It contains rocks covering almost the entire spectrum of the Geological Time Scale. It has rocks severely deformed and metamorphosed as well as recently deposited alluvium which are yet to experience diagenesis. Even the fossil record is extremely diverse and includes the earliest stromatolites, invertebrates, vertebrates and plant fossils. Rock type and mineral deposits of many varieties can be found in this country. Such a diverse and complex geology needs to be studied very systematically.
Stratigraphy covers study of rocks of a region and tracing down the geological history.
Rocks as they occur now in the field have gone through some of the events like deposition, compaction, deformation, metamorphism and erosion. Some may experience many phases of deformation and metamorphism. Most of these events depend on the tectonic activities this part of the earth's crust has witnessed over the ages. Although erosion and later phases of tectonism tend to erase the past, we can still get some evidence of the past tectonic activities through study of rocks. From whatever idea we have, we can build tectonic framework of India and study each unit separately.