| Part of a series on |
| Geology |
|---|
 |
The principle of original horizontality states that layers of sediment are originally deposited horizontally under the action of gravity.[1] It is a relative dating technique. The principle is important to the analysis of folded and tilted strata. It was first proposed by the Danish geological pioneer Nicholas Steno (1638–1686).
From these observations is derived the conclusion that the Earth has not been static and that great forces have been at work over long periods of time, further leading to the conclusions of the science of plate tectonics; that movement and collisions of large plates of the Earth's crust is the cause of folded strata.[2]
As one of Steno's Laws, the principle of original horizontality served well in the nascent days of geological science.[3] However, it is now known that not all sedimentary layers are deposited purely horizontally. For instance, coarser grained sediments such as sand may be deposited at angles of up to 15 degrees, held up by the internal friction between grains which prevents them slumping to a lower angle without additional reworking or effort. This is known as the angle of repose, and a prime example is the surface of sand dunes.
Similarly, sediments may drape over a pre-existing inclined surface: these sediments are usually deposited conformably to the pre-existing surface. Also, sedimentary beds may pinch out along strike, implying that slight angles existed during their deposition. Thus the principle of original horizontality is widely, but not universally, applicable in the study of sedimentology, stratigraphy, and structural geology.
YouTube Encyclopedic
-
1/3Views:15 429269 55226 314
-
Law of original horizontality
-
Laws of Relative Rock Dating
-
Law of Superposition
Transcription
See also
- Law of superposition
- Principle of cross-cutting relationships
- Principle of faunal succession
- Principle of lateral continuity
References
- ^ Levin, H.L. (2009). The Earth Through Time (9 ed.). John Wiley and Sons. p. 15. ISBN 978-0-470-38774-0. Retrieved 28 November 2010.
- ^ Michael E. Brookfield, Principles of Stratigraphy, Blackwell Publishing, 2004, p. 116, ISBN 140511164X
- ^ Kardel, Troels, ed. (2013). Nicolaus Steno: Biography and Original Papers of a 17th Century Scientist. Berlin: Springer. ISBN 978-3-642-25078-1.
Geologic principles and processes | ||
|---|---|---|
| Stratigraphic principles |  | |
| Petrologic principles | ||
| Geomorphologic processes | ||
| Sediment transport | ||
This page was last edited on 21 October 2022, at 18:45