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Post by alanw on Aug 9, 2012 20:14:49 GMT 12
Don't have to wait that long. After the current sea level rise it will drop after the next ice age kicks in so theoretically the Strait should be narrower. Unfortunately the sea level won't drop enough to close the Strait because of deep canyons that run through it. Maybe the 'wet' distance between the North & South Islands will be enough to enable a bridge to be built between the two Depends on what you term relative to 'Wait that long"? In Geological time, yes a tiny time period, in human terms we could be looking at up to a Millenia or more. The term Ice Age is really indicated by the volume of ice on the poles/Glaciers, which currently are still quite large. The fact that they are melting, is certainly indicative that the Earth is slowly warming (naturally and with some assistance from mankind IMHO). I recall one of my Lecturers at Flinders (either Oceanography or Hydrology, can't recall which ;D), stating that the Earth was still in an Ice Age, and this was indicative of the amount of O 18 (an Isotope of Oxygen) in large amounts in the current oceans. (I'm not that old, so not sooo long ago) Simple and dirty explaination, when the Earth is not in an Ice Age, larger amounts of normal Oxygen in the oceans, lesser O18. When any Ice Age begins, normal lighter Oxygen through evaporation is deposited in Water vapour in the Icecaps/ Glaciers etc, leaving more and more heavier Oxygen (O18) in the water (obviously the ocean levels drop also). I don't think we'll have to worry about the Ferry ticket rise anytime soon, we're looking at again many millenia, before any major transformation of the curret New Zealand map occurs. ;D Our decendants won't be so happy. ;D
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Post by ngatimozart on Aug 9, 2012 21:36:40 GMT 12
Things are to warmfor an ice age and not enough ice cover or more correctly the chyrosphere is to small for an ice age. From some of the literature I read a while back it is suggested that Antarctica may initiate ice ages and that we are nearing the top of the climatic temperature curve that has preceded previous ice ages (excluding the LIA). That has been the cycle for previous ice ages. What is different with this one is human induced climate change and I would argue all we've done is accelerated a natural process. However that acceleration is having negative effects for humanity and other life forms on the planet.
I wasn't really thinking about geologic time per se for my suggestion about the bridge over the Strait. Speaking of which I've seen an argument that suggests that we are now in the Anthropocene. Anyway if I remember correctly the ice age cycle is around 30,000 years and as I have said we are at the top of the cycle. That literature I referred too also suggested the change is quite quick. So as the chryosphere expands and ice sheets form, expand and thicken they depress the land and reduce the sea level as well due to uptake of water forming sea ice and the water cooling increasing the density of the sea water reducing its volume (water volume changes with temperature and its at its densist at about 4 degrees C). I haven't got the actual references handy.
I agree our descendants won't be too happy but by that time they should have adjusted.
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Post by alanw on Aug 10, 2012 10:37:59 GMT 12
One of the things I learned very quickly at Uni was that even two of the same Phd's in the same school may not agree on a given subject, I recall studying some strata on a field trip and the two lecturers gave both differing accounts on how, what we were looking at had occured and quite open about their variances.
Same for Global warming and the Ice Age.
Bare in mind that you can have warming seasons within an Ice Age even whilst the Chryosphere may contract some with minimal Isostatic readjustment.
I however believe that we are at the waning edge of the Ice Age, Greenland still has a large covering of ice (though that has shrunck in the last 30 years), and Antartica still has a sizable ice sheet also.
Factors which show (to me any how) that the Earth is warming up is Glacial retraction, ocean levels rising -slowly - note the levels rising need to be slow otherwise there will be some parts of NZ that will disappear quickly
The temperature even within NZ has risen over the last 80 odd years to the point where in my fathers day he could walk to school in Auckland and puddles had frozen over. Now you won't find that, we are lucky to find decent frosts in the metropolitan area (city thermal signature can affect that). Yet recent (year or two ago) temperatures according to some Climatologists have been colder - go figure.
Mankind needs to bear in mind this is the first time any off us have gone through this phenomenom, and we really don't know what to truly expect -Paleological sample analysis granted, will only answer some of our questions. None of us were around prior to 2.5 Million odd years ago when the current Ice age began to record changes in the Earth ;D
Isn't this the que for the Orwellians to chime in?? ;D ;D
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Post by kiwithrottlejockey on Aug 10, 2012 11:38:53 GMT 12
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Post by flyjoe180 on Aug 10, 2012 11:53:52 GMT 12
Thanks for that article link kiwithrottlejockey, very interesting. Volcanoes and earthquakes are intriguing.
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Post by kiwithrottlejockey on Aug 10, 2012 12:43:01 GMT 12
Thanks for that article link kiwithrottlejockey, very interesting. Volcanoes and earthquakes are intriguing. You will probably find the following video from GNS Science really informative... Or CLICK HERE to view the video clip in a larger-size format.Also THIS PAGE on NASA's Earth Observatory website.
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Post by flyjoe180 on Aug 10, 2012 12:54:47 GMT 12
Thanks again.
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Post by htbrst on Aug 10, 2012 13:54:08 GMT 12
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Post by ngatimozart on Aug 10, 2012 14:33:25 GMT 12
Cool thanks for the links. Quite interesting.
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Post by kiwithrottlejockey on Aug 11, 2012 1:52:04 GMT 12
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Post by Dave Homewood on Aug 11, 2012 10:58:50 GMT 12
One of the things I learned very quickly at Uni was that even two of the same Phd's in the same school may not agree on a given subject, I recall studying some strata on a field trip and the two lecturers gave both differing accounts on how, what we were looking at had occured and quite open about their variances. I took a university geology class and basically it taught me that you cannot trust geologists. Our lecturer was a nice lady but didn't like to have her thinking challenged. One day she was showing us a chart of all the layers of the earth and the earth's centre which she was saying was molten magma, etc. I was a bit puzzled as to how scientists knew all this. So I put up my hand, and asked. She didn't understand my question, so I said "Have people been down into the depths?" No. "Have geologists drilles all the way down through the layers?" "No", she says "That's impossible, we can only drill down x-amount." "But you're telling me that way further down from x-amount there are these different layers, which no-one has ever seen, sampled, gotten pictures of, etc?" "Yes." "Well then, how do you know this?" "What?" "How do you know that all this stuff you are standing in front of the class and telling us as pure facts even exists, if no human has ever seen it? Her answer, "We just know!" "Oh ok, so it's like religion then, it's in a book so you believe it is fact." At that point she got ratty and changed the subject. I guess she was religious. I absolutely hate it when scientists present a theory as a known facts, it's just wrong.
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Post by alanw on Aug 11, 2012 12:21:46 GMT 12
One of the things I learned very quickly at Uni was that even two of the same Phd's in the same school may not agree on a given subject, I recall studying some strata on a field trip and the two lecturers gave both differing accounts on how, what we were looking at had occured and quite open about their variances. I took a university geology class and basically it taught me that you cannot trust geologists. Our lecturer was a nice lady but didn't like to have her thinking challenged. One day she was showing us a chart of all the layers of the earth and the earth's centre which she was saying was molten magma, etc. I was a bit puzzled as to how scientists knew all this. So I put up my hand, and asked. She didn't understand my question, so I said "Have people been down into the depths?" No. "Have geologists drilles all the way down through the layers?" "No", she says "That's impossible, we can only drill down x-amount." "But you're telling me that way further down from x-amount there are these different layers, which no-one has ever seen, sampled, gotten pictures of, etc?" "Yes." "Well then, how do you know this?" "What?" "How do you know that all this stuff you are standing in front of the class and telling us as pure facts even exists, if no human has ever seen it? Her answer, "We just know!" "Oh ok, so it's like religion then, it's in a book so you believe it is fact." At that point she got ratty and changed the subject. I guess she was religious. I absolutely hate it when scientists present a theory as a known facts, it's just wrong. So Dave, did you ever get an answer to your question of how do we know the Earths core is molten? If not I can give you one (which is truthful). In reading your comments, I got better answers from my High School Geology teacher on the make up of the Earth's inner secrets. I guess I was quite lucky, in that all my Earth Science lecturers were quite happy to discuss things, though having said that, I do recall that there were certain things that they were die hard in. One thing I enjoyed was that my Lecturers would challenge us to learn and know, not just spout verbetum. Regards Alan
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Post by Dave Homewood on Aug 11, 2012 13:09:10 GMT 12
Nope. So my understanding at present is because no-one has been down there, nor has any probe or drill, it's all just a guess.
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Post by alanw on Aug 11, 2012 13:57:08 GMT 12
Nope. So my understanding at present is because no-one has been down there, nor has any probe or drill, it's all just a guess. Hi Dave The reason we know the Earths Outer Core is fluid is because of Earthquake waves believe it or not! (Sound like a Ripley's show) In the 1940's and 50's Scientists measuring Eathquake waves discovered some anomolies in waves travelling through the Earth. We now know Earthquake waves are divided into 3 types 1) Primary Waves (P) - These can travel through any medium (solid/liquid) 2 Secondary/Shear Waves (S) These can only travel through solids 3) Long or Love Waves (L) travel over the surface of the Earth and are primarily responsible for destruction Scientists discovered that the S waves would only exit the Earths surface at certain intervals/angles, while the Primary waves would occur all over from the focal point of the Earthquake. So accordingly they conducted tests to figure out why. It was after these tests, they came to the conclusion because of the variances/angles that the S waves exited the Earths surface that they were bouncing off at least the outer core, that was made up of a fluid rather than a solid. Also Scientists found that though the P waves can travel through all mediums the fluid medium seem to cause some refraction (bit like light and water) and were able to measure these refractive indices We also have come to know that the Earths mantle is a semi fluid which allows convection type currents to rise and fall (which is why our continents can travel around). The S waves do travel through this with some refractive incidence, but when the S waves arrive at the outer core the greates refraction takes place. Thats pretty much a nutshell type explaination and a lot more involved than what I have given here, but hopefully will answer your question? ;D Regards Alan
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Post by ngatimozart on Aug 11, 2012 15:56:38 GMT 12
Nice explanation. But thats what uni education is about Dave learning and stretching your mind. It's a bit hard for 1st years but everyone has a bias and their favourite theories which they will hold to even sometimes in face of overwhelming evidence against them. Sounds like your 1st year geology lecturer needs a kick in the arse and should remember if it wasn't for students she wouldn't have a job. Some are very egotistical and the politics within a department, let alone a campus, can be diabolical. Then there is how they perceive themselves in their field and I personally have had experience of some with huge egos.
I found that doing my geology and geography undergrad papers some lecturers held stubbornly to beliefs regardless especially if they had a social science background & regarded all science as evil. However their were others who actively encouraged questions and debates. I remember one field trip myself and a certain professor vigourously defending the flat earth concept just for the hell of it. He was a geomorphologist and we were doing some damage to a bottle of whiskey at the time. I was an adult student and it was great fun winding the young ones up. The young ones couldn't figure out how us old fullas (I was in early 40s at the time) could sit up all night drinking, be the last to bed and first up in the morning for hot showers and a cooked breakfast ;D ;D ;D ;D ;D ;D
That is why I liked 3rd year and postgrad because you have the freedom to research and explore. After my 1st year at undergrad I quickly figured out a bit of originality in things like essays etc., made for a big difference because I went out of my way to find a different approach and support it, instead of just regurgitating what was given in lectures etc. It was a bit risky but if you have 1 person marking 100+ essays then they get sick of seeing the same material with the words in a different order.
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Post by Dave Homewood on Aug 11, 2012 18:06:10 GMT 12
Yes I was doing a first year paper, and only as a filler paper that had nothing to do with my actual study, and I had no real interest in geology at all but had no options due to timetable, etc, but to take it - ie a waste of my time and money by had to do it because that is how the university system dictates it...
I seemed to be the only person in the class who had not done geology at school as everyone in the class had full understading of nearly all the terms and theories being talked about and I was basicly lost every single class. I had never been the doongy of the class before in my life, I was usually on the other end of the scale so it was not a nice feeling.
Hence the reason for my naive but pertinent question, which never received a straight answer, only "Because we know".
Thanks for your description Alan, that is more than Igot from the 'experts'. But I still feel till someone has been there and seen for themself it remains theory, surely. Standing on the suface firing soundwaves at the ground and looking at the result is not as tangible as digging a big dee whole, and the latter - as in so many cases with science over the decades - may result in overturning this wave theory.
I went right off the whole paper because of various reasons and very nearly dropped out, I was close to not bothering doing the exam, but my mate talked me into it and I somehow managed to pass, more through logic and guess work than actual knowledge gained in the paper.
Though in many ways the university education system is fantastic for stretching your skills and knowlegde, in many other ways it is flawed badly, and having lecturers who cannot tell you why the 'facts' they are teaching you are considered as facts and not just imagination (ie theory) is one of them. Another I found several times was longtime lecturers are so stuck in their ways they won't accept any other form of thought or ideas - totally the antithesis of what they are supposed to be about. Many of them are plain stark raving bonkers too but they have tunre and can't be fired for their incompetence, nor could they make it in the real worls - a place they have never visited. Give me the RNZAF education system anyday.
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Post by alanw on Aug 11, 2012 19:46:58 GMT 12
Hi Dave Unfortunately drilling to the outer core is far beyond our current technology. There have been attempts to at least get to the mantle over the last 50 years the most recent attempts at late as 2005, this link should provide some good reading for you www.livescience.com/6959-hole-drilled-bottom-earth-crust-breakthrough-mantle-looms.htmlThe issue with science in general it is theorectical at many stages, all Scientists can do is conduct experiments to support their theories, or obtain data which gives us an idea of what is happening. What I love about Earth Science is that there are times when you have physical evidence or have fun showing how things work. One of the coolest experiments I did, was to measure Isostasy in a Geophysics lab using "Treacle" to simuate the Mantle (Isostasy is the movement (mostly up/down) of the continents etc when weight (ie Ice Sheets) are added or taken away). Funny thing is we actually don't know how viscous the Mantle is, so Treacle may not be right! ;D Other times you get to actually see Earths Physical History in front of you. This Link shows a Cambrian (< 500 Million yrs) Granite Monolith in Mannum South Australia, that I have visited a number of times (that's not me by the way). You can see a Basaltic Dyke that has intruded at some point (going up the middle). What this photo doesn't show are the Xenoliths that have fallen into the Molten Granite as it intruded. (Xenoliths are pieces of surrounding or "Country" Rock). myweb.facstaff.wwu.edu/talbot/cdgeol/Igneous/Intrusive/59-051.jpgIf you read the article about the hole drilling, it mentions the "Moho" Discontinuity - a break in strata or Rock type. In the Mannum photo, you can clearly see the "Discontinuity" between the Granite, Sedimentary Rock (Mudstone from memory) and the the Kaylonite Sediment at the top. In this same place you can find fossils from when South Australia was covered by a shallow Sea I have found Trilobites and Ammonites, various types of Mollusca (shell fish) Earths history spanning 500 million years!! Another field trip was looking at road side cuttings and looking again at intrusions, and looking at minerals that had Slowly formed in the molten magma (Bowens Reaction Series) and seeing Mica Flakes(Muscovite type) as big as dinner plates (usually only specks in Granite etc) Muscovite has been used in toasters etc. Earth Science can be fun, I guess it didn't help for you to have a moron lecturer either Regards Alan
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Post by Dave Homewood on Aug 11, 2012 22:18:30 GMT 12
"The issue with science in general it is theorectical at many stages, all Scientists can do is conduct experiments to support their theories, or obtain data which gives us an idea of what is happening."
I agree with that. My main point is the particular scientist I was asking the question of, and I suspect many others out there too, could not distinguish the difference between an established theory and established fact, she assumed they were one in the same. Coming from more of an engineering and practical background, I simply cannot abide that discrepancy in her thinking.
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Post by mumbles on Aug 11, 2012 22:34:59 GMT 12
Nope. So my understanding at present is because no-one has been down there, nor has any probe or drill, it's all just a guess. Yes, but it's a very educated guess based on known facts. The scientific definition of 'theory' is very different and a lot more robust than the common one Beyond a certain depth there is no material that can withstand either the heat or pressure, so direct observation will be impossible.
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Post by ngatimozart on Aug 11, 2012 22:58:41 GMT 12
We use different tools to help us understand the world around us and the universe. Theories are just that theories; someones idea of what a particular thing is and they lay out their evidence to support their theory. You say that the wave theory used to determine the structure of the core and outer core of the earth may be superceded. That maybe so but at present it is a tool that we have to make observations. Another way of looking at it. What about an medical X-Ray? It shows some of the internal structures of your body. If we break a bone we get an x-Ray to see where the break is. But what are X-Rays. Long story short they are a form of energy at a particular wavelength within the electromagnetic spectrum. Just like light or radio waves etc. Now we know quite about about waves, their structures, how they propogate etc., and a significant amount of literature exists that explains and supports current wave theory. So I would suggest that the wave theory used to support the current theories on the structure of inner & outer core of the planet is quite robust.
In science all theories are basically predictions that have to be able to be disproved. Whether they are or not depends upon how good their predictions are. Both of Einsteins Theories of Relativity are subject to that criteria and that is how science validates knowledge and if you can prove Einstein wrong then that's an instant Nobel Prize. But remember science is just one way of attempting to explain the world around us. Part of its success is because it makes small theories, i.e., predictions, adding to its store of knowledge if those predictions are correct. If they are not correct the theory is discarded. At present it is the most effective one because of the succes rate of it's predictions.
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