The term ‘marine deposits’ refers to all the materials that are being deposited on the bottom of the sea or ocean. The great bulk of eroded materials from the continents are ultimately deposited on the ocean floor. The great bulk of sediments is brought down and poured into the ocean by the rivers.
Besides, there are other agencies of erosion, transportation and deposition i.e. glaciers, winds, and waves etc. which ‘carry land to water’ where it accumulates in great thickness. In addition to the waste products of sub-aerial erosion, various types of remains of oceanic organisms like marine flora and fauna are also deposited on the ocean floor.
Some of the materials are also brought into water more directly from the interior of the earth through volcanoes, which accumulate on the bottom of the sea or ocean. The sediments laid down on the ocean bottom also include a minute amount of extra-terrestrial material in the form of meteoric dust.
As these materials are classified, and their character is analyzed, much valuable information is gathered regarding the nature of the ocean and the various processes at work within it.
With the help of different kinds of marine sediments, a direct clue is obtained concerning the past climates and all that depends on it.
These sediments, no doubt, provide the most valuable information concerning the climatic changes during the several glacial periods. In determining the age of the oceans, the ocean floor deposits are undoubtedly of great help.
It may be stated that the marine deposits are made of mostly the unconsolidated materials. However, when due to the endogenetic forces there are tectonic disturbances in the earth’s crust, the vast amount of accumulated materials on the ocean floor is converted into hard rocks.
It should be borne in mind that all the sedimentary rocks found on the surface of the earth today were formed out of sediments deposited on the ocean floor. Moreover, all the folded mountains of the world, young as well as old, originated in the shallow, narrow and elongated sea called ‘the tethys’.
The vast thickness of the sediments deposited on its flexible bottom provided the basic materials for their formation. The analysis of the sedimentary rocks helps the geologists in the determination of paleo-climates of the world. It also proves useful in finding out the conditions of the earth’s surface as they obtained in the remote past.
As a matter of fact, the different types of fossils embedded in the sedimentary rocks provide a definite clue to those conditions. As we are aware, the mineral oils are procured from the oceanic deposits.
It is, therefore, very important to know those conditions which produced sediments capable of producing this valuable mineral. Obviously the study of marine sediments proves very significant and useful in exploring the potential areas of petroleum reserves.
The deposition of sediments on the ocean floor, however, is a very slow process. Therefore the rate of sedimentation, the thickness of accumulated deposits and their quantity, if analyzed scientifically, help in the reconstruction of the geological history of the world.
The scientists try to determine the possible age of the earth on the basis of marine sediments accumulated on the ocean bottom.
In fact, the scientific study of oceanic deposits began with the publication of the reports of ‘the Challenger Expedition’ by John Murray and Renard. Thereafter the study of marine sediments made rapid strides.
A number of nations began to send out research vessels equipped with improved oceanographic instruments and observational techniques to determine the physical and chemical behaviour of ocean water as well as the samples of marine sediments.
Because of the recent advances in technology, it has been possible to sufficiently examine the sediments in the deep ocean basins. Now, special apparatus exist for underwater photography and videography to help in situ investigations of the character of ocean floor deposits.
Because of an all-round development in the field of oceanographic researches, the reports of various expeditions are being invariably published which are certainly of immense value in augmenting our knowledge concerning the different aspects of the oceans.