Which of these is the most characteristic feature of a sedimentary rocks?
a) stratification
b) crystallization
c) brightly colors
d) the presence of shells

The answer to this item is letter A. Stratification

The word refers to how the layers of sediments are stacked over another layer. This sediments can range from hundreds or meters to only submillimeter scale. The stratification is the most fundamental feature of the sedimentary rocks. 

The small scale stratification is a result of different kinds of stratification and alternating process of deposition in the same or similar environment. There are several types of stratification: (1) cross-bedding, (2) graded bedding, (3) ripple marks, etc. 

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