During Alfred Wegener's time (early 20th century), several key scientific concepts and evidence related to the theory of continental drift were not well understood or accepted. Here are a few notable aspects:
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Plate Tectonics: Wegener proposed the idea of continental drift in 1912, suggesting that continents had once been joined together and had drifted apart over time. However, the mechanism for this movement was unknown to him. The theory of plate tectonics, which emerged in the 1960s, provided the framework that explained how tectonic plates move and interact.
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Seafloor Spreading: The concept of seafloor spreading, which describes the formation of new oceanic crust at mid-ocean ridges and its movement away from the ridges, was not known during Wegener's time. This process is fundamental to the understanding of plate tectonics and continental drift.
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Magnetism and Paleomagnetism: The understanding of the Earth's magnetic field and the record of magnetic reversals in rocks (paleomagnetism) were not developed until later. This knowledge has been crucial in providing evidence for the movement of tectonic plates and the ages of oceanic crust.
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Fossil Evidence: Although Wegener did provide evidence of similar fossil remains across continents that supported his theory, the full significance of biogeography and how it relates to continental drift was not fully understood at the time. The mechanisms of species distribution and evolution played a role, but the theory of plate tectonics later provided the geological context.
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Geological Evidence: The understanding of geological formations and how they relate to tectonic activity was still developing. Wegener did present evidence of matching geological features across continents, but the field was not as advanced in understanding the processes involved in shaping the Earth’s crust.
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Radiometric Dating: Techniques for accurately dating rocks and understanding the Earth's geological history (such as radiometric dating) were not developed until later in the 20th century. This limited the understanding of the timescales involved in the movements of continents.
Overall, while Wegener made significant contributions to the understanding of Earth's geology, many of the scientific principles and technologies that would later support and expand upon his ideas were not available during his time.