Comment: 21:25 - 22:28 (01:03)
Source: Annenberg/CPB Resources - Earth Revealed - 8. Earth's Structures
Keywords: "James Sadd", "geologic structure", "economic geology", oil, strata, permeability, impermeability, fold
Our transcription: Geologic structures are also useful, not only for what they reveal about Earth's past, but because of their economic role as well.
n this regard, folds are especially important.
Understanding folds and the way they form is not only intriguing from a scientific point of view, it can also have enormous economic benefits as well.
The compressive stress that folds rocks can also contribute to the formation of petroleum and to the structures that trap it.
For example, many folded regions are composed of alternating permeable and impermeable rock layers.
Some of the permeable strata contain water and oil, which actually flow through the rocks themselves.
In fact, this flow is sometimes driven by the same compressive stress that folds the rock layers.
Because petroleum is lighter than water, it tends to float to the highest point in the fold, and it will be trapped there if the overlying layer is impermeable.
Geology School Keywords