Beds are a type of these structures that are separated by bedding planes. For 10 points each:
[10m] Geological folds arise from the bending of series of these structures. The law of superposition gives that, in the absence of deformation, these layers are in order by their age.
ANSWER: strata [or stratum]
[10e] Many folds consist of deformed strata of this class of rocks that include chalk and sandstone.
ANSWER: sedimentary rocks
[10h] This type of fold is convex down and features the older strata nearer to its center. Petroleum is often found in “structural traps” resulting from natural cavities that can form under these folds.
ANSWER: anticlines [prompt on upfolds]
<Benjamin Chapman, Science - Earth> ~21096~ <Editor: David Bass>