I am pretty sure the answer is all of the above, D
A downward arching rock layer is called syncline.
Explanation:
Syncline and anticline are words used to design folds based on the analogous ages of folded rock layers. A syncline is a fold in which the modern rocks happen in the core of a fold. Where rock layers have been changed prior to folding, such as by folding about a giant fold with a shallowly inclined axial surface, the dearest rocks now occur in the core of folds where layers slide towards the fold axis.
A downward arching rocklayer is called a syncline. It is a type of fold that is characterized by its downward-facing axis.
Synclines are typically formed when sedimentary rocks are subjected to compressional forces. The compressional forces cause the rocks to bend, forming the downward-facing axis.
Synclines are often found in sedimentary basins, which are areas where sediment has accumulated over time. The sediment is typically deposited in horizontal layers, but the compressional forces can cause the layers to bend, forming synclines.
Synclines can be identified by their characteristic shape. They are typically bowl-shaped, with the axis of the fold running through the center of the bowl.
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