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28 FUNDAMENTALS OF PHYSICAL GEOGRAPHY the vast ocean. The belt of ancient rocks of Force for Drifting 2,000 million years from Brazil coast matches Wegener suggested that the movement with those from western Africa. The earliest responsible for the drifting of the continents marine deposits along the coastline of South wascausedbypole-fleeingforceandtidalforce. America and Africa are of the Jurassic age. This suggests that the ocean did not exist prior The polar-fleeing force relates to the rotation to that time. of the earth. You are aware of the fact that the earth is not a perfect sphere; it has a bulge at the equator. This bulge is due to the rotation Tillite of the earth. The second force that was suggested by Wegener — the tidal force — is It is the sedimentary rock formed out of deposits of glaciers. The Gondawana system due to the attraction of the moon and the sun of sediments from India is known to have its that develops tides in oceanic waters. Wegener counterparts in six different landmasses of the believed that these forces would become Southern Hemisphere. At the base, the system effective when applied over many million years. However, most of scholars considered these has thick tillite indicating extensive and forces to be totally inadequate. prolonged glaciation. Counterparts of this successionarefoundinAfrica,FalklandIsland, Madagascar, Antarctica and Australia. Overall Post-drift Studies resemblanceoftheGondawana-typesediments Itisinterestingtonotethatforcontinentaldrift, clearly demonstrates that these landmasses most of the evidence was collected from the had remarkably similar histories. The glacial continental areas in the form of distribution of tillite provides unambiguous evidence of flora and fauna or deposits, like tillite. A palaeoclimatesandalsoofdriftingofcontinents. number of discoveries during the post–World War II period added new information to geological literature. Particularly, the Placer Deposits The occurrence of rich placer deposits of gold information collected from the ocean floor mapping provided new dimensions for the in the Ghana coast and the absolute absence study of distribution of oceans and continents. of source rock in the region is an amazing fact. The gold bearing veins are in Brazil and it is Convectional Current Theory obvious that the gold deposits of the Ghana Arthur Holmes in 1930s discussed the are derived from the Brazil plateau when the possibility of convection currents operating in two continents lay side by side. the mantle portion. These currents are generated due to radioactive elements causing Distribution of Fossils thermal differences in the mantle portion. When identical species of plants and animals Holmes argued that there exists a system of adapted to living on land or in fresh water are suchcurrentsintheentiremantleportion.This found on either side of the marine barriers, a was an attempt to provide an explanation to problem arises regarding accounting for such the issue of force, on the basis of which contemporary scientists discarded the distribution. The observations that Lemurs occurinIndia,MadagascarandAfricaledsome continental drift theory. to consider a contiguous landmass ‘Lemuria’ linking these three landmasses. Mesosaurus Mapping of the Ocean Floor wasasmallreptileadaptedtoshallowbrackish Detailed research of the ocean configuration water. The skeletons of these are found only revealed that the ocean floor is not just a vast in two localities: the Southern Cape province plain but it is full of relief. Expeditions to map of South Africa and Iraver formations of Brazil. theoceanicfloorinthepost–WorldWarIIperiod Thetwolocalitiesare presently4,800kmapart provided a detailed picture of the ocean relief with an ocean in between them. and indicated the existence of submerged Reprint 2026-27