Duane did while I was up there on the roof.
Caption for the image at the top of the post:
Fig. 4 Schematic model for the Yellowstone crust-to-upper mantle magmatic system.
The orientation of the model is along the cross-section AA? in Fig. 3. The geometry of the upper and lower crustal magma reservoirs are based on the contour of 5% VP reduction in the tomographic model. The dashed outline of the lower crustal magma reservoir indicates the larger uncertainties in its boundaries relative to that of the upper reservoir (25). The white arrow indicates the North American plate
Calbuco is a volcano in southern Chile. This one erupts fairly frequently averaging about every 20 years, sometimes quite impresively. The largest eruption during historic times in Chile occurred at Calbuco in 1894.
It is erupting now. Evacuations have been ordered. Here is some amazing footage:
How many lakes are there? We don’t actually know. Lakes are often undercounted, or small lakes ignored, in larger scale geophysical surveys. It is hard to count the small lakes, or in some cases, even to define them. A recent study (published in Geophysical Research Letters) examines this question. We want to know how many lakes there are, and how much surface area they take up, in order to understand better the global Carbon cycle (and for other reasons). From the Abstract of this study:
An accurate description of the abundance and size distribution of lakes is critical to quantifying limnetic contributions to the global carbon cycle. However, estimates of global lake abundance are poorly constrained. We used high-resolution satellite imagery to produce a GLObal WAter BOdies database (GLOWABO), comprising all lakes greater than 0.002 km2. GLOWABO contains geographic and morphometric information for ~117 million lakes with a combined surface area of about 5 × 106 km2, which is 3.7% of the Earth’s nonglaciated land area. Large and intermediate-sized lakes dominate the total lake surface area. Overall, lakes are less abundant but cover a greater total surface area relative to previous estimates based on statistical extrapolations. The GLOWABO allows for the global-scale evaluation of fundamental limnological problems, providing a foundation for improved quantification of limnetic contributions to the biogeochemical processes at large scales.
So, there are fewer than thought but they take up more space than thought. Who would have thought?
Interestingly, there are more lakes at higher latitudes. Because of the uneven distribution of land surface in the Northern vs. Southern Hemispheres (more land in the north) this means more lakes in boreal regions, and more specifically, more lakes in previously glaciated regions. This makes sense because glaciation (and deglaciation, melting of the glaciers) produces lakes. The immature terrain produced by a glacier eventually matures with erosion joining streams and rivers to those lakes, making them disappear. If no glaciers return to a previously glaciated region, eventually all the lakes (or most of them) will disappear.
Look at the Congo, Amazon and Nile basins for examples of large inland regions in the tropics. There are very few lakes. Now look at North America north of the maximum extent of the recent (Wisconsin) glacier. Lots and lots of lakes.
I can’t believe we still have to cover this. We know how old the Earth is. The science on this is pretty darn good. It is 4.54 billion years old plus or minus about 1%.
Florida Senator Marco Rubio does not know how old the earth is. Here is what he says about it:
I’m not a scientist, man. I can tell you what recorded history says, I can tell you what the Bible says, but I think that’s a dispute amongst theologians and I think it has nothing to do with the gross domestic product or economic growth of the United States. I think the age of the universe has zero to do with how our economy is going to grow. I’m not a scientist. I don’t think I’m qualified to answer a question like that. At the end of the day, I think there are multiple theories out there on how the universe was created and I think this is a country where people should have the opportunity to teach them all. I think parents should be able to teach their kids what their faith says, what science says. Whether the Earth was created in 7 days, or 7 actual eras, I’m not sure we’ll ever be able to answer that. It’s one of the great mysteries.
Phil Plait has responded with this:
Actually, it’s not a great mystery. It used to be … a century ago. I am a scientist, and I can tell you that nowadays—thanks to science—we know the age to amazing accuracy. The age of the Earth is 4.54 billion years … plus or minus 50 million years. That’s a number known to an accuracy of 99 percent, which is pretty dang good.
Sen. Rubio’s answer, however, is so confused and error-riddled its difficult to know where to start.
And then, Phil goes ahead and addresses that, HERE.
The Maddow Blog also addresses Senator Rubio’s miscarriage of intelligence.
And, the thing is, the actual story about how we know about the age of the earth is not only well established science, but it is intrinsically interesting. Following is from a post I wrote about this a while back, slightly edited:
Short answer: 4,540,000,000 Earth-years, plus or minus 1%.
Long answer: We don’t know exactly because direct dating of the earliest material on the surface of the Earth will only tell use a minimum age; Prior to that, the Earth’s surface was probably molten, and even after that, it may be that the earliest non-molten material has been recycled into the planet’s interior by tectonic processes. Also, the earth is a big round ball of stuff that condensed into this shape from part of a large disk-shaped blob of stuff known as the Solar Nebula. When exactly, given this, did the Earth become the Earth? Since the process took millions of years, we can’t pinpoint the age of the Earth more exactly than a certain range.
Continue reading How old is the Earth?
Look at this map, of a small part of the state of Minnesota:
See the wide channel that runs from left to right with the windy river in it? You are looking at one of the most amazing stories in geological history ever. I’d like to tell you about it.
Continue reading A River Runs By It: Children growing up with science all around them
The law of superimposition says that stuff found on top is younger than stuff found lower down, in a geological or archaeological column. This is generally true, but there are exceptions, mostly trivial and easily understood. If a cave forms in a rock formation, the stuff that later ends up in that cave is younger in depositional age than the rock underneath which it rests (the rock in the roof of the cave, and above).
One of the coolest examples of what seems to be (but really is not) a violation of this Law of Geology is a thrust fault. A thrust fault is essentially a horizontal fault (as opposed to the more common vertical fault) in which rock from one area slides completely over another area. When this happens, the rock at the base of the upper unit (the one that slid over the other rock) is older than the rock on which it rests.
The fault isn’t really horizontal. but it’s horizontal enough for this to happen. And, in fact, the whole thrust-faulting thing is actually fairly complicated, and there are different processes that cause a similar effect. But in the end, you get an older layer sitting on top of a younger layer.
The reason this is not really a violation of superimposition is this: The older rock was actually deposited on top of the younger rock later in time than the formation of the younger rock. In a way, this is not much different than an ancient mountain made of ancient stuff eroding and generating sand that flows downstream and covers some pre-existing sediment. The fact that the grains of sand were formed a long time ago does not make that recently formed sand deposit old. It is young. But it is a young deposit made of old stuff. A thrust fault is the same thing but instead of there being a zillion tiny grains of sand deposited on some earlier sediment, it’s all one big giant piece!
Here’s a couple of photographs of the Keystone Thrust fault. Tell me if it looks familiar to you:
Well, not really.
But, as noted in Eruptions, there is a new swarm of little earthquakes underneath the Yellowstone Caldera. You’ll remember we discussed this here last time that happened. Since that time, of course, we’ve gotten to see what it would actually look like if the world’s scariest caldera (maybe) actually went off:
Continue reading Yellowstone: She’s gonna blow!!!
You have already heard that there has been increased seismic activity at Yellowstone National Park over the last few days. Since December 26th, there have been several earthquakes a day, some jut over 3.0 magnitude, in the vicinity of the north side of Yellowstone’s lake. This is a seismically active region, but the level of earthquake activity being seen now is much greater than seen in perhaps decades (though the data are still not sufficiently analyzed to make positive comparisons yet).
Volcano experts have absolutely no clue as to what this means. A major reason for virtually total uncertainty is that Yellowstone sits on top of a very large caldera of the type that is formed by a so-called “super volcano” and the last super volcano to erupt was a few years (like, 70 or so thousand years) before any seismic or other geological monitoring station were set up anywhere. Indeed, the first really serious data collection at Yellowstone began just over 30 years ago.
Anyway, I’ve got a few resources for you in case you want to explore this further. To begin with, I recommend a look at my earlier post on this matter:
As you have surely heard, the Yellowstone Caldera … the place where Old Faithful and the Geyser Basin reside … has been undergoing increased “activity” including some earthquakes and a rising up of the land. Is this a big problem? Should the evacuate? Should those of us living only a few states away start wearing earplugs?
My sister, Elizabeth, publishes a newspaper in the vicinity of Yellowstone and they’ve got a very comprehensive piece on he caldera. In fact, my sister’s nickname is Caldera Girl. So she really knows her Calderas.
Tracking Changes in Yellowstone’s Restless Volcanic System
…Since the 1970s, scientists have tracked rapid uplift and subsidence of the ground and significant changes in hydrothermal features and earthquake activity. In 2001, the Yellowstone Volcano Observatory was created by the U.S. Geological Survey (USGS), the University of Utah, and Yellowstone National Park to strengthen scientists’ ability to track activity that could result in hazardous seismic, hydrothermal, or volcanic events in the region…
Finally, we’ve got this somewhat hokey but still fun to watch movie of how we are all totally doomed (h/t Caldera Girl).
The good news is, if this sucker blows, global warming is not going to be a problem.
I am personally keeping close watch on the seismic activity in the area and if I see anything ominous I’ll let you know. As soon as I finish packing and driving about 2,000 miles to the south of here.