Chapter 2 - Section 2.2 - Continental Drift: An Idea Before Its Time - Concept Checks - Page 42: 1

The first line of evidence that led early investigators to suspect that the continents were once connected was the observation of the remarkable fit of the coastlines of Africa and South America.

Certainly! Here are the steps that early investigators followed to identify the first line of evidence suggesting the continents were once connected: 1. Observation of Coastline Fit: Early investigators, such as Abraham Ortelius in the 16th century and later Alfred Wegener in the early 20th century, carefully examined maps and noticed that the coastlines of South America and Africa seemed to fit together like puzzle pieces. This observation sparked their curiosity and raised questions about the possibility of the continents being connected in the past. 2. Collection of Additional Geological Data: Investigators began collecting geological data from different continents, including rock types, mountain ranges, and fossil evidence. They compared the similarities between corresponding regions on different continents, such as the Appalachian Mountains in North America and the Caledonian Mountains in Europe. 3. Matching Geological Features: By comparing the geological features, investigators found striking similarities in rock formations, structures, and geological sequences on different continents. For example, they observed similar layers of sedimentary rocks and identical fossil species on continents that were supposedly separated by vast oceans. 4. Reconstruction of Supercontinent: Based on the evidence gathered, investigators proposed the hypothesis of a supercontinent, which they called "Pangaea," meaning "all lands." They postulated that the continents were once united into a single landmass and later drifted apart. 5. Development of the Theory of Continental Drift: The observations of the fit of coastlines, the matching geological features, and the concept of a supercontinent led to the development of the theory of continental drift. Alfred Wegener, in 1912, presented this theory, suggesting that the continents were once connected and had moved over geological time. These steps illustrate how early investigators used observations, data collection, comparisons, and the formulation of a hypothesis to uncover the first line of evidence supporting the idea of continental connection and ultimately lay the foundation for the theory of continental drift.