On page 11, Shubin mentions 2 very interesting things. The first is how the summit of Mount Everest (nearly 5 miles above sea level) contains rocks from an ancient sea floor. The second is how fossils of Amazon-like plants have been found in rock layers north of the Arctic Circle. Explain how both of these phenomena occur and what they could tell us about the Earth’s past and future.
Matt Micucci (coochqbk@sbcglobal.net)
The simplest way that these two phenomena can be explained is that the Earth changes over time; as Shubin states, the "mountains rise and fall, climates warm and cool, and continents move about" (Shubin 11). Thus, environments that, in the past, were ancient sea floors or layers from the Arctic circle have changed over time to create the environments we see today.
ReplyDeleteA specific example of how the Earth changes over time is the tectonic plates that make up our planet; our planet, though once thought of as a solid, unbroken entity, is actually a "fluid mosaic of many irregular rigid segments, or plates" (http://www.platetectonics.com/book/page_2.asp). These plates move over time, causing natural disasters like earthquakes, but also gradually altering the environments that sit on the plates. Although this may seem insignificant since we can't physically see the plates moving ourselves, and since their movement is so gradual, we must remember that in regards to the millions and millions of years of evolutionary history before our time today, the movement of these plates has caused the changes that Shubin addresses in this passage. For example, "India and Asia crashed about 55 million years ago, slowly giving rise to the Himalaya, the highest mountain system on Earth" (http://science.nationalgeographic.com/science/earth/the-dynamic-earth/plate-tectonics-article/). Thus, we can see here that how our world today differs vastly from what it was millions of years ago, and this gradual change is what accounts for the differences in environment.
The phenomena of differences in environment tell us, mainly, that Earth is and always will be changing, and that it will change so unpredictably that we can't possibly depend on data from past years to tell us about the future. Therefore, it is important that we always keep an open mind for what can happen to our planet in the future, and how the environment can affect how we live and develop. In addition, how the environment changes can also give us insight on how we can affect the environment; an example is how we can attempt to preserve our world as it is today by recycling and conserving resources like water. All we know about the Earth's past can be seen by investigating the land and looking at the layers that Shubin talks about in his book; however, I don't believe that we can ever truly know what the Earth looked like so long ago, because it changes so constantly that all we can do is speculate based on what we have. In the future, millions of years from now, our Earth will most likely look completely different from how it does today.
Sources:
Your Inner Fish
http://www.platetectonics.com/book/page_2.asp
http://science.nationalgeographic.com/science/earth/the-dynamic-earth/plate-tectonics-article/
Kathy Li, kathy2132@gmail.com
Kathy is absolutely correct about the fact that the Earth is constantly changing, which has caused both of the phenomena. The fact that "mountains rise and fall, climates warm and cool, and continents move about" tells us that the future is quite uncertain for our Earth; our sea floors today could be mountain tops someday (Shubin 11).
ReplyDeleteTo specifically discuss these individual phenomena, over millions of years, rivers washed rocks and soil from existing mountains onto the Indian subcontinent and nearby Asia into a shallow sea where the sediment was deposited on the floor. Layer upon layer of sediment built up over millions of years until the pressure and weight of the overlying sediment caused the stuff way down deep to turn into rock. Then about 40 million years ago, in a process called "uplifting", the sea floor began to be forced upward forming mountains (http://www.visit-himalaya.com/himalayas/mount-everest.html).
Along with fossils of tropical plants found in the Arctic circle, a fossil of a tropical turtle has been discovered as well. This turtle is said to have migrated 90 million years ago when temperatures on Earth were peaking. The combination of volcanism in the Arctic Circle along with high temperatures caused from increasing levels of carbon dioxide provided a suitable environment for many reptiles. In fact, "the waters around the North Pole were warm enough for a comfortable swim 55 million years ago, and year-round average land temperatures in the tropics may have reached 105 degrees Fahrenheit" (http://www.wired.com/wiredscience/2009/02/tropical-turtle/).
Both of these occurrences were because of Earth's ability and propensity to change over time, along with chemical evolution that took place on a younger Earth. Like Kathy pointed out, we can never truly know what Earth looked like 90 million years ago, and we will have no idea what our Earth will look like 90 million years in the future.
http://www.wired.com/wiredscience/2009/02/tropical-turtle/
http://www.visit-himalaya.com/himalayas/mount-everest.html
Hannah Kay (hgkay@aol.com)
Hannah brings up a great point that uplifting occurred along the sea floor causing the continents to collide and create mountains. However, it doesn’t explain why certain Amazonian fossils were found in the artic. As many scientists strongly believe, a supercontinent, Pangaea, was present 250 million years ago. The earth was connected then. With certain organisms that are the same in many areas, the supercontinent began rifting. Both active rifting and passive rifting occurred. It is speculated that the passive rifting occurred during the early Jurassic period and the active rifting occurred during the Cretaceous supercontinental period. These two types of rifts that occurred explain why certain continents are where they are at the moment. This tells us why some organisms are very similar to other organisms even though they are located halfway across the world. This can tell us nothing of the future of earth. Only scientists can see what will happen in the future. As seen in the movie 2012, although not the most reliable resource, it makes a good point. Scientists contain technology that can potentially see changes in the movement of our continents. They have the technology or are close to making technology that can see the temperature of our earth’s core. With this technology, we can see the future of our planet. However, nothing can be said of the future at this day and age.
ReplyDeleteSources:
http://adsabs.harvard.edu/abs/1990Geo....18..323H
http://library.thinkquest.org/17701/high/pangaea/
Shreeraj Patel
shreeraj.patel1@gmail.com
The term Shreeraj was describing above was plate tectonics. This is the movement of the earths crust moves into one another causing friction. "Plates only move a few centimeters each year, so collisions are very slow and last millions of years." http://www.cotf.edu/ete/modules/msese/earthsysflr/plates2.html The ocean plates collide with one another and it causes such intense pressures that one plate goes underground and the other rises above sea level. That is why you see very high mountains (Everest) and others that are deep trenches (like one found beside Japan). http://illinois.edu/lb/article/72/49232 Using this information, you can tell that fossils can be moved over a very different rock layers. And at the same time, these ocean plates also move away from each other. Therefore, fossils can be displaced thousands of miles from the original spot at where the organism died.
ReplyDeleteThe way that geologists use this information for their advantage is by noticing patters found in the earths crust. As Shreeraj stated above, there was a 'Pangaea' way back 250 million years ago, where all the continents were combined into one giant land mass. They are tracking the global patterns of how certain plates are moving now. They look at transform boundaries, places where plates slide past each other, to see/ predict possible earthquakes and volcanic eruptions. A good example of this is California. "The slice of California to the west of the fault is slowly moving north relative to the rest of California." http://www.cotf.edu/ete/modules/msese/earthsysflr/plates4.html
Nikhil Pereira (nikhil.pereira3@gmail.com)