Just like most major mountain ranges, it's when two plates converge and push each other up (although in this case, they're converging underneath the ocean instead of on land).
Re: GeoLogic Mapping C
Posted: March 12th, 2015, 4:14 pm
by elephantower
Reverse underwater faulting produces trenches; mid-ocean ridges are formed by normal faulting (specifically from magma welling up from the rift created).
It's the difference between pushing two bread loaves together (continental plates are thick but not dense, ) and pushing two greasy pancakes together (ocean crust is thin and compact).
Re: GeoLogic Mapping C
Posted: March 13th, 2015, 9:45 am
by boomvroomshroom
elephantower wrote:
Reverse underwater faulting produces trenches; mid-ocean ridges are formed by normal faulting (specifically from magma welling up from the rift created).
It's the difference between pushing two bread loaves together (continental plates are thick but not dense, ) and pushing two greasy pancakes together (ocean crust is thin and compact).
looked it up, and you're right. Got confused; sorry! Thanks for the info
Re: GeoLogic Mapping C
Posted: March 13th, 2015, 11:29 am
by Magikarpmaster629
Yes, Elephantower is correct. Either of you may ask a question now!
Re: GeoLogic Mapping C
Posted: March 13th, 2015, 9:00 pm
by elephantower
Yay.
Question/Problem:
Derive the analytical 3 point problem formula
Where A1 and A2 are the two apparent dips (A1 < A2) and θ is the angle between the A1 and A2 trendlines.
It looks stupidly complicated but it's actually extremely useful: much easier and more precise than constructing the solution. Also, I may have made a typo in it, please correct me if so.
Bonus points if you can simplify the final result.
Re: GeoLogic Mapping C
Posted: March 14th, 2015, 10:14 am
by boomvroomshroom
What do you mean by derive? I just drew a picture and labeled the sides, and did some trig.
Seems useful, but all the tests I've seen force you to show your work by drawing the picture thing, so...
Re: GeoLogic Mapping C
Posted: March 15th, 2015, 2:17 pm
by elephantower
boomvroomshroom wrote:What do you mean by derive? I just drew a picture and labeled the sides, and did some trig.
Seems useful, but all the tests I've seen force you to show your work by drawing the picture thing, so...
Derive the equation from basic trig identities? Scan up/transcribe your work perhaps? I'm curious to see how you did it. I've never seen a test like that, but it's still useful to check your work, as it's easy to introduce error when constructing the answer.
Re: GeoLogic Mapping C
Posted: March 15th, 2015, 6:43 pm
by boomvroomshroom
elephantower wrote:
boomvroomshroom wrote:What do you mean by derive? I just drew a picture and labeled the sides, and did some trig.
Seems useful, but all the tests I've seen force you to show your work by drawing the picture thing, so...
Derive the equation from basic trig identities? Scan up/transcribe your work perhaps? I'm curious to see how you did it. I've never seen a test like that, but it's still useful to check your work, as it's easy to introduce error when constructing the answer.
*kind of lazy* but I just drew the regular 3-point problem diagram, sketched it out in 3D, labeled the sides, and did some algebra. I did it before (also had to derive the true dip/apparent dip thing this way) on some practice test. I just can't find it right now, so I don't know what I did exactly, haha. I might send it back to you when I have some time. For something as 'complicated' as a 3-point problem (I say 'complicated' as in compared to true thickness) I'd just memorize your equation. I've never seen a question that asked you to derive something.
Anyway, the tests I had said in the instructions "show your work on the graph below" and they gave you this thing to plot the 3 points on and whatnot.
Re: GeoLogic Mapping C
Posted: March 15th, 2015, 10:22 pm
by elephantower
boomvroomshroom wrote:
elephantower wrote:
boomvroomshroom wrote:What do you mean by derive? I just drew a picture and labeled the sides, and did some trig.
Seems useful, but all the tests I've seen force you to show your work by drawing the picture thing, so...
Derive the equation from basic trig identities? Scan up/transcribe your work perhaps? I'm curious to see how you did it. I've never seen a test like that, but it's still useful to check your work, as it's easy to introduce error when constructing the answer.
*kind of lazy* but I just drew the regular 3-point problem diagram, sketched it out in 3D, labeled the sides, and did some algebra. I did it before (also had to derive the true dip/apparent dip thing this way) on some practice test. I just can't find it right now, so I don't know what I did exactly, haha. I might send it back to you when I have some time. For something as 'complicated' as a 3-point problem (I say 'complicated' as in compared to true thickness) I'd just memorize your equation. I've never seen a question that asked you to derive something.
Anyway, the tests I had said in the instructions "show your work on the graph below" and they gave you this thing to plot the 3 points on and whatnot.
Sounds good. Ask a question? Or I can give you a make-up question since that one was sorta silly
