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
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? is published by Kregel Publications, in their Biblical Studies series.
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.
The Great San Francisco Earthquake(s)
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.
Will Seattle and Portland Suffer Cataclysmic Earthquakes Any Time Soon?
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.
Can earthquakes be predicted?
It is said that earthquakes can’t be predicted, but from the point of view of regular humans (as opposed, say, to geologists or statisticians) they can be. Many people think weather can be predicted, right? Well, not really. We can make long term predictions of months or even years about overall changes in the climate, and we can predict what the weather will be like in several hours from now. But anything in between is largely guess work except in a few rare cases (the track of hurricanes can sometimes be predicted pretty well several days out, even before they exist, at least roughly).
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.
How do we adapt to earthquakes?
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.
A great new book on earthquakes: “Earthquake Time Bomb” by Robert Yeats
Do you find any of this interesting or important? Then you need to read Earthquake Time Bombs by Robert Yeats.
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 by Robert Yeats.
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
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.
If water had its way, this is what California would look like:
Think about it for a second. Every single moment, currents of air move, slowly or rapidly, across every land surface on the planet. Anything loose gets blown slowly or rapidly, to lower places. Every now and then, in some places rarely and in other places commonly, liquid water falls from the sky on almost every land surface on the planet. Now and then, in certain limited areas, frozen water builds up to great heights, thousands of feet hight, and moves along, scraping deep hollows and grooves the size of big lakes out of these land surfaces. Now and then the earth shakes and stuff falls down. Most of the earth’s surface is ocean, only a small percentage is land. With all this blowing and washing and scraping away, you would think that all the stuff on the land would eventually end up in the ocean and all of the land would look like this:
There are several reasons this does not happen. One is that mountain building happens because continental shelves push against each other. Another is that volcanoes occasionally spew ash, lava, and stuff out onto the land surface. Also, there is another, less often known about by the average person but incredibly important reason that the land does not look like this …
Underneath the land there is melty-squishy-hot stuff that tends to push upwards a little bit almost everywhere, and a lot in some places, though it is usually pushed back upon by the weight of the land itself. If you remove a bunch of stuff from the surface of the continent, this pushing gets a bit of traction. So, if you have a big piece of continent with erosion happening all the time on the top, this pushing will happen from below, and the continent will not disappear below the surface of the sea. The Congo basin is probably an example of this. It rains a lot, there is constant erosion. So, the land surface across most of the Congo has been eroding for something like a couple or few hundred million years, at least, like it is now. As the surface is eroded away, the underneath slowly rises. So now, much of the Congo basin has deeply eroded rivers, and all the hills between the rivers are made of stuff that is like granite, the cooled down, hardened melty-squish-hot stuff. In fact, a lot of Africa is like that.
In California, the last calendar year was the driest one on record. California has been so dry over the last few years that it is nearly dried out. The reservoirs are puddles, the groundwater is a mystery, and the state is in a state of crisis. But today, the first Pineapple Express of the rainy season arrived, and dumped huge amounts of rain in parts of the state.
California is uplifted. Unlike Louisiana, Mississippi, and nearby areas, which are all very close to sea level, California stands up high over the ocean. When you head for the ocean from inland, depending on where you start, you may have to cross significant mountain ranges or linear arrangements of tall hills, and just before getting to the sea you will have your brakes on a lot of the time because you’ll be going down hill. The shoreline of California is roughly synonymous with the continental shelf, in contrast to other coastlines in the US where the shelf edge may be hundreds of miles out to sea.
The dry conditions over the last few years have resulted in a lot of fires on the hills in this hilly, uplifted country. The geological stuff underneath the surface in much of California is not like the deep hardened magma of the Congo, or for that matter, New Hampshire, Maine and the Maritimes. It is soft, to varying degrees. The top, exposed areas on those hills is made of rocks and dirt. When torrential rains flow over the surface, this material is held in place by a combination of plant roots and luck. The force of the rains is attenuated by the upper parts of the vegetation. But with the vegetation either burned off or dead(ish) from drought, or both, the water washes away the softer smaller particles, leaving the larger stones and rocks exposed, and rivulets start to form and erosional gullies deepen and widen. Meanwhile the ground soaks up water and becomes both loose and heavy at the same time. All these factors together constitute a step in the process of making California look, eventually, like this:
And if your house, or the road to your house, or anything, is in the way, it will get washed down stream or buried under other stuff washing down stream. For this reason, evacuations are underway in parts of the Sunshine State.
There’s good news, though. Even though the forces of nature seem intent on making California eventually look like this:
There are other forces of nature that are intent on making California look like this:
That’s the good news. The bad news is that those other forces are, well, earthquakes.
Look at the rock on the right, and the lack of rock on the left. (Our left.) It is being reported that this jelly-donut size rock appeared out of nowhere on the Martian surface between photographs.
There are several possible explanations for this.
1) It grew there.
2) It was ejected from a steam vent or something and flew there.
3) This is what a Martian looks like. It will eventually move on.
4) The robot that took the first picture tossed the rock up while driving by.
5) It is a jelly donut.
6) The rock was placed there to cover up a footprint.
What do you think?
I love it when stuff like this happens.
Usually when I mention The Hobbit I’m talking about the hominid, or something related to the hominid, or a book about the hominid. But here I want to point you to something related to the book by Tolkien and, of more immediate importance, about the science of the Hobbit and things related. You’ve certainly already read this important book about the Science of Middle Earth. But you may not yet have seen this blog post by my friend Matt Kuchta on the geology of the Lonely Mountain.
Like many of you, I saw The Hobbit: The Desolation of Smaug last weekend. Like many of you, I’ve read “The Hobbit” several times (and had it read to me many times before that). But how many of you have wondered what kind of mountain the Lonely Mountain really was?
So, click here to find out.
Everyone knows that Darwin was a biologist, and in many ways he was the first prominent modern biologist. Though Darwin scholars know this, many people do not realize that he was also a geologist. Really, he was mainly a geologist on the day he stepped foot on The Beagle for his famous five year tour. This is especially true if we count his work on coral reefs as a geological study, even though coral reefs are a biological phenomenon. After all, the standing model for coral reef formation at the time came from the field of Geology.
To exemplify this, I’ve put together a list of several of Darwin’s print publications with their publication dates:
I remember finding out about the Tethys Sea and being really excited. I was just beginning my studies of Old World prehistory, Africa, and Human Evolution. What I learned about was the remnant sea separating Africa and Eurasia called Tethys, though it is much more than that (see below). Imagine a Eurasia with no Alps, no Caucasus, and no Arabian Peninsula. Much of southern Europe and huge swaths of North Africa are underwater, and Africa is so far away from Eurasia that all the classic seas of the region don’t exist simply because they are part of the ocean. If you were in the western Mediterranean, you would be able to travel across what is now the Black Sea to the Caspian Sea or the Persian Gulf and into the Indian Ocean, where you would not find India any where near it is today. That was all the Tethys. It allowed the world’s oceans to communicate not too far from the equator across the old world, instead of having the Indian and Atlantic oceans separated by Africa. Virtually everything about the modern climate system depends on tropical or subtropical closure of the major oceans. The fact that the Indian Ocean is on the equator and cut off from the North Atlantic determines and explains almost everything about Northern Hemisphere weather. The rest is explained by the Isthmus of Panama. Had Africa (and India) not moved north to close this sea and create the modern puddles known as the Caspian, Black and Aral seas, and the Persian Gulf, etc. there might well be no Atlantic Hurricanes, England would be rather cold, Canada might look much more like Greenland all year round, and if we add India moving north into Asia into the mix, and the formation of the great mountain ranges of Europe and Central Asia, we also get the present configuration of grasslands in Africa, and in fact, the evolution of grass itself. Prior to the closure of the Tethys, there was an oceanic habitat in Northern Africa and what is now Pakistan and Afghanistan in which evolved hippos, manatees, whales, and elephants. Probably. The sea was enormously influential and it’s demise equally so.
You know the story of Renaissance era scholars noticing sea shells made of lime stone high in the alps. Go look at the alps. Well, the geology there is pretty complicate, but the short version is that many of the fossil bearing (and other) sediments that the alps are made of were party of the western extent of the Tethys, during times when the Atlantic Ocean didn’t happen to exist, so if you were in a boat in that part of the Tethys you would not only be near Geneva (which didn’t exist yet) but also near Libya, Spain and Labrador. When the Tethys was finally pinched out the Alps, Caucuses, and other mountain ranges in the region were pushed up and those sediments exposed.
I’ve had close friends and colleagues who worked on a number of paleontological finds, and in some cases, I worked on them as well, that owe their existence to these dynamic changes. The hominoids of Pashalar were buried in sediments caused by landslides caused by uplift as Turkey became a place; The Siwalics, where all those amazing Asian pre-orang fossils were found, were once lowlands just risen from the sea, and later became the mountains of Pakistan. We will not speak of the Sahavi expedition, other than to say what is now among the driest deserts was once a sea in which it is possible, but highly unlikely, that early human ancestors rode on the back of dolphins swimming among hungry sharks. Well, the dolphins were swimming around among the sharks, anyway.
My own musings about this one thing … the sea that separated Africa from Eurasia, then went away as lands rose up and mountains formed, only addressed the latest period of the Tethys Ocean’s life. Like we have, mainly, the Atlantic and the Pacific today, in the very ver old days, even as life was just beginning to get complicated (and I don’t mean as in too many errands to run before Christmas, so much as I mean having more than one cell and organelles and stuff) it was the Tethys Ocean and the Panthalassic Ocean, the former to the east of, the latter to the west of, Pangea and the various daughter continents of Pangea as they formed over hundreds of millions of years.
It was in the Tethys that the Black Shales formed, during several (but many a few during a certain time period) in which a very large percentage of our oil was to be found, in many cases raised to dry land were it was easy (too easy, as it turns out) to get at. So, the Tethys sea gave us whales, and we used those for a while, but it also gave us Arabian Oil (and lots and lots of other oil around the world) which we are just now running out of.
So, given all this you can imagine how excited I was to see a book written just about the Tethys sea by an expert on it, who helped a great deal in developing our knowledge of it. Vanished Ocean: How Tethys Reshaped the World by Dorrik Stow is the story of the Tethys, told from the very beginning which is about a third of the way back to the very beginning of time itself, it’s fascinating disappearance. Stow is professor of Geoscience at Heriot Watt University, Edinburgh, and has a long history of research in oil geology and interpretation of deep sea cores. He was on some of the key deep sea coring projects that led not only to our understanding of the Tethys, but also, climate change.
To me, one of the most unsatisfying things one can do is to go to a place with interesting geology, stop in at the visitors center with the cute little museum, and see the same exact thing every time: “This region was once covered by a vast inland sea, bla bla bla” because those interpretive exhibits NEVER tell the most interesting aspects of the story. Like, the nearest shore off in that direction, even though you are currently in Michigan, was Norway and you could see if from here. Or, the rock formed by the reblown sand left behind when the sea receded is the same rock that outcrops at the other national park you visited five years ago and a thousand miles away. Or the wavy lines in this rock are from actual waves at the top of the water that were influenced by a wind that blew down from a mountain ridge that is now a low spot on a different continent, and when that was happening the only life on earth was … well there wasn’t any! (That sort of thing.) Vanished Ocean: How Tethys Reshaped the World actually undoes that frustration by placing a huge amount of what you will ever encounter in your life as a person interested in the Earth and its History in a single unified processual context. Not all, but a lot of it.