Final answer:
The question addresses how mid-ocean ridges provided evidence for continental drift and plate tectonics. Mid-ocean ridges, such as the Mid-Atlantic Ridge extending into Iceland, illustrate how tectonic plates separate and create new crust, giving insights into Earth's geological history.
Step-by-step explanation:
The question pertains to the evidence of plate tectonics provided by the mapping of mid-ocean ridges in the mid-twentieth century. The concept of continents being part of moving plates was initially brought up by Alfred Wegener with his theory of continental drift. Wegener proposed that continents once formed a giant supercontinent called Pangea.
The evidence for such drift includes the fit of the continents, matching fossils and geological formations across oceans, as well as paleoclimatic evidence indicating changes in the proximity of continents to the polar regions and the equator.
Mid-ocean ridges are places where tectonic plates are separating, and new crust is being created by volcanic activity.
The phenomenon of rocks around these ridges having reversed magnetization with increasing distance from the ridge signifies periodic reversals of Earth's magnetic field over geological time. The study of these magnetic patterns, along with the known spreading rates of the ridges, helps researchers reconstruct the historical record of Earth's magnetic field.
Mid-ocean ridges do indeed appear to extend into continents. For example, the Mid-Atlantic Ridge extends into Iceland, which sits right atop the ridge and experiences high volcanic activity as a result. Understanding these geological features and their extensions into continents assists geologists in piecing together the historical movement of Earth's continental plates.