They have been slowly recycled over millions of years.This is called the rock cycle.Sedimentary rocks form when tiny particles of rock that have been weathered and eroded settle out of slow moving ...

Almost all fossils are preserved in sedimentary rock. Organisms that live in topographically ... formed and recycled into other types of rock in a process called the “rock cycle.” This makes the rock ...

The unusual nitrogen isotope values found in sedimentary rocks dating back 2.75 billion ... The research adds to growing evidence that Earth's nitrogen cycle was complex long before the widespread ...

UK—investigated the nitrogen cycle in ancient stromatolites, i.e., sedimentary rocks of organic origin. The ancient rocks, which were around 2.7 billion years old, contain the dead remains of ...