What do you mean? that is not can be answered
In geology, a graded bed is one characterized by a systematic change in grain or clast size from one side of the bed to the other. Most commonly this takes the form of normal grading, with coarser sediments at the base, which grade upward into progressively finer onesI just learned about this in our rocks and minerals unit for science,
Carbonate groups contain a single carbon atom, and three oxygen atoms in a trigonal molecular geometry. The carbon atom has two single bonds to two oxygen atoms and a double bond to the third oxygen atom. Therefore, in addition to carbon, carbonate minerals contain oxygen. An example of a carbonate mineral is calcium carbonate, often found within rocks.