12/23/2023
One of the things that is so cool about sedimentology is determining the source of the fragments within a particular deposit. We look at modern analogs to see a region where sediments *could* come from.
Here is a picture of modern-day USA, showing major drainage basins. The dominant one is, of course, the Mississippi River system. About one third of all the sediments in North America work their way through the mouth of the river. Notice, however, that the Rio Grande drains a different region; hence the sediments in its mouth and offshore will be different than its neighbors to the east.
Geologists use information like this to “re-build” old landscapes and geomorphology from times in the past, even when the continents occupied different locations on Earth and in relation to each other. From a picture like this, it is easy to see why sediments in North America were sourced from places like Africa about 200 million years ago.
