Examination of the globe usually results in the observation that most of the continents seem to fit together like a puzzle (Plate pp). For example, the west African coastline appears to snuggle into the eat coast of South America and the Caribbean sea, and a similar fit appears across the Pacific (Plate pp). The fit is even more evident when the submerged continental shelves are compared rather than the coastlines (Plate pp).

In 1912, Alfred Wegener, 1880-1930, noticed this same thing and proposed that the continents were once compressed into a single proto-continent that he called Pangaea, meaning "all lands," and over time they have drifted apart into their current distribution (Plate pp). Wegener bel

ieved that Pangaea was intact until about 300 million years ago during the late Carboniferous period, when it started to break up and drift apart (Plate pp). However, his hypothesis lacked a geological mechanism to explain how the continents could drift across the earth's surface as he proposed (Plate pp). Wegener's inability to provide an adequate explanation of the forces responsible for continental drift and the prevailing belief that the earth was solid and immovable resulted in the scientific dismissal of his theories (Plate pp).

Today, scientists have a fairly good understanding of how the plates move and how such movements relate to earthquake activity (Understanding pp). The majority of movement occurs along narrow zones between plates where the results of plate-tectonic forces are most evident (Understanding pp). The four type of plate boundaries are:

The zone between two plate sliding horizontally past one another is called a transform-fault boundary, or simply a transform boundary, a concept originated with Canadian geophysicist J. Tuzo Wilson, who proposed that these large faults or fracture zones connect two spreading centers, called divergent plate boundaries, or, less commonly, trenches, called convergent plate boundaries (Understanding pp). The majority of transform faults are found on the ocean floor and commonly offset the active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes (Understanding pp).

as the plates pull away from each other.

The consequences of plate movement are easy to recognize around Krafla Volcano, in the northeastern part of Iceland, where existing ground cracks have widened and new one appear every few months (Understanding pp). From 1975 to 1984, numerous episodes of surface cracking, called rifting, took place al

Some common words found in the essay are:
Hess Deitz, Alfred Wegener, Krafla Volcano, Plate Tectonics, Earth Understanding, Arthur Holmes, Harry Hess, Tuzo Wilson, African Plates, San Andreas, understanding pp, plate pp, story pp, ocean floor, transform faults, plate boundaries, boundaries crust, fracture zones, zone understanding pp, zone understanding, plate tectonics, earth understanding pp, understanding pp majority,
Approximate Word count = 1237
Approximate Pages = 5 (250 words per page double spaced)