Why oil exploration geologists look for sorted and rounded sediments?

Problem Set 2
Geology 102
Name:
1. Imagine that you’re observing red-colored sandstone with well-rounded grains. What information can you tell me about this rock? I’m looking for erosional and depositional histories, past location, composition, etc.
Well-sorted sandstones usually consist of well-rounded grains that are texturally mature. The roundness indicates that the grains have spent a long time in the transportation cycle. During erosion, Random abrasion occurs, leading to the eventual rounding off of all the pointed edges and corners of grains. Therefore, round grains are indicative of the duration sediment has been in the transportation circle. As erosion continues, smaller clasts are carried away while larger ones are left behind. As the weathering process persists, unstable mineral grains near the surface lessen with the increase of transport distance and time in the cycle.
461962546005752. Normally, the principle of superposition suggests that older rocks are located beneath younger rock...