GeoLogic Mapping C

[TwelveSquared]

Hello!
Welcome to the question marathon for GeoLogic Mapping! Enjoy your stay.

the seed question:

What geological structure is featured in this photo?

[elephantower]

or are you being boring and looking for "synform" (Click to Show Hidden Text)

chevron fold, or to be precise (bottom to top) chevron fold, unconformity, synform

[TwelveSquared]

'Tis right!

[elephantower]

I'm walking out in the desert when I notice a seam of gold ore outcropping right under my feet, at an elevation of 750 m. I then walk 80 m NW and come to another outcropping of the same seam (at an elevation of 1000 m). Eager to stake a claim to the bed, I run SSE to get back to my car, nearly missing a third outcrop 200 m away from the 2nd, at an elevation of 600 m. Assuming the ore forms a planar bed, what is the strike and dip of the bed? Explain your method for solving the problem.

[elephantower]

Welp did I kill the question marathon? Should I give a hint/easier question?

[HeavyHitter406]

Elephant, remember a lot of us are just starting this event...I know I am just getting into this stuff. Maybe we should start off a bit easier, like something we could get with only a couple days of studying:D

[zerasaw]

elephantower I haven't started studying yet but wouldn't it just be the cross product of the 2 vectors?

[Trackest]

I'm walking out in the desert when I notice a seam of gold ore outcropping right under my feet, at an elevation of 750 m. I then walk 80 m NW and come to another outcropping of the same seam (at an elevation of 1000 m). Eager to stake a claim to the bed, I run SSE to get back to my car, nearly missing a third outcrop 200 m away from the 2nd, at an elevation of 600 m. Assuming the ore forms a planar bed, what is the strike and dip of the bed? Explain your method for solving the problem.

Strike is 0 degrees and dip is 76.5 degrees? I marked the contours then calculated the dip angle by measuring the distance between each contour line and using trig with the depth difference. The strike was just the azimuth of the contours I think.

[elephantower]

Heavyhitter, your not living up to your name
um idk what crossproducts are but it certainly does involve vectors (the way I did it).

I got dip of (Click to Show Hidden Text)

75.6 degrees -- did you switch digits? :/

and

strike of (Click to Show Hidden Text)

98.5 degrees

. I'm sure that the strike isn't 0 from inspection; how exactly did you get that?

I did this quickly, and rounded carelessly, so my numbers could be off.

EDIT: Read about crossproducts: if I understand them that would give the strike; how would you get the dip?

[elephantower]

Also, that question was aimed at 2nd year geomappers, so maybe I should do a separate one for the young 'uns .
Here's one that's somewhat difficult, but requires little prior knowledge and should develop necessary spatial analysis skills.


The image above shows an outcrop of quartzite in sedimentary rock, plotted onto a topographic map by an intrepid observer. Does the quartzite form a fold? How can you tell from the map? If it forms a fold, is it an antiform or a synform? Also, if there is a fold, is it an anticline or a syncline? Keep in mind that the fold may not be pointing straight up.
This index of, well, index fossils should help you figure out the relative ages of the rock (Hint: older fossil = older rock)
http://pubs.usgs.gov/gip/geotime/fossils.html