1957-1961 Local interests dredged a channel across Padre Island and constructed two tetrapod jetties at the entrance to the Gulf of Mexico. The north and south jetties were 1,600 and 800 ft long, respectively, and spaced 1,000 ft apart.
The following four timelines show the geologic time scale. The first shows the entire time from the formation of the Earth to the present, but this compresses the most recent eon. Therefore, the second scale shows the most recent eon with an expanded scale. The second scale compresses the most recent era, so the most recent era is expanded in the third scale.
1 Use the links in the time machine below and explore a specific period that interests you. 2  Read more about the geologic time scale, its origins and its time divisions.  Find out more about plate tectonics, an important geological concept in any time period!