"Surface sediments" refers to the particles and materials that settle on the top layer of the Earth's surface, such as sand, mud, and rocks. Full definition
The reasons for the high OC in surface sediment of small ponds lacking taliks could be due to slow microbial degradation rates linked to seasonal re-freezing. (journals.plos.org)
Using a satellite - born sensor system that can penetrate through several feet of dry surface sediments, researchers found the dry remains of an ancient river system winding for hundreds of miles below the Saharan sands (scientificamerican.com)
This work from Lidya, members of the Briggs Lab, and collaborators, indicates that marine animals took significantly longer than previously thought to commence major bioturbation (burrowing and mixing) of marine surface sediments. (complex-life.org)