Deep Sea Drilling

Brielle Colemon

Westwood College

Chapter 5 Summary

July 15, 2010

Most geologists believed a century ago that the geographic positioned of the ocean basins and continents were fixed. Earths scientist now realizes that the continents gradually migrate across the globe. In short, a revolutionary new model of earth’s tectonic process has emerged. This is profound reversal of scientific understanding and has been appropriately described as a scientific revolution. The revolution began as a relatively straight forward proposal by Alfred Wegner, called continental drift.

Continental Drift

Is an idea before its time. The idea that continents particularly South America and Africa fit together like pieces of a jigsaw puzzle originated with improved world maps, however little significance was given to this idea until 1915. Wegner suggested that a supercontinent began breaking into smaller continents when than drifted to their present positions.

Evidence: The Continental Jigsaw Puzzle

Scientist have determined that a much better approximation of the time outer boundary of the continents is the seaward edge of the continents shelf, which lies submerged several hundred meters below sea level.

Evidence: Fossils Match across the Seas

Wegner learned that identical fossils or organisms were known from rocks in both South America and Africa. Wegner learned that most paleontologist were in agreement that some type of land connection was needed to explain the existence of the identical fossils of the Mesozoic life forms on widely separated landmasses.

Mesosaurus

The classic example is Mesosaurus an, aquatic fish catching reptile whose fossils remains are found only in black shale’s of the Permian period in eastern South America.

Evidence: Rock types and Structures Match

The continents were once together, the rocks found in a particular region on one continent should closely match in age and type. Those fossils found in adjacent positions on...