What was unknown to scientists during Wegner's time
During Wegener's time, there were several things that were unknown to scientists:
1. The exact mechanism of how continents move and what drives their movement was not known. Wegener proposed the theory of continental drift, but the mechanism behind it was not understood until the discovery of plate tectonics in the 1960s.
2. The concept of sea-floor spreading, which explains the creation of new oceanic crust at mid-ocean ridges, was not known. This process was discovered in the 1960s and provided additional evidence for plate tectonics.
3. The nature of Earth's interior and its layering was not well understood during Wegener's time. It wasn't until the development of technologies like seismic tomography and the study of earthquake waves that scientists gained a better understanding of the internal structure of the Earth.
4. The concept of plate boundaries and the different types of plate interactions (such as convergent, divergent, and transform boundaries) were not fully understood. This understanding emerged after Wegener's time with the development of plate tectonics theory.
5. The role of convection currents in the mantle, which is now recognized as the driving force behind plate tectonics, was not known during Wegener's time. It was only later, with the development of the theory of mantle convection, that scientists could explain how the movement of material within the Earth's mantle contributes to the motion of tectonic plates.
Overall, Wegener's theory of continental drift laid the foundation for our understanding of plate tectonics, but many of the details and mechanisms were still unknown during his time.
During the time of Alfred Wegener (early 20th century), several aspects of plate tectonics and continental drift were not yet known or understood by scientists. Some of the key unknowns during Wegener's time include:
1. Mechanism of Plate Movements: Although Wegener proposed the concept of continental drift, he could not provide a satisfactory mechanism to explain how continents moved. The understanding of mid-ocean ridges, subduction zones, and convection currents in the Earth's mantle as driving forces for plate movement came much later.
2. Seafloor Spreading: The idea of seafloor spreading, whereby new oceanic crust forms along mid-ocean ridges and moves away from each other, was not known during Wegener's time. This concept, put forth by Harry Hess in the 1960s based on studies of magnetic anomalies on the seafloor, provided further evidence for plate tectonics.
3. Plate Boundaries: The specific types of plate boundaries - divergent, convergent, and transform - were not yet well-defined during Wegener's time. The understanding of the different types of plate boundaries and their associated geological features was developed later with the advancement of seafloor mapping and global seismic monitoring.
4. Paleomagnetism: The understanding of Earth's magnetic field and its role in paleomagnetism was not fully grasped during Wegener's time. It wasn't until the mid-20th century that advances in studying rock magnetism and the recognition of magnetic reversals in oceanic crust supported the theory of continental drift.
Overall, while Wegener's ideas laid the foundation for the theory of plate tectonics, many important aspects that are now known to scientists were not yet understood during his time.
During Wegener's time, scientists were unaware of the mechanism that could explain how continents move and what forces are responsible for their motion. This concept, known as plate tectonics, was not fully understood or accepted at the time. In the early 20th century, Wegener proposed the theory of continental drift, which stated that the continents were once joined together in a single landmass and gradually moved apart over time.
However, Wegener's theory lacked a convincing mechanism that explained how the continents moved. As a result, many scientists were skeptical of his ideas and they were not widely accepted until several decades later.
It wasn't until the 1960s and 1970s that plate tectonics became widely accepted. This theory explains that the Earth's lithosphere (the rigid outer layer) is divided into several large plates that float on the semi-fluid asthenosphere below. These plates are in constant motion due to convection currents in the mantle and interact at plate boundaries, leading to various geological phenomena such as earthquakes, volcanic activity, and the formation of mountains.
Plate tectonics provides a comprehensive explanation for the movement of continents and has become the fundamental understanding in modern geology. However, during Wegener's time, this crucial mechanism was still unknown to scientists.