Journal #62 After putting the continental pieces together on Friday, what did you notice about the continents? What did you notice about the fossils? What is Pangaea?

Today, we will describe the hypothesis of continental drift and the process of sea-floor spreading

Observations were made more than 400 years ago. Continental Drift Observations were made more than 400 years ago. Mapmakers brought back information about new continents and their coastlines. They used this information to make maps People were impressed by the similarity of continental shorelines on either side of the Atlantic Ocean. The continents looked they would fit in a puzzle.

Wegener’s Hypothesis A scientist named Alfred Wegener proposed a hypothesis known as continental drift. Continental drift states that the continents once formed part of a single landmass or supercontinent. This supercontinent began breaking up into smaller continents about 250 mya. During which Era did this occur?

Wegener’s Hypothesis Over millions of years, these continents drifted to their present locations. The crumpling of the crust in places have produced mountain ranges. Andes on the western coast of South America

Fossil Evidence When you put your continental puzzle pieces together, what did you notice about the fossils? In addition to similar coastlines, Wegener found other evidence that supported continental drift Fossils of the same plants and animals were found in areas that had once been joined.

Fossil Evidence Example: Mesoaurus, a small reptile found in both South America and western Africa. It is unlikely that these reptiles swum across the Atlantic ocean. There was no evidence of bridges. Therefore, South America nd Africa had been joined at one time.

Evidence from Rock Formations Geological evidence also supports Continental Drift. The ages and types of rocks in the coastal regions of widely separated areas matched closely. Example: Western Africa and Eastern South America and similar rocky types that were the same age. Mountain chains (that ended at the coastline of one continent) continued on other continents across the ocean. (page 240)

Climatic Evidence Changes in climatic patterns also support continental drift. Geologists found layers of debris from ancient glaciers in southern Africa and South America. Today, those areas are too warm for glaciers.

Video on Continental Drift

What is continental drift? Let’s Review Who was the scientists that proposed the hypothesis of continental drift? What is continental drift? What fossil evidence supports continental drift? What rock evidence supports continental drift? What climatic evidence supports continental drift?