Geologic Mapping C

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Re: Geologic Mapping C

Post by syo_astro » February 23rd, 2015, 6:07 pm

boomvroomshroom wrote:In general the event is just so painful to study for because they literally can just ask you anything, and most people don't know much about it anyway (even if they're geology majors or whatever because no one is really sure what to ask).

Last year the Nationals test was pretty reasonable, but I remember our regionals test was pretty crazy. The entire thing was made up of calculation-based word problems, and about a quarter of them were just borderline geology-based. The math itself wasn't hard, but it took a lot of reasoning skills (we had never seen those types of problems before and so we had to draw out and derive the formulas ourselves).

Don't get me wrong, Geomaps is a great event, but it's just so unpredictable.
Yes and no. I've done the event for 3 years in NYS, where it originated. I think us original folk that have done it can say we've had it tough ;). Trust me, I know what you mean, but NYS Geomaps is uh...definitely made by someone who knows his stuff. My complaint has always been how broad the event has been, but it seems like nothing has changed much, if anything it's only gotten broader. At least it makes you appreciate geology! I say no only because by the third year...I kinda got the gist of what was gonna be asked (at least leagues ahead of when I first did it).
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Re: Geologic Mapping C

Post by Metasepia_pfefferi » March 2nd, 2015, 5:34 pm

Can someone please verify which is the correct formula to use when finding true thickness? The formula my partner and I used is AB= WsinD + HcosD which we got from https://www.uwgb.edu/dutchs/structge/SL47TrueThk.HTM. however, at an invitationals, the formula the proctors used for the problem was AB = WsinD + HsinD.
Thanks in advance!

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Re: Geologic Mapping C

Post by boomvroomshroom » March 2nd, 2015, 9:01 pm

Metasepia_pfefferi wrote:Can someone please verify which is the correct formula to use when finding true thickness? The formula my partner and I used is AB= WsinD + HcosD which we got from https://www.uwgb.edu/dutchs/structge/SL47TrueThk.HTM. however, at an invitationals, the formula the proctors used for the problem was AB = WsinD + HsinD.
Thanks in advance!
It should be WsinD+HcosD. If you've taken geometry, sinD=AC/W and cosD=CB/H, thus WsinD=AC and HcosD=CB; AC+CB=AB=WsinD+HcosD.
The graders either got that one wrong, or perhaps used a different angle? (Perhaps you thought they were using D, but in reality they were using the complement of D on the other side...)

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Re: Geologic Mapping C

Post by hipparcos » March 5th, 2015, 5:11 am

boomvroomshroom wrote:
Metasepia_pfefferi wrote:Can someone please verify which is the correct formula to use when finding true thickness? The formula my partner and I used is AB= WsinD + HcosD which we got from https://www.uwgb.edu/dutchs/structge/SL47TrueThk.HTM. however, at an invitationals, the formula the proctors used for the problem was AB = WsinD + HsinD.
Thanks in advance!
It should be WsinD+HcosD. If you've taken geometry, sinD=AC/W and cosD=CB/H, thus WsinD=AC and HcosD=CB; AC+CB=AB=WsinD+HcosD.
The graders either got that one wrong, or perhaps used a different angle? (Perhaps you thought they were using D, but in reality they were using the complement of D on the other side...)
Apparently you also have to take into account whether the ground and bed are sloping down in the same direction or in opposite directions... I think in the latter case, above formula works, but in the former case, you take the difference of WsinD and HcosD, not the sum.
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Re: Geologic Mapping C

Post by boomvroomshroom » March 5th, 2015, 4:24 pm

hipparcos wrote:
boomvroomshroom wrote:
Metasepia_pfefferi wrote:Can someone please verify which is the correct formula to use when finding true thickness? The formula my partner and I used is AB= WsinD + HcosD which we got from https://www.uwgb.edu/dutchs/structge/SL47TrueThk.HTM. however, at an invitationals, the formula the proctors used for the problem was AB = WsinD + HsinD.
Thanks in advance!
It should be WsinD+HcosD. If you've taken geometry, sinD=AC/W and cosD=CB/H, thus WsinD=AC and HcosD=CB; AC+CB=AB=WsinD+HcosD.
The graders either got that one wrong, or perhaps used a different angle? (Perhaps you thought they were using D, but in reality they were using the complement of D on the other side...)
Apparently you also have to take into account whether the ground and bed are sloping down in the same direction or in opposite directions... I think in the latter case, above formula works, but in the former case, you take the difference of WsinD and HcosD, not the sum.
In general you shouldn't be using formulas; just draw a picture and use geometry.

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Re: Geologic Mapping C

Post by elephantower » March 10th, 2015, 8:46 pm

boomvroomshroom wrote:
hipparcos wrote:
boomvroomshroom wrote: It should be WsinD+HcosD. If you've taken geometry, sinD=AC/W and cosD=CB/H, thus WsinD=AC and HcosD=CB; AC+CB=AB=WsinD+HcosD.
The graders either got that one wrong, or perhaps used a different angle? (Perhaps you thought they were using D, but in reality they were using the complement of D on the other side...)
Apparently you also have to take into account whether the ground and bed are sloping down in the same direction or in opposite directions... I think in the latter case, above formula works, but in the former case, you take the difference of WsinD and HcosD, not the sum.
In general you shouldn't be using formulas; just draw a picture and use geometry.
Yup, pretty much. If you want that done for you, though (or want to save time), take a gander at this picture
Image
Last edited by elephantower on March 10th, 2015, 8:50 pm, edited 1 time in total.
[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, ?

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Re: Geologic Mapping C

Post by elephantower » March 10th, 2015, 8:50 pm

kmbrgandhi3 wrote:Hey: at the invitationals I attended this year, we generally did well on 'informational' questions and could solve the majority of the stereonet/mathematics-based problems. However, there were always a couple more mathematically focused questions that tripped us up – looking back at the problems, I have been able to figure out how to do all of them with sufficient time, but I'm wondering if there is a good bank for problems that is decently comprehensive. I don't want to get tripped up similarly at states, and I think that having been exposed to more problems would help my time efficiency.

I know that this question is probably impossible to answer completely, since I imagine that there isn't one particular website or book with all of the problems that we need to know – but if people could direct me to good sets of problems that generally cover the topics in question, it would be much appreciated.
Not to toot my own horn, but have you solved all my practice test problems on the test exchange? They're very mathematical, and give a general overview of the skills required in this event.
[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, ?

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Re: Geologic Mapping C

Post by boomvroomshroom » March 11th, 2015, 8:56 pm

elephantower wrote:
kmbrgandhi3 wrote:Hey: at the invitationals I attended this year, we generally did well on 'informational' questions and could solve the majority of the stereonet/mathematics-based problems. However, there were always a couple more mathematically focused questions that tripped us up – looking back at the problems, I have been able to figure out how to do all of them with sufficient time, but I'm wondering if there is a good bank for problems that is decently comprehensive. I don't want to get tripped up similarly at states, and I think that having been exposed to more problems would help my time efficiency.

I know that this question is probably impossible to answer completely, since I imagine that there isn't one particular website or book with all of the problems that we need to know – but if people could direct me to good sets of problems that generally cover the topics in question, it would be much appreciated.
Not to toot my own horn, but have you solved all my practice test problems on the test exchange? They're very mathematical, and give a general overview of the skills required in this event.
Do you remember what those problems were? Generally when there's "weird" math problems (that diverge from stereonets and basic stuff), they have no specific "solution format". But we can probably figure it out if we stare at it for long enough.

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Re: Geologic Mapping C

Post by elephantower » March 12th, 2015, 4:15 pm

boomvroomshroom wrote:
elephantower wrote:
kmbrgandhi3 wrote:Hey: at the invitationals I attended this year, we generally did well on 'informational' questions and could solve the majority of the stereonet/mathematics-based problems. However, there were always a couple more mathematically focused questions that tripped us up – looking back at the problems, I have been able to figure out how to do all of them with sufficient time, but I'm wondering if there is a good bank for problems that is decently comprehensive. I don't want to get tripped up similarly at states, and I think that having been exposed to more problems would help my time efficiency.

I know that this question is probably impossible to answer completely, since I imagine that there isn't one particular website or book with all of the problems that we need to know – but if people could direct me to good sets of problems that generally cover the topics in question, it would be much appreciated.
Not to toot my own horn, but have you solved all my practice test problems on the test exchange? They're very mathematical, and give a general overview of the skills required in this event.
Do you remember what those problems were? Generally when there's "weird" math problems (that diverge from stereonets and basic stuff), they have no specific "solution format". But we can probably figure it out if we stare at it for long enough.
Pretty much, as long as you know all the basic trig formulae relating apparent dip to true dip to angle of obliquity, etc.
[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, ?

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Re: Geologic Mapping C

Post by boomvroomshroom » March 16th, 2015, 9:21 am

Quick question: what's the most complicated problem you've ever seen, ever? Mine was actually at a regionals, where we had to calculate original apparent dip with like three faults in the way. State and Nats didn't even come close XD

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