Comment: 01:42 - 02:51 (01:09)
Source: Annenberg/CPB Resources - Earth Revealed - 10. Geologic Time
Keywords: "geologic time", "James Sadd", "geologic age", orogeny, mountain, "ocean basin", rift, continent
Our transcription: Humorist Mark Twain once remarked "Nothing hurries geology."
He was referring, of course, to the almost imperceptible geologic change that one sees in a human lifetime.
No aspect of this science is more difficult for most people to grasp than the concept of geologic time.
Our lives are governed by events that are measured by clocks in seconds, or minutes, or hours.
At most we may plan months or years in advance.
But to understand the nature of Earth, we need to stretch our concept of time beyond our human experience and into a geologic frame of reference.
Events in Earth's history, such as the development of mountain ranges, the rifting apart of continents, and the creation of new ocean basins have been repeated over and over, and each of these geologic events takes place over many millions of years.
The estimated age of Earth itself is over 4.6 billion years, an incomprehensibly vast period of time.
Geology School Keywords