Additional Notes - Where Giants Roam
Original Article - Where Giants Roam.
The subject of plate tectonics was one that I was eager to start reading about, and I found it hard to stop researching and start writing about. As I’ve mentioned in the article, I learned about this subject in high school, and also a bit in college. Still, I was under evaluating how interesting it could be. I got the kickstart I needed once I heard that we don’t know of other planets that have plate tectonics. This fact has immediately turned the subject into an urgent question in my mind.
I’ll take this chance to say that while we don’t know of any other planets that currently have plate tectonics, some planets have shown signs of having tectonic activity in the past. And also, here are a couple of articles about what might prove to be tectonic activity on mars and on Europa, Jupiter’s moon.
This might have been the topic I’ve done the most research about so far. As always, I have a few extra tidbits, if you are still interested.
So, we now accept that the plates are moving. I mentioned in the article that the movement is slow. Well, it is hard to grasp how slow it really is. Some plates are faster than others, but even the fast ones are not impressively quick. The average speed is about 2-5 centimeters a year. That is comparable to a normal person’s nail growth rate. You know how sometimes people prank their friends by moving all the furniture in their friends’ living room by a few centimeters? Usually, these few centimeters of movement go unnoticed. And they don’t happen over a year. What I’m saying is, there’s no way that you’ll wake up one day and be surprised at how far the plates have gone since you last looked.
The movement of the plates may be slow, but it’s been happening for a long time now. On a geological timescale, the movement is definitely noticeable, and we can try to estimate where will the continents in the future. Spoiler alert: Don’t base your plans for the future on the fact that your house is going to be in the same place for the next few millions of years. According to estimations of the Plaeomap Project, Europe and Africa will collide, closing the gap that is the mediterranean sea, and creating a long mountain range in about 50 million years. It is believed that new subduction zones will appear at the coasts of North and South America, leading to the formation of new mountain chains along these coasts. At about 100 million years from now, the continents will begin to move towards each other again. Thus, in 250 million years, North America will collide with Africa, South america will wrap itself around the mass of land that will form, and a new supercontinent, Pangea Ultima, will be formed. There’s a great clip on youtube, that shows how the surface of the Earth looked in the past and will look in the future.
Here’s some cool information about mountains. I mentioned that most mountains on Earth are being raised due to interactions between plates. If you measure mountains from base to peak, instead of the usual water surface to peak, the tallest mountain on earth is Mauna Kae, in Hawaii, at 10,203 meters (33,476 feet). This may seem impressive, but compare it to the tallest mountain on a planet in the solar system and suddenly it seems like a dwarf. The tallest mountain is located on the western hemisphere of Mars, and its name is Olympus Mons. I thought that name was taken, but I guess if it’s on another planet... Anyway, the martian Olympus reaches a towering 21,287 meters, or 69,841 feet.
Most mountains on mars are formed by a different mechanism than those on Earth. The major factors for mountain formations on earth are plate tectonics and liquid water erosion, which Mars does not have. The major factor for mountain formation on Mars is wind erosion, that is why most mountains on Mars appear inside craters - the wind blows away any light materials and the heavier ones stay put. But Olympus Mons is a shield volcano, which is a different type altogether.
We have shield volcanoes here on Earth - Mauna Kae and the hawaiian islands are a chain of shield volcanoes. You see, the volcanoes in Hawaii are not near plate boundaries, like you might expect, but they are very near a hotspot. The Hawaii hotspot, to be exact. A hotspot is an area in the mantle that is irregularly hot, so it experiences relatively frequent volcanic eruptions, even if it is far away from a plate boundary. What makes these volcanoes a shield type volcanoes is the fact that they usually erupt in a very fluid form. That means that lava flows and does not dramatically explode. It then cools down and harden. After many eruptions, the hardened lava accumulates and forms a wide, usually short, mountain - kind of in a shape of a shield.
The difference between Olympus Mons and the Hawaiian volcano chain is, again, plate tectonics. The Pacific plate moves over the Hawaii hotspot, which erupts occasionally, and creates a chain of volcanoes. Olympus Mons is not on a moving plate, and so the eruptions always take place on the same relative location. Eruption after eruption accumulates more hardened lava, which add to the impressive height of the tallest mountain on a planet in our solar system. On earth, the weather would have carved through the mountain, given enough time.
As usual, there is still much more to say about this subject - much more than I could fit in an article and an additional notes post.
I hope you found this interesting!