Geologists study ancient sedimentary rocks to determine what sedimentary environment they formed in. Determining ancient environments is very important to understand the history of the Earth. It helps geologists understand how the Earth’s surface has changed over time. Since most ancient organisms live around environments where sedimentary rocks are formed, paleontologists need to know the ancient environments.

One way to study environments is to compare the sedimentary structures in ancient rocks with sedimentary structures forming at present in modern sedimentary environments. From looking at today’s environments, geologists can learn how sedimentary structures form. If the rock shows the same sedimentary structure as the modern sediment, then the rock probably formed in the same way. This is an important way of understanding what happened in the past, even if the deposition occurred millions of years ago.

Sand ripples along beach in South Carolina

Ripples preserved in sandstone