(B) Scientists developed the geologic time scale by studying rock layers and index fossils worldwide.
EXPLANANTION:
The sedimentary rocks found in these rock layers are known as strata. These rocks are formed by the three major processes; accumulation, compaction and cementation of sediments. Analysis of these rocks can give the geologists a clear idea about the timescale. Studying its composition, dating, appearance and etc the geologists can easily develop a time scale.
B.) Scientists developed the geologic time scale by studying rock layers and index fossils worldwide. These layers in which the sedimentary rocks are placed, are called Strata, are formed by accumulation, compaction and cementation of sediments. The analysis of the strata, their rock composition, fossil content, disposition, etc., provides valuable data on Earth's past. Dating or absolute age is a numerical value, almost exact. For example, if a rock is said to be 3,000 million years old, it is referring to its absolute age. To know the absolute age of a rock or a stratum, techniques such as radioactive isotope dating must be applied.
