Ch. 2

A theory which proposes that Earth’s outer shell consists of individual plates that interact in various ways and thereby produce earthquakes, volcanoes, mountains, and the crust itself

A hypothesis, credited largely to Alfred Wegener, which suggests that all present continents once existed as a single supercontinent. Further, beginning about 200 million years ago, the supercontinent began breaking into smaller continents, which then “drifted” to their present positions

A large landmass that contains all or nearly all of the existing continents

The proposed supercontinent that 200 million years ago began to break apart and form the present landmasses

The continental jigsaw puzzle Fossil matching across the seas Rock types and geologic features that matched across continents (mountain ranges) Ancient climate (Paleoclimatic)

Inability to identify a credible mechanism for continental drift Incorrectly suggested that the larger and sturdier continents broke through thinner oceanic crust

A coherent unit of Earth’s rigid layer that includes the crust and upper unit

Divergent plate boundaries Convergent plate boundaries Transform plate boundaries

A boundary in which two plates move apart, resulting in upwelling of material from the mantle to create a new seafloor

A continuous elevated zone on the floor of all the major ocean basins and varying in width from 500 to 5000 kilometers. The rifts at the crests of ridges represent divergent plate boundaries

A long, narrow trough bounded by normal faults. it represents a region where divergence is taking place

A hypothesis, which suggests that new oceanic crust is produced at the crests of mid-ocean ridges, which are the sites of divergence

It becomes old, cold and low as the seafloor spreads