The principle states that “at the time when any given stratum was being formed, all the matter resting upon it was fluid, and, therefore, at the time when the lower stratum was being formed, none of the upper strata existed” (Alden, 2018).
This principle reasons that rocks get arranged in a vertical order like sediments with the new one on top of the old one allowing geologists to assemble the fossil fuel life succession.
The Principle of Original Horizontality
This principle states that “strata either perpendicular to the horizon or inclined to it, were at one time parallel to the horizon” (Alden, 2018).
This principle reasons that rocks that are tilted weren’t originally that way and must have been acted upon by an external force for them to tilt.
The Principle of Lateral Continuity
This principle states that “material forming any stratum were continuous over the surface of the Earth unless some other solid bodies stood in the way” (Alden, 2018).
This principle was able to link two identical rocks separated by a river which meant that they were separated by possibly erosion over time.
Principle of Cross-Cutting Relationship
This principle states that “if a body or discontinuity cuts across a stratum, it must have formed after that stratum” (Alden, 2018).
This principle is critical in understanding the sequence of geological events such as deformation, faulting amongst others. It means that if a rock is cut by magma, as an example, it means that rock existed before the intrusive magma.
Difficulty in using sedimentary and metamorphic rocks for radiometric age dating
Sedimentary rocks get formed as a result of compacting and cementing existing rock into a new one. The formation of a new one means that the grains of the newly formed rock have different ages, and hence it becomes difficult to measure the age of the whole rock.
The difficulty with metamorphic rock is that metamorphism, which refers to the pressure and heat applied on the rocks, occurs over long intervals causing different grains to have different ages. This difference means that distinct grains in the rock will result in different ages if one uses radiometric dating.
Reference
Alden, A. (2018).Steno Started Geology With a Few Simple Principles. ThoughtCo. Web.