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limbs dip toward the center, hinge lines are horizontal or plunging, but straight, youngest rocks in the center |
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limbs dip toward the center, hinge lines are arched, not straight, youngest rocks in the center |
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limbs dip away from the center, hinge lines are horizontal or plunging, but straight, oldest rocks in the center |
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limbs dip away from the center, hinge lines are arched, not straight, oldest rocks in the center |