You are walking north across dipping beds in sedimentary rocks.You walk across 200m of rocks with a relatively constant dip of 20 degrees to the south.Suddenly you come to beds with lower dip that become flat lying,and then dip north across a horizontal distance of only about 30m.As you walk on the beds become more steeply dipping until they dip almost 80 degrees to the north.You walk across these steeply dipping beds for 40m,and then beds return to a south dip of about 20 degrees.What kind of structure(s)did you just walk across? (A sketch may help you solve this problem.)

Question

Quizplus · Accepted Answer

The description indicates that the person walked across a sequence of dipping beds that changed dip direction from south to north, then back to south again. This suggests that they were crossing through a fold, where the strata have been bent or warped. The fact that the beds are dipping at different angles and changing direction also suggests that it is an asymmetric fold. The combination of a north-dipping limb followed by a south-dipping limb suggests that the fold is a combination of an anticline and syncline. Therefore, the best choice is C, an asymmetric anticline and syncline.

You Are Walking North Across Dipping Beds in Sedimentary Rocks