Since the late 1700's, plate tectonic theory has been argued throughout the scientific community. In the early 1900's Alfred Wegener hypothesized about continental drift and the eventual development of the theory of plate tectonics, but his ideas were not accepted for decades since there was no empirical evidence to support them. Review each point below and sort each one into the columns to represent either "evidence" or an "inference" made by Wegener and other scientists during the development of this theory.

Question

Theory of Plate Tectonics
1. Wegener suggested there was a fit of the South American and African continents.
2. The occurrences of unusual geologic structures and plant and animal fossils found on the matching coastlines of South America and Africa, which were then separated by the Atlantic Ocean. Wegener reasoned that it was physically impossible for most of these organisms to swim or be transported across the ocean.
3. Plate movements over periods of months to decades have been measured directly using extremely precise positioning equipment. Plate movements over millions of years can be estimated from seafloor spreading rates.
4. Confirmation of repeated reversals of the Earth magnetic field in the geologic past.
5. Radiometric dating of the Earth's crust has found that crust in areas where there is sea floor spreading is the youngest crust on Earth.

Answer 1

Here’s how the points can be sorted into "evidence" and "inference":

Evidence:

1. Wegener suggested there was a fit of the South American and African continents.
2. The occurrences of unusual geologic structures and plant and animal fossils found on the matching coastlines of South America and Africa, which were then separated by the Atlantic Ocean. Wegener reasoned that it was physically impossible for most of these organisms to swim or be transported across the ocean.
3. Confirmation of repeated reversals of the Earth magnetic field in the geologic past.
4. Radiometric dating of the Earth's crust has found that crust in areas where there is sea floor spreading is the youngest crust on Earth.

Inference:

1. Plate movements over periods of months to decades have been measured directly using extremely precise positioning equipment. Plate movements over millions of years can be estimated from seafloor spreading rates.

This sorting indicates which points were established as measurable or observable evidence versus those that were inferred interpretations based on that evidence.