INDIAN GEOGRAPHY

Detailed explanation-1: -The formation of three main types of rocks (igneous, metamorphic and sedimentary) can take from 1 day to millions of years. Intrusive igneous rocks can crystallize thousands of years, while extrusive rocks just a few days. It takes millions of years to form sedimentary and metamorphic rocks.

Detailed explanation-2: -The process of sedimentary rock formation takes millions of years to complete only to begin a new cycle of rock formation.

Detailed explanation-3: -In general, about 30 cm of sedimentary rock are deposited over a period of 1, 000 years. However, any given sedimentary layer that is being studied may not have been deposited at an average rate.

Detailed explanation-4: -Earth’s oldest sedimentary rocks, found in Greenland, are about 3.9 billion years old. Unusual chemical traces in these rocks may suggest that life existed when they formed. Image courtesy of Dr.

Detailed explanation-5: -The oldest-known sedimentary rocks on the Earth comprise the 3.8-billion-year-old Isua Sequence of southwestern Greenland. The rocks were once sediments formed by chemical precipitation from ocean water.