Most sedimentary rocks are formed in level layers. Therefore, the occurrence of tilted rock layers is evidence of mountain building. ... Tilting can also result when rocks are pushed upward, or uplifted. In some areas of the world, rock layers are so severely tilted that they may be bottom side up. Layered rocks form when particles settle from water or air. Steno's Law of Original Horizontality states that most sediments, when originally formed, were laid down horizontally. ... Rock layers are also called strata (the plural form of the Latin word stratum), and stratigraphy is the science of strata.
