The research suggests, for example, that finding pristine mantle material in the middle of the basin might be a bit tricky because of the large volcanic deposit. (spaceref.com)
Extensive underwater volcanism during ridge spreading led to rapid alteration of volcanic deposits and major changes in ocean chemistry. (sciencedaily.com)
Much of this clay is harvested from large volcanic deposits in Fort Benton, Wyoming (thus the name), but it is also harvested from the Montmorillon region in France (again, thus the name) and several smaller deposits worldwide. (wellnessmama.com)