Hi Carter,
As with any long-term process, nobody has time to wait around and watch it happen, but what they can do is drill down through sediment layers and examine them to see how they change with depth. Assuming the lower layers were deposited first, that makes for a good way to study how sediments change as they get buried deeper and deeper. Here is one such article:
http://www.sciencedirect.com/science/article/pii/S0166516215000087
You can find more by Googling “diagenesis borehole study” (without the quotes).
