Problem Set #4: Folds and Folding Stereonet Analysis Due Tuesday ...

3) Another way to get a handle on the axial plane.a) Plot the pole to the axial surface that you determined is step 2Now plot the poles to fold planes that were measured in the field, and the polesto bedding.Notice that all of these poles fall near a great circle- thus they all have about thesame strike, but just have different dips. Draw a great circle through the clusterof poles. Now, determine the pole to the circle. The trend of the pole is theapproximate strike of all these planes. What is the average strike of themeasured fold planes? ____________________What is the range of dips of the fold planes? _____________________b) Now, look at the attitude of the axial plane you determined in part 2 above. Dothe two attitudes match? Why or why not?If not, rethink step c-d above, and recognize that there are two interlimb angles.Now, redo steps c-d, using the other interlimb angle. What is the new calculatedattitude of the axial plane?______________________________c) Looking at your plot of poles to bedding, and poles to the fold planes, again seehow they all fall near a great circle, they are all just planes with different dips.Now, try to visualize parasitic folds on a larger fold, imagine how the axial planesof these parasitic folds could have the same strike, but different dips. Try anddraw a picture of this.b) Now make another plot with all of the above poles, and add the poles to foliation.Knowing the relationship between foliation of fold planes, make another sketchshowing the attitudes of parasitic folds, fold axis, and foliation.Part III: Describing the most recent folding in theCascadesThe attitude of the Mt Baldy fold is somewhat representative of folds formed inthe Neogene. This period of folding affected rocks throughout the region, includingrocks in the Cascades.Subsequently, another folding event has affected the rocks in the Cascades. By