Comment: 00:40 - 01:55 (01:15)
Source: Annenberg/CPB Resources - Earth Revealed - 15. Weathering and Soils
Keywords: introduction, "Cleopatra's Needle", mud, Egypt, "United States", atmosphere, humid, "New York City", salt, weathering, "granitic rock", rock, "Earth's surface"
Our transcription: Even after 35,000 years the hieroglyphics on this ancient Egyptian obelisk stand out with impressive clarity.
But this obelisk known as Cleopatra's Needle, is in far less pristine condition.
After lying half buried in mud for years, it was shipped from Egypt to the United States in the late 1800's.
And placed in the very humid atmosphere of New York City.
Here, the damp air reacted with natural salts absorbed from Egyptian mud to cause a great deal of damage to its surface.
The reason for the contrast between the two monuments can be summed up in one word, "weathering."
Like the granitic rocks of the Egyptian monuments all the rocks on the earth's surface are affected by weathering.
Which is really the way rocks adapt themselves to the environment of earth's surface.
Geology School Keywords