GeoLogic Mapping C

User avatar
Magikarpmaster629
Exalted Member
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
Division: Grad
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

Re: GeoLogic Mapping C

Postby Magikarpmaster629 » March 12th, 2015, 10:19 am

How are mid-ocean ridges formed?
Ladue Science Olympiad (2014ish-2017)

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

User avatar
boomvroomshroom
Member
Member
Posts: 189
Joined: February 19th, 2015, 5:10 pm
Division: C
State: CA

Re: GeoLogic Mapping C

Postby boomvroomshroom » March 12th, 2015, 3:54 pm

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).

User avatar
elephantower
Member
Member
Posts: 97
Joined: November 23rd, 2013, 6:36 pm
Division: C
State: AZ

Re: GeoLogic Mapping C

Postby elephantower » March 12th, 2015, 4:14 pm

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).
[S/N]
N/A = didn't compete

2013:
Geologic Mapping: 1, 2
Designer Genes: 3, :(
Astronomy: N/A, :(
2014:
Geologic Mapping: 1, N/A
Protein Modelling: 1, N/A
It's About Time: 1, N/A
Forensics: 9, N/A
2015:
Geologic Mapping: 1, ?
Hydrogeology: 1, ?
It's About Time: 1, ?
Forensics: 10, ?

User avatar
boomvroomshroom
Member
Member
Posts: 189
Joined: February 19th, 2015, 5:10 pm
Division: C
State: CA

Re: GeoLogic Mapping C

Postby boomvroomshroom » March 13th, 2015, 9:45 am

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 :)

User avatar
Magikarpmaster629
Exalted Member
Exalted Member
Posts: 578
Joined: October 7th, 2014, 3:03 pm
Division: Grad
State: MA
Location: No idea, but I can tell you exactly how fast I'm going

Re: GeoLogic Mapping C

Postby Magikarpmaster629 » March 13th, 2015, 11:29 am

Yes, Elephantower is correct. Either of you may ask a question now!
Ladue Science Olympiad (2014ish-2017)

A wild goose flies over a pond, leaving behind a voice in the wind.
A man passes through this world, leaving behind a name.

User avatar
elephantower
Member
Member
Posts: 97
Joined: November 23rd, 2013, 6:36 pm
Division: C
State: AZ

Re: GeoLogic Mapping C

Postby elephantower » March 13th, 2015, 9:00 pm

Yay.

Question/Problem:
Derive the analytical 3 point problem formula
true dip = arctan(tan(A1)/sin(90 - arctan(csc(θ)*(cot(A1)*tan(A2)-cos(θ)))))

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.
[S/N]
N/A = didn't compete

2013:
Geologic Mapping: 1, 2
Designer Genes: 3, :(
Astronomy: N/A, :(
2014:
Geologic Mapping: 1, N/A
Protein Modelling: 1, N/A
It's About Time: 1, N/A
Forensics: 9, N/A
2015:
Geologic Mapping: 1, ?
Hydrogeology: 1, ?
It's About Time: 1, ?
Forensics: 10, ?

User avatar
boomvroomshroom
Member
Member
Posts: 189
Joined: February 19th, 2015, 5:10 pm
Division: C
State: CA

Re: GeoLogic Mapping C

Postby boomvroomshroom » March 14th, 2015, 10:14 am

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...

User avatar
elephantower
Member
Member
Posts: 97
Joined: November 23rd, 2013, 6:36 pm
Division: C
State: AZ

Re: GeoLogic Mapping C

Postby elephantower » March 15th, 2015, 2:17 pm

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.
[S/N]
N/A = didn't compete

2013:
Geologic Mapping: 1, 2
Designer Genes: 3, :(
Astronomy: N/A, :(
2014:
Geologic Mapping: 1, N/A
Protein Modelling: 1, N/A
It's About Time: 1, N/A
Forensics: 9, N/A
2015:
Geologic Mapping: 1, ?
Hydrogeology: 1, ?
It's About Time: 1, ?
Forensics: 10, ?

User avatar
boomvroomshroom
Member
Member
Posts: 189
Joined: February 19th, 2015, 5:10 pm
Division: C
State: CA

Re: GeoLogic Mapping C

Postby boomvroomshroom » March 15th, 2015, 6:43 pm

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.

User avatar
elephantower
Member
Member
Posts: 97
Joined: November 23rd, 2013, 6:36 pm
Division: C
State: AZ

Re: GeoLogic Mapping C

Postby elephantower » March 15th, 2015, 10:22 pm

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 :P
[S/N]
N/A = didn't compete

2013:
Geologic Mapping: 1, 2
Designer Genes: 3, :(
Astronomy: N/A, :(
2014:
Geologic Mapping: 1, N/A
Protein Modelling: 1, N/A
It's About Time: 1, N/A
Forensics: 9, N/A
2015:
Geologic Mapping: 1, ?
Hydrogeology: 1, ?
It's About Time: 1, ?
Forensics: 10, ?


Return to “2015 Question Marathons”

Who is online

Users browsing this forum: No registered users and 1 guest