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A total of about 1100 well-distributed samples of suspended matter in surface waters off the length of eastern Asia are available. From these samples, 180 were selected for detailed examination of the non-combustible fraction using optical and electron microscopy along with computer methods of particle measurement and counting. The results showed that, generally, all major components of the suspended matter are most abundant in the nearshore belt (combustible fraction, mineral grains of silt size, skeletal debris, and clay minerals), the result of mechanical transport of detrital sediment and chemical transport of nutrients from the land. Mineral grains of silt size average about 2%, skeletal debris plus clay minerals—23%, and combustible organic matter—75% of total sample weights, but the last two categories vary over a wide range depending upon geographical positions of the samples. Most evident is an oceanward decrease in percentage and concentration of the total noncombustible fraction and an oceanward increase in median diameter of the mineral grains.

About 4100 samples of suspended matter were collected by filtration of surface ocean waters in three large regions on the western sides of oceans and two on the eastern sides. Comparison of results shows that the non-combustible fraction (chiefly detrital clays and silts with some siliceous and calcareous skeletal debris) generally dominates along the western sides of oceans, where large contributions of solid detrital sediment are made by rivers that drain much of the adjacent continents. The combustible fraction also is important off these rivers, but it is more important (both relative to the non-combustible fraction and in absolute terms) along the eastern sides of oceans, where upwelling is intense.

Components of suspended matter in surface waters between western Africa and the Mid-Atlantic Ridge were removed by filtration and measured by scanning electron and optical microscopy. Skeletal debris from diatoms, dinoflagellates, and other plankton are most concentrated in Antarctic surface water and in regions of coastal upwelling. Detrital mineral grains are most concentrated in nearshore regions, from discharge of major rivers, erosion of sea cliffs, and deposition from offshore winds. Farther offshore are high concentrations of mineral grains brought by trade winds from deserts in both northern and southern Africa. The winds also bring freshwater diatoms and woody tissue. The remaining component on the filters is marine organic matter, mostly in thin films. These films trap skeletal debris and mineral grains. Presumably, animals that graze upon the films further concentrate the grains into faecal pellets whose rapid settling carries the grains into deeper waters and to the bottom. The films were found in all other areas of the world ocean from which surface samples were spot-checked: off eastern Asia, off eastern North America, and the central Pacific. Thus they appear to be a major factor in marine sedimentation. In areas of upwelling off western Africa, the total suspended matter in surface waters averages about 0.1 mg/1 of filtrate, about five times that present in the open ocean. It consists of about 70% organic matter, 29.6% skeletal debris, and 0.4% mineral grains, in contrast with concentrations in the open ocean of 90%, 8% and 2%, respectively.

SEM examination of suspended material collected by filtration from samples of surface waters over continental shelves and deeper areas off eastern Asia reveals the presence of irregular organic films that are longer, cover more filter area, and have more tapered edges in samples from nearshore than offshore regions. Associated diatoms include species diagnostic of coastal environments. Films and coastal diatoms are most abundant in waters above continental shelves where river discharges cause the waters to be more dilute than 33.5‰ salinity. Farther from shore, both films and skeletal elements are broken and partly dissolved. Skeletal elements, faecal matter, and other debris are trapped or adhere to the films, which therefore provide a concentrated food source for small organisms beyond nearshore regions of high primary productivity. The films contribute an unknown percentage of the total organic matter that reaches bottom sediments.

The distribution of suspended sediment and plankton throughout the upper 275 m of water over San Pedro Basin, California, was observed on 4 cruises in 1957–58. In general, plankton concentrations varied inversely with depth while suspended sediment concentrations varied inversely with distance from shore. On 3 of the cruises, localized high concentrations of 2-µ diameter sediment were found near the bottom at depths between 200 and 275 m. Evidence of entrainment and subsequent sinking of plankton along with the suspended sediment suggests turbidity currents originating within the upper 50 m on the continental shelf.

A sample of salt-marsh peat from a depth of 59 m at the northwestern margin of Georges Bank has a radiocarbon age of 11,000 ± 350 years. No greater depth or age of salt-marsh peat lying exposed on the ocean floor elsewhere in the world are known to the authors. The age corresponds well with the date of ice retreat from the Gulf of Maine and with the ages of oyster and other shells that mark the advance of the ocean across the bank and the adjacent continental shelf.