Using india's population pyramids into its hypothetical future, how is it possible for a population to continue growing in several generations after women begin to average 2 children each?

One factor that would make it possible is the decrease in the number of deaths, which could be a result of improved health care. In a country which a very low life expectancy in 1970 (50 years) an increase can be achieved easily with small health improvements and in fact it increased to 65 years since 1970s.

Afine-grained igneous rock forms as a result of slow cooling.