Mountains and tectonic plates

Does your world need to be the same as the "real" one and therefore refer to past plate margins, or is it a fantasy world? If it's the later you can pretty much do what you want! If it's the former, there's plenty of information out there.

Even though I slept through much of it, I've got a degree in geology and remember doing this sort of stuff at the start of my first year. There's past and present projections based on current tectonic movements, some of which can now be viewed as animations on youtube.

"The present is the key to the past", according to many of my lecturers.

I'll have a cyber root round and get back to you. FYI, us Limeys have different names for some of the geological periods, so bear this in mind if I find a UK-produced resource.

https://www.youtube.com/watch?v=Cm5giPd5Uro
https://www.youtube.com/watch?v=uGcDed4xVD4

Plenty of other youtube clips if you look to the right of the screen.

http://www.earthhistory.org.uk/key-concepts/plate-tectonics-1

http://www.ucmp.berkeley.edu/geology/tectonics.html

http://www.geolsoc.org.uk/Plate-Tectonics/Chap4-Plate-Tectonics-of-the-UK

http://www.livescience.com/31910-north-america-geology-through-time.html

https://www.uwgb.edu/dutchs/EarthSC102Notes/102PTEarthHist.htm

http://www.bbc.co.uk/science/earth/surface_and_interior/plate_tectonics

[url]http://www.darkroastedblend.com/2010/03/future-plate-tectonics.html

https://www.classzone.com/books/ear...807/es0807page01.cfm?chapter_no=visualization

https://www.youtube.com/watch?v=tv6p48v0meE


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Mountains can be produced by volcanic activity downstream of a subduction boundary, by volcanic activity caused by a hotspot, which need not bear any relation to plate boundaries, by crustal folding caused by plate collisions, and probably by other processes that I can't think of right now. And if you're in a fantasy world, are they going to be discussing this?

Draconess25 said:

It's very important for my world to feel real and like it just fits together. Obviously newer mountains will be placed along convergent plate boundaries, but what about older mountains formed millions of years ago by plates that have long since moved? Are plate movements unpredictable enough that I can just throw the older mountain ranges wherever I want, or should I try to somehow rewind my plates by millions of years?

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In some cases the plates that moved together to make a mountain range may have become solid parts of a continental plate, so there would be no active faults in the area. Unless the geology is very important to the story, I don't think you should go into details about how any mountains were formed. Then again the faults can become active again aeons after the mountains eroded to flatland, as is true in your area. The New Madrid faults are where pieces of earlier plates came together to become parts of the North American plate.

I regard the subject very, very interesting,but I live in an area that has has some varied tectonic activity, and I live in a place that is a stone's throw from where faults opened into oceans twice. I don't think thtat geology makes good stories, because geology is too slow.

Older mountain ranges exist in many areas that are away from current plate boundaries. Some of these may be between minor plates that have fused together or in an area where there used to be volcanic activity. I live in Bohemia, an area of very old, extinct volcanoes. Be aware that in such areas the mountains are not high and jagged. They are low and rounded, with the occasional peak. Also these are the areas where you most often find mines for coal, iron, natural gas and other deposits that take a long time to accumulate. New mountains that are tall and jagged, tend not to have as much of this, which is why you have more coal in lower mountains like the Appalachians than in the Rockies. There are more hot springs in newer mountains but a few very mineral-heavy hot springs can be found in the ancient mountains of Bohemia as well. Caves tend to be found in mountains made of materials like limestone. These are best formed by an ancient seabed being lifted in a plate collision. I'm not sure about volcanic mountains and caves. I'm not recalling any major caves in volcanic rock. Something to think about. You are unlikely to have a cave with obsidian walls unless it was magic.

Draconess25 said:

It's very important for my world to feel real and like it just fits together. Obviously newer mountains will be placed along convergent plate boundaries, but what about older mountains formed millions of years ago by plates that have long since moved?

Click to expand...

The Hercynian Orogeny, which took place hundreds of millions of years ago, is recorded today in the stretch of mountains from the Appalachians northeastward through the Scottish Highlands and on into Norway. Obviously, that range, which would have been as high as, and longer than, the Himalayas, has been sundered by the opening of the North Atlantic Ocean, and heavily eroded. Even older, and more heavily eroded, is the Peterman Range in Australia.

And there are big mountain ranges not associated with plate boundaries, the most obvious of which is the Rockies.

You're in charge of your world's geography. Make it how you need it to be for the story.

caw

And there are also mountains like the Catskills that are not, geologically speaking, mountains at all, but eroded plateaus. Eventually they erode into mesas & buttes, and ultimately wear away altogether.

Scottish mountains are very old and their tops are rounded due to glacial erosion. Or so I've been told.

And, from something I vaguely remember from one of my lectures, England and Scotland used to be on different tectonic plates. Rocks in Scotland are some of the oldest in the UK, and some contain magnetic minerals which play havoc with a compass.

I also recall us being told that around the time the Atlantic was opening up there was also a rift forming along what's now the North Sea. For a geological while it was undecided which one would open properly, but the Atlantic one "won" - hence the UK is much nearer Norway than Canada.

Can't remember the details of anything I've just said above, but at least I was awake in a lecture instead of snoozing/hungover/reading a magazine/perving over the solitary piece of eye candy on my course.

Los Pollos Hermanos said:

And, from something I vaguely remember from one of my lectures, England and Scotland used to be on different tectonic plates. Rocks in Scotland are some of the oldest in the UK, and some contain magnetic minerals which play havoc with a compass.

I also recall us being told that around the time the Atlantic was opening up there was also a rift forming along what's now the North Sea. For a geological while it was undecided which one would open properly, but the Atlantic one "won" - hence the UK is much nearer Norway than Canada.

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Great Britain has a very complicated collection of pieces of different plates. I couldn't find a map of them immediately, but the map on the page from British geology on Wikipedia is fairly good.
https://en.wikipedia.org/wiki/Geology_of_Great_Britain

afarnam said:

Caves tend to be found in mountains made of materials like limestone. These are best formed by an ancient seabed being lifted in a plate collision. I'm not sure about volcanic mountains and caves. I'm not recalling any major caves in volcanic rock. Something to think about. You are unlikely to have a cave with obsidian walls unless it was magic.

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In volcanic regions you can have lava caves/lava tubes.

I remember this bad boy from back in the day (I assume I had a later edition):

http://www.amazon.co.uk/dp/0045510288/?tag=absowrit-21

I also had to spend a month in the North Wales town which inspired Deliverance making one of those geological maps of the area. Got munched by ticks, chased by the local nutter (well, the maddest one of many) and wished I'd gone to Spain* with my course buddies.

* They were studying metamorphic rocks; I prefer igneous (Shap granite is my all-time favourite rock, but nobody from my course went mapping in the Lake District) and a spot of sedimentary.

Draconess25 said:

It's very important for my world to feel real and like it just fits together. Obviously newer mountains will be placed along convergent plate boundaries, but what about older mountains formed millions of years ago by plates that have long since moved? Are plate movements unpredictable enough that I can just throw the older mountain ranges wherever I want, or should I try to somehow rewind my plates by millions of years?

Click to expand...

This is also I've been really interested in during my world-building.

I'm an ecologist, not a geologist, so what I've been paying more attention to is how mountains/geology influences the plant/animal life and climate. However in my experience plate tectonics can be very active (on a geologic time scale). Older plates can be completed melted away and new plates formed (look up the Farallon Plate). Plates could break away from the main plate. The Rockies were formed by tectonic plate activity from a variety of sources. The southern range may have been formed by subduction of the Farallon plate below the North American Plate. The Canadian Rockies are pushed up by a combination of broken-off continental plates pushing up against them (like wrinkling a rug) and subduction. Of course, this is a simplified explanation.

The Sierra Nevada in California is formed by subduction of the Pacific Plate below the North American Plate and then pressure from the Pacific Plate combined with a fault line along the east is tilting the range to the west and it is still rising. The Cascade and Klamath Ranges to the north of the Sierras are volcanic. The Sierra also used to be volcanic before the granite was uplifted but most of the volcanic rock has eroded away.

I think you could place mountains where you want and could easily come up with a reason for them to be there because there are so many ways mountains can form. In my world I have ranges caused by subduction of an oceanic plate beneath a continental plate, volcanic activity, two continental plates running into each other, and another caused by a huge magical explosion during the time of the war of the "gods".