some help on stereonet plotting

magsmon

Rank:

Contact:

some help on stereonet plotting

Submitted by magsmon on Wed, 11/30/2011 - 12:09.

I can't seem to imagine how this problem looks like.

- A distinct bed is exposed on a highway road cut. At one end of the cut, the apparent dip of the bed is 32 degrees, 256 degrees. Around a bend in the road, the apparent dip of the same bed is 27 degrees, 125 degrees. Determine the true dip of the bed.

It seems that the azimuthal form of the bearings got mixed up. So in the 1st apparent dip (end of the cut), we have 256 degrees (S76W) as our strike and 32 degrees as our dip? And in the second bearing, we have 125 degrees (S55E) as our strike and 27 degrees as our dip. Are my assumptions correct? so if I sketch them on the wulff net, how would I know the true dip of the bed? Would it be the intersection between the two apparent dips? I'm really puzzled. A little help please. I would really appreciate it ^_^

Login or register to post comments
Send to friend

John

Rank:

Contact:

I'm going to leave this to

Fri, 12/02/2011 - 06:27

I'm going to leave this to someone else. I never really got the hang of plotting on steronets. Sorry.

John

“Civilisation exists by geological consent, subject to change without notice.” - Will Durant

John

“Civilisation exists by geological consent, subject to change without notice.” - Will Durant

geo_girl

Rank:

Contact:

A) are you at university? Or

Fri, 12/02/2011 - 20:41

A) are you at university? Or B) do you ave an email address, if so private message it to me.

If you're at uni the uni can get hold of stereoplot for free. If you can't get hold of it I'll email it to you. Why hurt your brain if the computer can do it for you?

I never got the hang of stereonets, but my structural lecturer was pretty good and let us use stereoplot.

Leah

At first you Mafic I'm basicaly intrusive, but when you get to know me you'll realise I'm orthogneiss.

John

Rank:

Contact:

I'm so glad to hear that

Fri, 12/02/2011 - 22:55

I'm so glad to hear that Leah. I thought I was the only one in the world who found them incomprehensible!

John

“Civilisation exists by geological consent, subject to change without notice.” - Will Durant

John

“Civilisation exists by geological consent, subject to change without notice.” - Will Durant

Lotus

Rank:

Contact:

I'm one of those odd people

Wed, 01/04/2012 - 20:33

I'm one of those odd people that loves stereonets. I know, we exist.

I will say your assumptions are correct with regards the strike (always given in three figures) and dip (always given in two).

I'm going to try and explain it in a logical way so you can do similar problems. The line you draw for the strike represents a plane, a 2d structure. Any one point you select on the that line represents a linear structure. The point where your two lines cross on the stereonet are the points where your two apparent planes are intersecting. Where's the only place this happens? On the true plane.

I'm hoping you know how to read the point back off the net?

Heck this is hard without having the entire thing in front of me.... Give me 24 hours to go away, hunt out of net and construct the problem so I can explain it better!

GeologyRocks