Studies of cores of deep ocean sediments show that. First, the composition and geographic distribution of the source materials of marine sediments are dominated quantitatively by terrigenous debris, pyrogenic debris and biogenic debris, which is the dominant sediment source when the first two are lacking. Second, the alteration of these source materials during their residence in the ocean depends on the three-dimensional variations in the geochemical environment of the ocean and the residence time of the sourceContribution of Scripps Institution of Oceanography materials in these environments. Third, changes in the sediments after burial in the marine environment are dominated by advection of the interstitial water component and its dissolved chemical species, and by the effects of increase in confining pressure and temperature on the deposited materials. Fourth, after deposition, plate motion tends to move sediments from the site of their deposition horizontally away from ridge crests into deeper water. A vertical succession of marine sediments represents not only consecutive paleo-environments, but different parts of those environments. These general principles together form a suite of criteria which permit the reconstruction of paleo-environments.
Almost all that we know about materials beneath the seabed we have discovered during the last twenty years, and much of that during the brief history of the JOIDES Deep Sea rilling Project. This burst of knowledge is revolutionizing our understanding of the distribution and genesis of crustal materials. It cannot have other than an explosive impact on our se8;rch for and production of resources under the seabed. Delegates to this Convention represent organizations responsible for utilizing resources in and beneath the oceans, and I am especially delighted to have this opportunity to summarize for you some of the ways that ocean drilling is changing our understanding of the nature, the distribution and the genesis of marine sediments.
The history and success of the cruises of the D/v GLOMAR CHALLENGER are already well known to the Society of Marine Technology [27]. The National Science Foundation, Scripps Institution of Oceanography, and Global Marine Incorporated were honored last year by this organization for their contribution to these successes. The D/v GLOMAR CHALLENGER is now completing her 16th voyage (Figure 1). By the end of Leg XIV December 1, 1970 she had drilled a total of 230 holes at 144 sites. 58,000 meters of hole had been drilled and 10,000 meters of core recovered.
Studies of these cores are yielding greater understanding of the four major factors which govern the present nature and distribution of marine sediments:
the composition and geographic distribution of'; source materials,
alteration of these materials during their residence in the ocean,
post-depositional diagenetic changes, and
the post depositional horizontal and vertical movement of sediment deposits by plate motion and other tectonic forces.
