18. Major Events in the Geological Theatre

Now today we’re going to be talking about some of the major events in the geological theater this is the second of three ways that we’re looking at the history of life the first was rather abstract it had to do with major transitions and with reorganization of genetic information units of selection things like that that was last time today we’re going to talk about how life shaped the planet and how the planet shaped life so this is a quick run-through of 4.5 billion year process and then next time we’re going to talk about major lessons from the fossil record so if we consider there are a lot of ways of trying to construct a diagram that will give you a feel for deep time and it’s not so easy I once did a kindergarten class where I took a bunch of kindergartners and I tried to get them to step off a hundred million years at a time or ten million years at a time I think I did 10 million years for the week it takes six steps and then meet a dinosaur and there are a lot of ways of doing this but this is not a bad one because it gives you a diagram that shows you about how much of the existence of the planet has been occupied by life about how much of it has been a story that’s mostly of prokaryotes in other words the about half of the time that life has been on the planet there have only been prokaryotes and about how much of it has been complicated multicellular organisms and of course we show up just briefly before midnight and that kind of a scale that’s one way of looking at it and learning to think about deep time is really important if you have a taste for macro-evolution and it’s certainly important if you have a taste for geology now at the beginning we had a reducing atmosphere and the source of o2 was photo was photosynthetic bacteria I’m just going to check something here okay so we start off with a reducing atmosphere and then we have to fill up essentially once the photosynthetic bacteria get going and and by the way some of them were were chemosynthetic as well as photosynthetic once the photosynthetic bacteria get going and start producing a lot of oxygen there’s a tremendous mass of stuff on the face of the earth that has to be oxygenated before there’s any free oxygen so that takes quite a while so until about half of the age of the planet the concentration of oxygen in the atmosphere was less than 0.4% you would all die within a minute and that oxygen concentration and the evidence that we have of when there was free oxygen in the atmosphere is essentially the age of the iron mines of the world so there was ferrous oxide you can dissolve in water floating around in the ocean and when the oxygen level of the atmosphere got high enough it oxidizes to ferric oxide and the ferric oxide fell out of solution and when it fell out of solution it made the iron mines of the world that happened 2.3 billion years ago this kind of process continued with other sorts of elements so we have copper coming out at about 1.7 billion years at a higher concentration of oxygen and the consequences of free oxygen are that an ozone layer forms in the atmosphere that screens ultraviolet light and that drops the mutation rate and it’s probably only because the mutation rate dropped significantly with an ozone layer that we could evolve large long-lived organism once you have oxygen in the atmosphere you can start getting nitrates nitrates are oxygenated nitrogen so you won’t really have nitrogen fertilizer until you have free oxygen and that then also became a key nutrient for algae so there’s a whole sequence of important chemistry that goes on over a period of about three billion years that starts to set up the environment that we’re familiar with there are number of ways of looking at this this is from Dante Marais at the Ames Research Center he’s an astrobiologist and is specialized in trying to examine the question of life on other planets and they have tried to make diagrams like this for other planets as well so in our early environment the Sun was only about 70% as hot as it is now and by about five hundred million years ago it was up to 95 percent the early environment of the earth was a meteorite bombardment so if you were out looking at the night sky which of course you wouldn’t have been able to do because the meteorite bombardment was so intense that you would have been standing on a boiling lake of lava but if you were out looking at the night sky and you’re boiling lake of lava in your Terminator suit or whatever you would have seen lots and lots of big meteorites coming in every night and that gradually tailed off okay the heat flow out of the molten mass forming the core of the earth has tended to drop off and stabilize so it has a continuous radioactive input but the original heat from the entire planet being molten has gradually radiated so we’re stabilizing at about the heat flow from the radioactivity in the earth and the continents formed and stabilized at about 1.8 to 2 billion years ago and these things called major or Raja knees are major chunks of continent coming up and major mountain ranges getting built now the collision of plate tectonics has continued to form mountain rages since then but this just stabilizing the continental crust took about two billion years if you look at the history of the atmosphere of course we’re currently worried about the cost carbon taxes and global warming and anthropogenic effects on the co2 concentration in the atmosphere but at the origin the co2 level was much much higher the atmosphere was more than what we would call a hundred percent co2 because it was thicker at that point and it blew off this is dropped down here to about 3 times 10 to the minus 4 atmospheric pressure for co2 it’s actually a small component oxygen rose and probably reached present levels at about five or six hundred million years ago it’s interesting that if it went off a little bit more a room like this could catch on fire just spontaneously at about 27 percent would will catch on fire spontaneously at current atmospheric pressures so this is another way of looking at that process at the beginning we had water hydrogen carbon monoxide lots of steam a lot of that escaped to space there were meteorite impacts the co2 curb has gone down the oxygen curve has gone up there’s some indications it’s gone up stepwise temperature we don’t really know accurately what the temperature was back before 3.5 billion years but we can be pretty sure that after the or at and after the origin of life water was liquid on the surface of the planet so that sets an upper limit of 100 degrees centigrade and temperature has gone up and down in a number of cycles over a fairly long period and there have been some major ice ages how do you recover that well one of the ways that you can do it is you can look if you have leaves of fossil plant so if you’ve already got plants that if you fall and they have leaves so maybe about the last 300 million years or so you can look at the stomata ratios on them so this has been calibrated plants have to make more holes in their leaves if there’s less carbon they have to have a bigger mouth so that they can feed more efficiently and they can have fewer holes in their leaves if and they can be smaller if there’s more carbon in the atmosphere and so basically this allows you to plot an estimate a curve and it looks like there was massive withdrawal of carbon dioxide from the atmosphere from the Ordovician through the Permian right here and then there was a reinjection here going into the Triassic and when we come to the Permian mass extinction I want you to remember this dip here and this reinjection and then there’s been a more gradual withdrawal down to the current level so the earth was much more of a greenhouse in the past than it is today if we look at where the carbon dioxide went a lot of it got locked up in limestone in sedimentary rock then a lot of it is inorganic carbon a lot of it is in the ocean as bicarbonate these are by far the largest sinks but there’s a lot of bicarbonate ion in the in the ocean this is all the fossil fuel on the planet right here so this is all the coal and oil and you can see that of the original amount of carbon that was in the Earth’s atmosphere that’s a pretty small fraction it’s a bit less than a thousandth of 1% and in living biomass there’s a very very small part so basically if you look at that you can see that the carbon balance of the planet is extremely dependent upon what happens in rocks and that if there are small geological changes in the in the cycle of how carbon is going in and out of rock and whether it’s being subducted is plate tectonics proceeds or not it’s going to make a much bigger difference to the amount of carbon in the atmosphere then the amount of fossil fuel that’s being burned or the tree cover of the planet in forests which would be the living biomass term down here however this is a slow process and this is a fast process so on the scale of human lifespans this is in fact more important but on the scale of say somewhere out at around a hundred thousand out into the millions of years what’s happening in sedimentary rock is really critical now if we look at the way that life structures the planet one of the very important things that life is done is that it’s made soil and we don’t really start to get soil which is a big complicated piece of engineered niche that plants create until we get complicated plants on land so the first ones on land are probably things like liverworts and and our first fossils or club mosses and that’s happening back at around 400 to 500 million years ago there are fossils soils and those fossil soils have roots in them and those roots suggest that the first time that there were real trees was at about 350 to 400 million years ago remember back to that clock this is this is relatively recent in terms of the age of the planet so we get really modern soils with layering and with evidence of seed plants in the Carboniferous so that is the age at which most of the coal mines of the earth were laid down it’s about 300 million years ago if you take interstate 80 west of New York and you go out to where it crosses from New Jersey into Pennsylvania at the Delaware Water Gap there’s a cut there that you can look up at and what you’re looking at is the outwash of rivers that were coming down off of the Taconic mountain range and if you look into that cut it’s remarkably clean it’s a preservation of what was coming down rivers 500 million years ago and it’s an indication that there was very little soil it is basically before at or before this process occurs and that mountain range was formed when Pangaea formed which is at around 550 to 600 million years ago and caused the Taconic orogeny and that put up a mountain range on the border between Connecticut and New York that was about as high as the Himalayas but it didn’t have any forests on it and it had a very high erosion rate because there weren’t plans to stabilize the soil and we can see in the Delaware Water Gap what washed off that mountain range it’s all worn down down and if we come back in another five hundred million years the tamales will all be worn down but with the Himalayas there will be a bit more soil in the outwash the guys that have really in the past engineered the planet and that continue to do so are the bacteria and by that I mean both the Archaea and the u bacteria they are the ones that play a huge role in the carbon cycle they’re producing an oxygenating methane they’re fixing carbon dioxide in the nitrogen cycle the bacteria are fixing nitrogen from the atmosphere they fix it as ammonia they oxygenate ammonia to nitrate the denitrifying nitrates to ammonia and this is a kind of biochemistry that just about nobody else has so these are essential things the nitrogen and all of the proteins on the planet is essentially originating through bacterial processes so that’s how it’s getting from the abiotic world into the living world there are sulfur bacteria that are arguably extremely ancient and which evolve an environment in which much of the energy coming into living systems was coming from things like sulfur rather than from sunlight and they oxidize hydrogen sulfide to sulfate they reduce sulfate to hydrogen sulfide and iron bacteria are converting ferrous to ferric iron and they’re influencing a degradation of manganese and copper deposits a lot of this is now going on at spreading centers at mid-ocean ridges or it is going on where there is heat flow which is taking ocean water through the ocean crust and they’re bacteria that are sitting just below the ocean that are sitting in a stream of basically hot chemical soup that’s coming through and when they do these reactions often they leave a metal deposit behind which is why the floor of the Pacific Ocean is covered with manganese nodules the people are thinking about mining at a depth of about five kilometers if you go down into the Earth’s crust it turns out that the biosphere extends below our seat several kilometers bacteria are active that far down into the soil and they are carrying out things like this so they are really key players in structuring the environment in which we live and they do a lot of services that we simply take for granted and frankly hadn’t even noticed until about the last hundred years or so okay so those are all aspects of how life has modified the planet how has the planet modified life well there’s at least three or four big chapters here one is through continental drift another is glaciation mass extinction and then local catastrophes and a continental drift and mass extinctions are both out there at the scale of hundreds of millions of years glaciation has two scales there are times in the planet’s history when it’s been relatively cold basically there have been at least three times when it’s been really quite cold but within those longer periods that are called the glaciers have come and gone many times so the North American glaciation lasted 2.5 million years and the glaciers came and went about 15 times in North America the local catastrophes it all depends on which particular kind that is you’ll see that they occur at different time scales the the point of all of this is that often the past configuration of the planet whether it’s the location of the continents or the temperature of the earth or whether you could expect to live in a secure environment have at times been extremely different from what we currently see and so it is not only important if you want to understand evolution to cultivate a sense of deep time it’s also important to cultivate a sense of different time sometimes deep time was really different and that’s what I’m trying to get at by showing you these things so here’s the last 400 million years of continental drift and by the way people are producing models that can now take this back to about all a billion years of course the further you go back the harder it is to reconstruct it because the continents have come together and come apart and come together and come apart in a long-term cycle several times and in so doing they kind of wipe out the traces of their history so it’s it’s really quite a feat to try to reconstruct it and I just like to point out a couple of things here this is Gondwana so Pangaea was a little bit earlier than this that was when all of the continents were together South America and Africa and Antarctica and Australia stuck together in India stuck together for a while before they came apart there is an interesting thing going on right here here’s New Haven if you go out to the lighthouse park in New Haven you’ll see some rocks there and if you trace where the closest relatives of those rocks are on the other side of the ocean they’re in Rabat Morocco okay so you can actually see the same kind of rock on the other side of the ocean and that’s when that happened that’s 250 million years old anybody know how old East Rock is east rocks 225 million years old when the Atlantic opened sea the Atlantic opening here there were a series of rifts that opened up one of which became the Atlantic another one became the Connecticut River Valley it didn’t open but it went part way and then it had a valley filling lava flow that filled it up and then the flow tipped and it tipped pointing west and it cracked in a number of places and that’s what it’s each Rock West Rock and all the other such formations that go up through central Massachusetts to southern Vermont that was a big while the flow filled up a big rift valley so that happened right here now when Gondwana split up it had some things living on it the rat tight birds and they are flightless and they don’t swim and essentially they got rafted around on pieces of rock and it’s interesting if you think about when Gondwana split up it indicates that the ancestor of these birds was already alive and living across that range of geography at that point and you can lay a molecular phylogeny of the ratites onto these continents and it just ties them right together okay there’s another thing that happened with the breakup of Pangaea Laurasia went north Gondwana went south in between for a while there was a thing called the tethoscape it’s about 50 million years ago in the Eocene by the way the Eocene was quite warm it was really a very tropical period and at that time there was either there was a warm kind of Mediterranean coastline that stretched from eastern North America through Nepal what is now Nepal into what is now eastern China this was before India rafted north and Africa came north and closed-off South Asia and this is what is thought to have accounted for some of the similarities in the plants that you find in the Appalachian Mountains and in China and there are many affinities here the rhododendrons viburnum there are a number of tree tree species that share a phylogenetic relationship across that huge geographical distance and it’s thought to have been the signature of a corridor along which seeds could move 50 million years ago now how about glaciers well here is a fairly deep time scale so this is the phanerozoic the phanerozoic is the term for everything that’s happened since since the Cambrian started so this is the phanerozoic here so this is about 500 million years this is about 600 million years and there’s evidence for one which is deeper at about a billion years so this is an ice age this is an ice age looks like there was an auto vision Ice Age looks like there was a Permian ice age and then there was an ice age just in the Pleistocene so about five ice ages interestingly this one which came before the Cambrian may have been a time when the earth was almost entirely covered with ice there are signatures you can find in the rocks of what latitude you’re at whether you’re close to the equator or not and there are other signatures you can find in the rocks that give you how cold it was these are usually in the form of isotope ratios for things like oxygen and carbon and stuff like that and at this point the entire Earth may have been a snowball and only the things that were very very close to the equator may have come through because if it really was a snowball then there was ice covering the world’s oceans that is an interesting issue and it’s one that will probably cause people to speculate and publish for quite a while because it’s so hard to resolve there’s not too much data it’s a long time ago the Permian glaciation however is much better study remember that in the Permian Gondwana is still together it breaks up at about 225 million years ago somewhere between 225 and 250 well the the Permian is at 250 about 251 I think and there was a southern ice cap that was on actually connected and actually these continents were all together and you can see from the arrows the direction in which the ice was flowing and I think it’s really cool that you can find rocks from Africa that were scraped off by the glaciers and deposited in Brazil before plate tectonics came along nobody had any idea how that could have happened and if you stand on the top of Table Mountain in Cape Town today which is something I recommend that any of you that have the opportunity to go to Cape Town do it’s really a very beautiful place you can still see the grooves in the rock from where the glaciers moved over Cape Town they’re two hundred and fifty million years old the climate since then has actually mostly been warm so this if you look on this set of maps this is 50 million years ago thirty five million years ago 15 million years ago middle of the Pleistocene about 1.5 million years ago and very close to today okay mid Holocene would be say about five thousand years ago and he looked at how much of the planet is temperate and tropical look at how tropical the Eocene was that was all tropical rainforest and the legacy was still there was still a huge area of tropics and the Maya scene still had pretty good tropics but at the last glacial maximum the tropics the tropical rainforests were reduced to a few patches we’re living today in a relatively cold relatively dry world that’s what we think is normal if we were to come in a polar orbiting satellite and look down at the planet say 20,000 years ago 30,000 years ago we would have seen that where we’re sitting right here is under probably about a mile and a half of ice the leading edge of it is pushing stuff off of the continent that becomes Long Island and Block Island and Martha’s Vineyard and Nantucket that’s the terminal moraine of this glacier Scandinavia and northern England are completely under ice as is the North Sea the Sahara Desert was humid you can go into the middle of the Sahara Desert and you can see rock paintings that humans made there where they’re recording hippopotamuses and things like that living in the middle of the Sahara at this time and we’ll see in a minute that the major tropical forest shrank so this is more or less the global pattern the gray now is ice the green is tropical forests the red is and and orange are excuse me the green is grassland the orange is rainforest so there are tropical forests refugia in certain places and if you were to go into the south what is now the South China Sea which is currently covered by water elephants and tigers couldn’t walk out over that because it was dry land enough water had been tied up in the ice to drop the sea level down that much and that is how they got to Borneo so they could actually just move down from Asia and get out as far as Borneo but they couldn’t make it across Wallace’s line there is a deep water passage there that Alfred Russel Wallace documented in the biogeography of Indonesia and they couldn’t make it to Australia or New Guinea so the sea level has gone up and down and that’s changed continental margins and the ability of things to move around in them so that’s impact of glaciations what about mass extinctions there have been two Biggie’s and Permian and n Cretaceous and at the end of the Permian not only the trilobite disappear but in fact the estimate is that 97% of all marine invertebrate species disappeared at the end of the Permian that is an extremely close brush with sterilizing the planet it came pretty close at the end of the Cretaceous the things that disappeared that we probably would like to have around to look at if we possibly could ammonites dinosaurs almost everything that lived on land that was bigger than five kilos went extinct and about 70 percent of the marine invertebrate species went extinct so this was a big one but the biggest was the Permian extinction so these are the trial of bites they were they had been around since the late Cambrian mid Cambrian too late Cambrian so they had been around for about 250 million years and they went extinct at the end of the Permian and these are ammonites in fact the chambered nautilus is fairly close to being an ammonite it would be sort of a modern survivor of this lineage so they were squid-like creatures that had curved shells and if we look at the diversity curve for so this is the number of families that you could find their most these are mostly marine invertebrate families okay so number of families of organisms this scale goes from the 0 up to about a thousand this is the beginning of the Cambrian right here this is the vendian and then the Cambrian begins here this is the Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous tertiary so this is the age of dinosaurs here this is the age of mammals here and you can see that most of the last five hundred and fifty million years of history is a history of marine invertebrates this is a mass extinction at the Ordovician this is a mass extinction at the Devonian this is the Permian mass extinction and this is the Cretaceous mass extinction the red is the modern fauna the green as the Cambrian creatures and the blue the stuff that originated in the Paleozoic so you can see that we still have almost all the Cambrian things are gone we still have we still have families of things that originated in the Paleozoic and what we think of as the modern creatures really started some of them started way back in the Cambrian but they built up a lot and the carboniferous and permian and then radiated again in the Triassic so what caused that B what caused that big extinction well Gondwana was breaking up and so laura larae sure was also separating from Gondwana so Pangaea was breaking up at that time there was large-scale volcanism and at that time there was a lack of oxygen in the oceans if you go to the Black Sea today this is the the Black Sea is sort of the model for what this ocean looked like the top Oh 20 meters or so over the Black Sea is oxygenated and has fish in it the Black Sea at its deepest point is about 2.2 miles deep and everything from 50 from 20 meters down to the bottom of the ocean is an toxic and it stinks like rotten eggs okay imagine the entire world’s ocean being in that state a very thin oxygenated clear upper layer and everything below it basically an anoxic no vertebrates can live in it it’s dominated by bacteria and it stinks like rotten eggs some people have suggested that there were extra extraterrestrial influences at the time it’s been difficult to find a meteorite crater of exactly the right age doesn’t mean there aren’t any absence of evidence is not evidence of absence but plate tectonics has remodeled the surface of the planet extensively since that and it’s quite possible that there was a big meteorite crater but it got subducted and it’s been wise it’s been erased so that we can’t see it at any rate you know this is a fertile area for speculation and people who thought of asteroids comets and supernovas that might have affected affected the planet at the end of the Permian it seems likely that it’s the breakup of the continents and large-scale volcanism but I can’t really claim that we really know what caused the extinction if you go to Siberia you can find what are called the Siberian traps these are among the largest flood basalt lava flows on the planet and they have just the right age they’re at about 251 million years and we know that the extinction of lasted not too long was a few ten thousand years it happened both on land and in the oceans and the organisms that went out in the oceans were the ones that were particularly susceptible to changes in the gas regime so that would suggest very high co2 levels so one idea is this there were massive volcanic outbreaks in Siberia that caused global warming that global warming then triggered the release of a huge amount of methane that was stored in the ocean okay this is this Black Sea like world ocean the methane then gets oxidized to carbon dioxide and essentially extinctions happen by poisoning and asphyxiation we do see a signature in the rocks that indicate that there was an amount of carbonate carbon that was oxidized at that point equal to several times the current biome the planet so carbon levels really dropped I didn’t I didn’t list it here but I believe that at the end of this process the percentage of oxygen in the Earth’s atmosphere is about seven percent well that’s as though I took you suddenly in an elevator right to the top of Mount Everest that’s hard to deal with okay and that that’s the hot that’s one of the more plausible hypotheses for the infirmary and extinction the Cretaceous extinction is at just about 65 million years ago slightly less 63 and a half 64 million years ago and we do know that there was a big meteorite that hit the Yucatan right at the right time it probably did trigger extinctions mechanisms aren’t completely clear it wasn’t necessarily the sole cause if that meteorite in the Yucatan could have set off massive volcanism in India and the reason is this the earth is a spherical lens and if you throw a big rock into one side of the earth the energy from the impact radiates out reflects off the walls of the earth and comes back together at a single point on the other side at that single point on the other side was focused into western India at the time that India was moving across the Indian Ocean before it hit Asia it was just in the right spot on the other side and that’s where those lava flows are and those lava flows have exactly the right date so there’s some reason to think that this might actually have happened if you go to the Hindu and Buddhist cave temples of the Western Ghats in India you will be in those lava flows they are massively thick and they cover a huge area so that’s not demonstrated but certainly the meteorite is well-documented it probably looks something like this so this is about a 30 kilometer wide meteorite it’s coming in probably at about a hundred thousand miles an hour and of course it completely fragments and sends up ejecta and since it’s hitting into a shallow sea it’s ends up a large tsunami a mega tsunami there is evidence in Texas and Oklahoma that the waves crossing the southern coast of the United States at that point were 1 to 2 kilometers high so big event and burning debris rains down across the planet if you go to Mexico now you can see the outer ring of the crater it’s a series of freshwater wells and the cracked limestone pavement of the Yucatan if you look with geological probes underwater you can see the rim of the crater this is a distance here of about 200 miles across it’s a big crater so this is Simon Conway Morris is reconstruction of what happens of course when the rock falls on your head everything’s killed right there there are giant earthquakes then within 10 minutes the rock falling out of the air ignites all of the forests of North America about 10 hours later tsunamis are pretty much covering the planet taking out anything within one kilometer vertical distance of the ocean probably the first extinctions of things that have a broad Geographic range are occurring within a week there’s a very very dusty atmosphere for about nine months and that induces a nuclear winter that lasts about 10 years we don’t probably didn’t go on much more than 10 years because the plants do not notice this event the animals get killed but the plants have a seed bank in the soil and the seeds can make it through so the plants don’t notice this event very much continental vegetation starts to recover takes the the planet is pretty much covered with ferns for about a thousand years but within a thousand years we started getting forests back and things like that then it takes the deep water in the ocean several thousand years to recover takes about fifty to a hundred thousand years for the oceans to become well oxygenated again it’s thought that the dinah some populations of dinosaurs some places in the world managed to go on for about another hundred thousand years before they all died out and that the ammonites the last ammonites went out about three hundred thousand years later and then you can see the rest of this going on took about fifteen to twenty five million years after the extinction to repopulate the planet to the level of biodiversity of had before the meteorite hit and that is an estimate of how long it might take the planet to recover from the current human caused mass extinction which is going to be roughly an extinction of the same size as a meteorite this is just a bit of evidence this is a section I’m not going to run through all of this I just wanted you to have this if you wanted to so you could see some of the evidence this is a deep-sea core off of the Florida coast and it marks the boundary between the Cretaceous and the tertiary and in this chunk of it right here are the impact ejecta so there is basically glassy tektite and globules and things like that and shop quartz in here and the iridium the famous iridium anomaly iridium is enriched in meteorites and pour on the Earth’s surface and you pick up a lot of that element right in here so this is the kind of evidence from around the world that indicates that this was a big event so that’s the end Cretaceous extinction and it seems to be linked to the meteorite and may not only have been caused by the meteorite there were also volcanic eruptions I now like to do a little bit of local catastrophe this is on a more frequent timescale just to convince you that sometimes on a shorter time period conditions are quite unusual so the major earthquakes I mean we’ve all experienced in 2006 the big tsunami in Indonesia there’s several of those per century we haven’t really had a volcanic eruption in our lifetimes that came anywhere close to Santorini or Tambora Krakatoa was much smaller than Tambora and these things cause tsunamis and global cooling then there are the gigantic eruptions eruptions that were occurring in the Cascade Mountains during the Pliocene would do things like drop clouds of volcanic ash onto wandering herds of woolly rhinoceros is in Nebraska 2,000 miles away and when the flue grain fields at Naples went up they dropped ash into Kiev in Russia the flue grain fields are still active and there were rather heavily populated suburb of Naples right now you know you have to have as a property owner you have to kind of wonder what you’re sitting on these come fairly rarely okay every ten thousand to a hundred thousand years then there are undersea landslides and these can produce really huge tsunamis so if the Nile Delta or the Mississippi River Delta or the Amazon Delta loses structural stability and slough off into deep water dropping cubic kilometers of sediment at one go you get a very big tsunami I’ll show you one in a minute and then there are super floods and we’ve had some of those in eastern Washington they’ve occurred in Siberia in Manitoba they happen at the ends of ice ages when the glaciers are melting so here is an example of a mega tsunami and this is what happened when the west coast of the island of hawaii fell into the water about 125,000 years ago it dropped the chunk of rock that was probably about 20 kilometers wide by about 1 or 2 kilometers deep by about 8 kilometers high onto the floor of the ocean and by the time it had gotten this far it was moving 500 kilometers per hour and it shoved blocks of island that were about one kilometer long out in the deep water about 200 kilometers away and that’s just about the right and velocity in that depth of ocean to entrain a tsunami and this is a geological model of how high the tsunami was so the landslide is here and then the tsunami goes out it actually goes well up into the top of Lanai here this is in meters so when you start getting red you are up at a thousand feet above sea level the highest point of the run-up of this tsunami was right here kind of it went up 2,400 feet according to that and there had been previous ones other pieces of Island had fallen off at various points there is a ring of coral that goes up to about 1500 feet elevation right here from an earlier tsunami and perched on top of the island of Lanai is a lake of seawater that was deposited on top of the island by a mega tsunami so sometimes the surf is really up these are big waves this is a recent volcanic eruption just to show you what it will do this is pumping an awful lot of ash into the atmosphere this is a 22 kilometers elevation and this actually caused global cooling and beautiful sunsets for a couple of years and then these are the super floods of Eastern Washington that went down the Columbia River about a kilometer high and took an awful lot of the soil of Eastern Washington off and that’s what happened when a giant lake suddenly caused a glacial dam to burst and the flood went out okay this is the kind of a boulder that could be easily moved by a flood that side so basically the idea of this lecture was to show you that life changed the planet and mainly it was bacteria that did it that the planet and the extra-terrestrial environment have had occasional major impacts on life this big picture view this macroevolutionary view describes a world as really qualitatively different from our normal experience and we’re going to reconstruct what happened to some of those things next time in the fossil record

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