What Are Earth Layers Made Of?
As a result of studies during the past century, geologists have a pretty clear sense of what the layers inside the Eart…
The Discovery of Sea-Floor Spreading
Military needs during World War II gave a boost to sea-floor exploration, for as submarine fleets grew, navies required d…
Evidence for Sea-Floor Spreading
Marine Magnetic Anomalies Recognizing anomalies For a hypothesis to become a theory, researchers must demonstrate that …
What Do We Mean by Plate Tectonics?
The paleomagnetic proof of continental drift ( plate tectonics ) and the discovery of sea-floor spreading set off a scie…
Convergent Plate Boundaries and Subduction
At convergent plate boundaries, two plates, at least one of which is oceanic, move toward one another. But rather than …
Transform Plate Boundaries
When researchers commenced to explore the bathymetry of midocean ridges in detail, they observed that mid-ocean ridges …
How Do Plate Boundaries Form and Die?
The configuration of plates and plate boundaries visible on our planet today has not existed for all of geologic history…
What Drives Plate Motion, and How Fast Do Plates Move?
We've now discussed the many facets of plate tectonics theory but to complete the story, we need to address a major…