Transcript for:
Earth Environmental Science - Module 5 Overview

hey guys welcome back so this video is going to be an overview of module 5 for Earth environmental science now if you did it last term for the first time and you went into just clarify a few things I hope you get up to speed after the holidays have a quick watch of this video and have a crack at the questions that will be provided at the end so to start with let's look at what we should have covered okay so the origins of life on Earth was up for debate for a very very long time because a lot of people were still operating the under the concept of cell theory which is that life must come from lifeless matter so if that's the case where the first life began now the Yuri Miller experiment is something you might have covered in biology whereby doctors Yuri and Miller tested to see whether the basic building blocks of life could have occurred in the natural circumstances of our planet so as you can see in the diagram here we have water vapor that's been heated up and it's been mixed with methane ammonia and hydrogen gas in the presence of an electrode so this is meant to represent some of the key materials that were present along with the energy requirements that were there now in doing so there was also condensed afterwards and chemically reacted using cold water here and any organic material would have fallen out at this point whereas the normal water would have continued onwards now at this point we're also considering that you know there was a lot of water in but also pumping in new water or they might have put a filter there now meteorites as coined to these notes Here were also a very big portion of what helped create life because they provided unique materials that Earth didn't actually have remember Earth is a spherical shape floating in space now Earth will not gain or lose Mass unless something actually makes it up and out of the atmosphere very lighter than our Gases such as hydrogen gas or helium might naturally bleed off of our atmosphere also any material that we launch into space such as space shuttles or rockets that you know have payloads they go out into space or satellites and actually going to help our planet over time shed very minuscule amounts of matter to contribute that we have to doesn't mean coming from space to hit Earth such as meteorites now originally they also thought that panspermic theory or panspermia was a possible Theory whereby life traveled on a meteor from another planet landed on Earth and was like a seed it started to grow so that means that all life wasn't actually indigenous to Earth but rather came from somewhere else now over time the Yuri Miller experiment became more of an accepted Theory aspermic theory is incredibly unlikely consider how big space is okay now I've also consider the circumstances that would allow life to end up on a meteor floating through space and the odds of it landing on Earth Occam's razor which is you know the simplest answer is often the most correct one would state that the Yuri Miller experiment is much more likely whereby we already had materials here it was just a matter of time for the right components to be combined together to create amino acids now down the very bottom here we also have some information about hydrothermal vents now these hydrothermal vents responsible for kicking up various materials that were found only beneath the crust into the bottom of the ocean now some of these materials such as black smokers and white smokers were incredibly hot and they also produce materials such as iron copper sulfate calcium and barium sulfate while some of them are crucial to life the sheer temperature around it doesn't actually make it likely that life could survive there extremophiles today can survive but not necessarily those whereas in alkaline hydrothermal vents was only 60 degrees harsh but not unbelievably hot and produced tons of materials so these alkaline ones would more likely than not help with creating the building blocks for life now photosynthetic life came a little bit later on now here we have what's known as a stromatolite stromatolites are essentially a pillar of layered bits of organic matter and growth that's been growing over time so as we can see the top of the head is what we call Supra title which means it's often above tidal flows now these things only occur in areas where the tide comes in and then recedes back out so these just stromatolites are estimated to be 3.4 to 3.5 billion years old and each one of these layers has crucial information about conditions that might have occurred during those three and a half billion years now the terms here super title intertidal and subtitle refer to whether it was above semi above semi below or below water currents that came through okay now over time each layer of these stromatolites had discreted matter coming out the top so on the very top we had microbes well my photosynthetic microbial activity or colonies these columns would produce waste that they would shove underneath them and as such over time they would build up a layer then the rest of the micros would grow on top of that and then create more waste so it's like it was building a ladder as it was climbing it now what makes us unique is that because these stromatolites were photosynthetic they could dictate how much energy they need in order to produce how much waste so it stands to reason that if we know how much sunlight was reaching them we could estimate aspects of the the atmosphere and how much other material was present such as carbon dioxide in the atmosphere and water in the atmosphere so cyanobacterium is essentially like a full cell that's served as a chloroplast to give you in layman's terms imagine a cyanobacterium as one of the oldest computers that you've ever seen okay it's big it's boxy it takes up a whole desk now a current chloroplast is like your iPhone it's smaller but it's much more advanced it's much more efficient now over time these stromatolites and the cyanobacterium were major contributors into helping oxygen reach into atmosphere and it's a really important aspect so the cyanobacterium helps to alter this composition or atmosphere so in the very early days so 4.6 to let's say around by here we had huge amounts of methane water hydrogen helium gas and carbon dioxide but with the presence of cyanobacterium and stromatolites that they grew on we can see there was a dramatic change because carbon dioxide and water are both used in photosynthesis so if life started taking all this material from the atmosphere then there's love is going to go down but in turn what happened was we had an increase in oxygen we call these oxidation events or OE and these are crucial because they allowed our atmosphere to sustain organisms like us if we were to go back three and a half to four billion years ago we need to have a specialized suit in order to breathe properly because we couldn't breathe the natural air that's there now on this graph we can see the amount of oxygen that's formed in the atmosphere we can see that it goes up and down based on events that occurred in our planet so around 600 to 800 million years ago we had a Neo proto-zero proterozoic oxidation event so this is associated with global cooling now if we know that creating huge amounts of CO2 in our atmosphere caused the atmosphere to increase in temperature then stands the reason then if the CO2 levels go down but oxygen goes up then it creates a global cooling event and this has resulted in a natural cycle of global warming and global cooling which has remained undisturbed for a long period of time until humans started developing new forms of technology now here we have a modern microbiliates which is post cyanobacterium so after cyanobacterium began to develop you know we can see that there's a huge increase in oxygen now eventually cyanobacterium would be outsourced by other forms of bacterium such as eukaryotic algae and then eventually development of plants which is much later here the first dinosaurs we can see this is a small decrease in oxygen because they're consuming it so multicellular organisms are a big deal because back in the day when we had say your cyanobacterium whoops here a lot of the earliest forms of organic life were very simple okay they were not designed to be incredibly complex or articulated they simply it works don't change it but due to the sheer numbers there's something to change conditions so in turn life had to change as well the first evidence of a multicellular organism is actually a plant called a bangus Morpher approximately 12 1200 million years ago now eventually animals are going to form when we started having CO2 or decrease and O2 level increase to the point of which it could sustain us now a big term down here is bilaterally symmetrical animals recognize today Diversified and became well established so bilaterally symmetrical means that if I were to split an animal down the center and look at either side they'll be relatively the same there are very few animals where you cannot do this with okay so say for instance that you have a horse one side of the horse is not going to be mustier than the other side of the horse okay there has to be at least one axis where if you cut in half each side would be relatively similar now this means that it was an advantageous trait much like how the pentodactyl limb is a trait that was very advantageous if both signs are symmetrical then it means that they can walk in they can go in a straight line and they're not going to be compromised they're not going to start going around in a circle because one side's super muscly the other side's really weak okay or they're not going to be at disadvantaged like both eyes are on the left hand side of the head makes no sense because your massive blind spot here around about 523 million years ago some animals when they achieve larger sizes began an evolutionary arms race they started developing armor teeth and eyes and at which point this Predator prey relationship actually started to kick off before then every organism was just struggling to survive but 523 million years ago they were so good at surviving that they started to compete with each other over natural resources all right so in here we start to look at some really old pieces of evidence so plants 470 million years ago arthropods Ford and 14 million years ago tetrapods 365 million years ago Evan suggests that they evolve from aquatic species and gradually transition the land taking two to ten million years the reason why it took so long is because inside an ocean most of the abiotic factors such as temperature and access to oxygen was relatively stable on land they could fluctuate wildly for instance if you go into the desert it can drop down to -15 at night during the day early early 40s so it's a great range inside of the ocean right about 20 to 30. degrees really really stable the plant colonization of terrestrial environments During the devonian period assisted in stabilizing rocks by soil by root anchoring to bedrock stabilizing soil profiles which enabled thicker profiles to form so before then you'd had really exposed you know parent material and not many Horizons now when you started having Roots attaching they were able to help break down more of the parent material and the regolith that formed just stayed where it was so it started building on top of it okay so after the devonian period we actually started having soil that could not just be a result of weathering but contribute to plants being able to survive longer this helps in reducing erosion rates with the soil profile with the roots involved they could you know increase more parent material to be weathered to create more soil and minimize eroding factors so it was less likely the soil was just going to get washed away and wasted now here we have land organisms so I'll just move this over here other top here we have the camber Imperial which is the earliest form and as we go down to the orovision silurian Carboniferous devonian and Permian periods we can see that if you read the traits that they become more complex over time so in the Cambrian Period many of the Primitive animals were just sponges but as we go down they start to develop bones they start to develop articulated limbs they start to have massive deposits turned to Coal that's beneficial for us as humans obviously but it's not developed amphibians which would colonize on land right about the Carboniferous period like the first fish that came out of water might have been a lung fish or some something similar now eventually get down to the Permian period here we had organisms that could withstand extreme temperature variations and they are able to you know consume other matter in order to feed themselves and they could retain any water they got from the food they ate so for here they say that that plants had waxy leaves animals had leathery skin made it more difficult to lose water due to transpiration or sweating over here we can see that a lot of the organisms that started out only based around Salt Water because they start in the ocean but then over time they started to develop in fresh water then in areas where they had high amounts of sunlight then they had something that could sustain self-drained drought and then finally here things that were only based on land all right now the evolution of the biosphere so our biosphere evolved over time it started off with a lot of organisms that were similar and then the number of very variations of species the number of different types of plants and bacteria and fungi and animals exploded in what became known as the Cambrian explosion so here we can see there's a relationship between our geosphere and the biosphere over a long period of time so when the early oceans be in the form we start having proto-organisms when we had very little to no free option most life actually formed and only lives in the oceans but over time when the oxidation event occurred we started having more variation of plants and almost like a survive on land now here in this table we have different areas of you know C first plant animal well first land plants devonian and then finally living planets and what kind of materials they require known to survive so Cambrian green algae often required brackish water which means the combination of fresh and salt water so any sort of estuary or a delta or a mangrove swamp that's located on the coast is where most of this would have survived that sort of region but not with the amount of protection that those mangrove swamps and trees and plants and everything provided tectonic super cycle now in junior school when you looked at Continental Drift you would have become familiar with Pangea or Pangea different ways pronouncing it all of them are the same as long as you spell it right it's all good now this occurred in the premium period about 250 million years ago and it was part of what became known as a plate tectonic super cycle where in essence all of these different consonants would constantly drift around and merge then split apart and then merge again very very slowly other superconds I might have exist before then include Pinocchio rodinia Colombia and Canada land the Pangea one is famous because you know it would have been the period where dinosaurs were roaming the Earth 250 million years ago and as such a lot of the earlier fossils that we found dinosaur bones would have indicated that Pangea actually existed so we can see here that Pangea split up into Eurasia and gone wanna land for us in Australia So Gone wanna land was where Australia was located now in during the Jurassic period we can see it splits even further so we have Australia over here and it's splitting off from Antarctica Antarctica moved further south Australia moved out away from the others and as such we'd start developing our own unique biosphere because we as Australia are primarily cut off in a lot of other continents now because we're cut off from these consonants most of our plants and animals were evolving and changing undisturbed from other factors if you go into Asia Europe and North America they all have some variation of bear or they might have something like a tiger like if you compare say India Asia and South Africa well sorry Africa not South Africa all of them had very large cats Australia doesn't so Evolution climate and the super cycle so here we can see that the plate tectonic super cycle was capable affecting other factors as well so let's say you had one massive supercontinent in doing so you have less exposed Coastline compared to if you have multiple consonants because of this there was more C or there's more ocean exposed to the surface so sea level was at its minimum it was lower however if you broke it apart and there was more coastline Waters would rush in and it would increase because you know it was more land taking up more space the climate decreases when supercontinence form due to Marine sediments absorbing CO2 and polar ice sheets reflecting solar radiation so if we wanted to you know snap our fingers and solve climate change maybe we could make another suit and continent by just slamming back all together that's all production rifting causes CO2 release and Greenhouse conditions bath salt is often a result of seafloor spreading so to plates split apart name it comes up through calls when it reaches sea water forms basol then they move apart again and cracks forms more evolutionary events linked to supercondent formation include proliferation of cyanobacteria appearance of metazolans and evolution of skeletons and supercontinent drifting creates new habitats and leads to adaptive radiation of species adaptive radiation indicates that means that when you have a species and begins to create much more variation okay it spreads out the differentiation of all individuals within a single species so that there's more likely a chance that a small percentage of that species Will Survive and then pass on their genes and help that species evolve overall so here we can see the general process so we start with something that's relatively stable we have a sag Basin can form a rift basin so we have material that's heating up underneath young passive margin passive mature margin Oceanic subduction so essentially if the moving part imagine separating hot dough okay if we're pulling it apart it thins at the center and eventually it will begin to drift Parts point of which it splits all right fossil formation now there are different types of fossils based on what kind of conditions are present and what type of animal or plant or whatever there was so for the most part fossil formation only occurred in sedimentary rock because it had the conditions there to preserve them metamorphic and igneous are exposed to such heat and pressure that it will destroy your organic material in there and distort it now for the most part if they're condensed and there's other materials there that don't help preserve it it results in creating what we call fossil fuels but let's say for instance that we want a perfectly preserved fossil there are at least six different variations we'll have a quick look at them we have trace fossils which include stuff like Footprints Burrows anything that indicate that an animal was there mold and casts so it could be an impression of something so it might have died the animal you know laid down in a mud pit passed away over millions of years the animal didn't survive it was remains didn't survived they were destroyed but the impression that it left in the stone underneath it survived a replacement is where the organic material the original material of an animal is slowly being substituted with something that's inorganic so imagine a skeleton that has slowly been taken over by inorganic crystals that form inside it but it retains the original shape petrified or per mineralized empty pore spaces are filled with minerals such as petrified wood Amber it's very similar to say original material except it's much more specified the fact it's preserved in ancient tree sap modification of freezing similar but over time that one is more likely to suffer from degrading so if we have say a mummy if we're to be rehydrated and then desiccated again it will be severely warped and damaged much like if you throw something and then thawed it and then froze it again it would become more damaged over time same reason you don't force something from your freezer and then re-freeze it again because odds are it'll be altered after it's been thought out now rapid burial is crucial as it helps provide an anorexic environment exposure to air is one of the most damaging things that can happen to fossils and remains like these so if it's been entombed in something like tar or Amber or ice or tree sap or volcanic ash it does really well I mean look at Pompeii we have stuff there that's been perfectly preserved for thousands of years a couple of thousand years if it's in bed and sediment then there's a chance of material can undergo petrification when livification occurs on the surrounding soil horizon so it would say stuck in say mud and then over time that mud was begin to turn into stone through petrification then that can alter the fossil itself all right index fossils now let's say that you've dug approximately 10 meters down now when you've dug that far down you've found a particular seashell this seashell might only be found at this particular depth because that is when according to the law of superposition it died and was starting to be buried into you know layer upon layer of look of sediment soil now index fossils are known for having a very distinctive start point and end point and they only occur within that range so this means before that time period before the start point they didn't exist as a species after endpoints they were all extinct there was no more left now if we know a very narrow band for this index fossil and we compare it to another fossil we can say this did not occur at the same time as that or these both occur at the same point in history because that index fossil would have been dated very thoroughly so we know exactly at what time period it actually existed then from there we might be able to say it was two centimeters long than this one so that might mean it was a couple of hundred thousand years beforehand now they do serve as very good benchmarks however index fossils are very great as relative dating which means they're not going to be super accurate if you're comparing something to an index fossil it's a great ballpark figure but then you go on to doing you know your actual dating all right dating fossils now there are two terms that people often use when they're looking at fossils one the present is the key to the Past so what we know now comparing it to what happened then okay we can use what evidence we have currently with us today to help unravel past events a lot of paleontologists a lot of geophysicists a lot of people who study all these ancient samples will use current evidence and understanding of how things operate to reconstruct how things happened a long time ago then from there we have the second phrase the past is the key to the Future if I threw my keys to you right now and someone took a photo of it as they were directly in the center of the arc these keys to the present I understand that they can't move on their own and they need a form of propulsion so I can extrapolate backwards to me with my outstretched hand after I've just thrown them indicating that oh he must have used his hand to provide propulsion to make them go into the air that's the first statement the second statement the past is key to the Future I know where my hand is I know where the keys are I know how gravity affects an object in Flight Ergo I can predict where it's going to land it's very similar to Benoit blanc's gravity's rainbow okay we understand the logical regression of events so we can predict what's going to happen next now with this we can combine aspects of stratigraphy superposition and uniformitarianism so we can have an idea of where our current conditions will lead us however for the most part throughout the Earth's history they haven't experienced human interaction so this might not be entirely accurate so here we have some very important events a geological boundary between the phenerozoic and Cretaceous periods due to presence of radically different fossils before and after the boundary the reason why this might be is because at the end of Cretaceous Period we know there was a massive extinction level event okay dinosaurs wiped out Cretaceous paleogene and Permian Triassic Extinction events will document thanks to stratified stratigraphic positioning and radiocarbon dating of volcanic material anytime we had a massive supervolcano erupting or we were able to you know have a meteor hit the earth and it kicked up tons of Ash and dirt and sust and certain whatever it would leave a very thin layer inside the stratigraphy of a given piece of Earth material from there we can determine whether something was after that event or before that event the Cambrian explosion was dated due to sudden the presence of cited shelled marine animals appear in the fossil records again the explosion doesn't mean it was an actual you know explosion explosion but a rapid increase in the number of species of organisms present so here number of sighted and showed marine animals just went through the roof so according statistics it was an explosion towards the southern camera explosion there was fossil evidence of large Vermilion animals and sediment just adjacent to sterile sediment so beforehand there was nothing in that sediment there was no sign of Life afterwards lots of it so if you're comparing a campfire to explosions a campfire gradually uses fuel okay and it slowly Burns over a long period of Time Explosion rapidly uses fuel in a very short instance so here number of organisms rapidly expanded compared to just gradually expanded circondating of volcanic crystals adjacent to Cambrian layer ports camera explosion approximately 540 million years ago very important information to know about a secondary explosion is one thing that's always brought up in stuff like this in this particular topic all right that's the end for the video for today if you have a chance what I'd like to do is along with the stuff that's covered in this video and stuff that's in your own notes have a crack at these four inquiry questions okay these are the type of things that exams particularly HSC exams and trial exams are based around okay if you cannot answer these questions and provide evidence to support your answers then clearly you need to go back to these topics and re-examine them all right so for each of these questions they could be a complete discussion question easily about one page all right have a crack at writing these all right ensure that you're using steel or peel paragraph structure ensure that you're able to you know create a basic report style when you're doing this and if you need to go in and see your Earth and environmental science teacher or you know talk to someone else in your class and show them what you've written if they have questions about it that you can't answer that might be something to just jot down in a different colored pen on your piece of paper to help you out all right as always I've been furry you guys have been amazing if you have any questions please ensure to leave a comment in this video or any future requests and I'll see you in the next film all right peace