please answer in full detail/respond to all parts of question: 5. imagine that y
ID: 804303 • Letter: P
Question
please answer in full detail/respond to all parts of question:
5. imagine that you are taking a field course in the Alps, from geologic cross sections, you expect to find some very large folds(see what is happening in this picutre?) where the rock layers have been bent over backward. what kinds of evidence could you look for that would help you deterime whether a particular sequence of rock is right side up or upside down? in other worrds, how would you determine whether a trough- shaped fold was a right side up syncline or an upside down (i.e. overturned ) anticline???
Explanation / Answer
Syncline is a fold that in convex in the direction of the oldest bed in the sequence. Normally these are trough shaped fold but they can also be oriented upright. Similarly anticline is a fold that is convex in the direction of the youngest bed in the folded sequence. Commonly they are upright, convex upward but they can also be upside down anticlines. Overturned folds are those which is rotated beyond vertical so that the facing direction of the limb points downward at some angle.
There are some evidence which helps to identify the overturned folds whether it is upside down anticline or right side up syncline. In this drag folds are very useful guides. Drag folds are the asymmetric minor folds formed in the soft and incompetent beds between the harder and more massive limbs of the major folds. The change in the asymmetry of these minor folds from Z to S or S to Z can be used to determine the orientation of the fold. These drag folds reflect the sense of sense of layer parallel slip on each fold. When the asymmetry of drag folds is in opposite to the sense of bedding plane movements of the limbs of the fold the fold is not an anticline. Whereas the drag fold sense of movement is in the same direction with the sense of movement of the limbs of the fold it is an overturned syncline.
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