Drifting lands increasing grade update#

Related: Plate tectonics are 3.6 billion years old, oldest minerals on Earth reveal (opens in new tab) What evidence is there for continental drift? Magnetic (opens in new tab) minerals aligned in ancient rocks on continents also showed that the continents have shifted relative to one another. Alternating patterns of magnetic anomalies on the ocean floor indicated seafloor spreading (opens in new tab), where new plate material is born. In the 1960s, scientists discovered plate edges through magnetic surveys of the ocean floor and through the seismic listening networks built to monitor nuclear testing, according to Encyclopedia Britannica (opens in new tab).

Drifting lands increasing grade update#

Plate tectonics is like a modern update to continental drift.

For instance, as geophysicists began to realize that continental rocks were too light to sink down to the ocean floor, prominent paleontologists instead wrongly suggested that the similarities between fossils had been overestimated, Frankel said. Researchers argued over the land bridges right up until the plate tectonics theory was developed from the 1950s to the 1970s, Frankel said. And to account for the identical fossils discovered on continents such as South America and Africa, scientists invoked ancient land bridges, now vanished beneath the sea. They thought Earth's incredible mountains were created because our planet had been cooling and shrinking since its formation, Frankel said. When Wegener proposed continental drift, many geologists were contractionists.