Exploration of continental shelves and slopes requires a thorough understanding of the implications of the sea-floor-spreading hypothesis. If the Americas and Eurafrica once were joined, as sea-floor spreaders allege, no great intellect is required to see that the geology of the circum-Atlantic shelves and slopes would be different than if the Atlantic Ocean had always existed. Most sea-floor-spreading advocates believe that the Atlantic basin first opened during Jurassic or Early Cretaceous time. If true, drilling for pre-Jurassic objectives in certain areas is senseless. However, if sea-floor spreading has not taken place, pre-Jurassic objectives may underlie almost all shelf and slope areas. Similar conclusions can be made for the shelves and slopes surrounding the Ind an Ocean.

Sea-floor spreading also would affect the circum-Pacific margins, which should contain strongly deformed post-Jurassic sediments. Drilling objectives in the circum-Pacific shelves should be mainly in young strata, principally of Tertiary age. This seems to be true around most of the Pacific rim, and sea-floor-spreading proponents cite the youthful geology of the circum-Pacific as evidence for their viewpoint.

Although the problem of sea-floor spreading is unusually complex, the problem can be summarized simply: can the hypothesis be proved or disproved? The correct answer to this question will affect world mineral economics for decades to come.

Numerous facts of geology and geophysics contradict the hypothesis of sea-floor spreading. A combination of Ushakov's, Talwani et al.'s, and Melson et al.'s models of the mid-ocean ridges explains the linear magnetic anomalies of the ridges, their topography, the distribution of rock types on the ridges, their gravity expressions, and the Sykes' "transform-fault" solutions on the basis of known processes, as opposed to inferred processes. G. D. Afanas'yev's discovery that most metamorphic rocks of the Indian Ocean ridge system have Proterozoic (Riphean) and Paleozoic K-Ar dates severely damages the sea-floor-spreading concept as it has been applied in the Indian Ocean. Rezanov has proved that paleomagnetic methods cannot be used to determine ancient polar positions, or to demonstrate ontinental separations. Maxwell's, Glangeaud et al.'s, and Watson and Johnson's studies of the Mediterranean Sea region eliminate both spreading and closing of that sea since late Paleozoic or earlier time. A problem which is even more baffling is that of the immaculati: i.e., the presence of flat-lying, undeformed sediments in parts of the deep ocean basins where strong deformation is predicted by sea-floor spreading. Such areas include (1) fracture zones which cross the mid-ocean ridges (undeformed sediments as old as Paleocene are exposed in these fracture zones), (2) abyssal plains, (3) continental slopes and rises (except for gravity-slide blocks), and (4) island-arc trenches. Why does a strongly deformed Early Jurassic to Eocene fold belt extend from the Cape Verde Islands to Tunis a? How does one account for the presence of bathyal to abyssal Jurassic sediments in the Cape Verde Islands, beneath the Hatteras Abyssal Plain, and elsewhere?

Almost conclusive evidence against sea-floor spreading comes from the fields of climatology, meteorology, and biology-paleontology. The field of meteorology is particularly critical, but few geologists, geophysicists, or oceanographers have studied this science. Salomon-Calvi, one of Wegener's staunchest advocates, concluded before his death that widespread continental glaciation would be impossible without an adequate supply of moisture and, therefore, that separation of the southern continents was essential from Mississippian through Permian times. Rukhin's recent analysis of late Paleozoic tillite distribution is even more conclusive because of the wealth of climatology data available to him.

To test Salomon-Calvi's and Rukhin's conclusions, the writer prepared detailed maps of coal, evaporite, and tillite distributions by age and epoch from late Proterozoic time to the present. The evaporite-coal-tillite distribution patterns shown on the maps differ appreciably from previously published compilations, and coincide very closely with the distribution pattern of modern deserts, evaporites, peat bogs, and till deposits. Meteorological and ocean-current analyses of these maps show that the distribution of these rock types requires, for the past 1 billion years, an ocean basin-continent distribution nearly the same as that of today. If the continent and ocean-basin distribution of the past was significantly different from that of today, the distribution patterns of pre-Holocene evaporites, coals, and tillites cannot be explained. The maps even show that the position of the horse latitudes has not changed appreciably for 1 billion years. The maps do not eliminate some polar tilting since Proterozoic time, but such tilting is not required to explain the patterns.

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The paleoclimatic and paleometeorologic conclusions which can be made from the maps are confirmed independently by Stehli's species-diversity gradients and by Axelrod's tree-ring distribution studies. Additional support includes: (1) A single Jurassic climatic and floral province extends from the Ust-'Urt Plateau, on the eastern side of the Caspian Sea, onto the Indian shield. (2) The late Paleozoic sequence of the northern Indian shield is remarkably like that of the Tarim basin of China; the faunas and floras are nearly identical; and both can be mapped across the Himalayas; therefore, India has been part of the Asian continent since mid-Paleozoic time; the presence in India and much of the central Himalayas of Late Pennsylvanian tillites can be understood in terms of the effects of a cold world climate on the monsoons of the Indian Ocean. (3) Many of the Late Pennsylvanian and/or Early Permian glacial deposits of the Andes, of Brazil, of Suid-West Afrika, and of India, are mountain glaciers, as Martin, Grabert, and others have shown. (4) Pennsylvanian and Permian reefs flourished in southern Chile. (5) The "Nubian" desert sandstone--from Spanish Sahara to Iran--remained in the same position relative to the equator from Cambrian through Holocene time. (6) Smiley's floral zones from Holocene through Triassic time parallel the present equator.

These and many additional facts from field geology and from paleozoological-paleobotanical studies refute the spreading-sea-floor hypothesis. The writer concludes that continents and ocean basins have maintained the same relative positions for at least 1 billion years. Exploration of the shelves and slopes, therefore, should proceed on this premise.

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