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

them. What is this interlimb angle ? ______________b) Mark the point half way between the poles along the great circle connectingthem (this is the fold bisector). Fit a great circle to fold bisector and the foldaxis. This plane approximates the axial surface for folds that are not tooasymmetric.What is the strike and dip of the axial surface of the fold?____________________c) Using your field map and analysis , make an accurate geologic cross section ofthe Baldy structure. Do not make a topographic profile, just draw the structuralcross-section to scale. Keep the horizontal and vertical scale the same.d) Lastly, describe the type of fold you mapped (your description should usealmost all of the words covered in class)Part II: Attitude of Folds in the Cascades:Just a few weeks ago, the class went the Cascades, near French Cabin Creek,and recorded a number of strikes and dips of folded meta-sedimentary rocks, as wellas attitudes of fold axis and axial surfaces.The present day structure of the Washington Cascades is dominated by abroad, deeply eroded north-south anticlinorium. This young structure upwarps asystem of older, tighter, northwest-southeast folds and faults (part of the systemthat formed the Mt Baldy anticline).In this part of the problem you will determine the present-day attitude of foldsin the French Cabin Creek region of the Cascades. By comparing the attitude of thesemultiply deformed folds to the attitude of the Mt Baldy fold, we will be able to talkabout the younger event.1) Finding the fold axis of folds in the French Cabin Creek region:plotting dataa) Using the stereonet program, Plot all the bedding attitudes as POLES TOPLANES. Fit a great circle to your data.What is the attitude of this great circle? _________________________c) Plot the pole to this great circle and mark it prominently with a "+".What is the attitude of this pole? _________________________