Original horizontality relative dating
The Law of Superposition, which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century.
The regular order of occurrence of fossils in rock layers was discovered around 1800 by William Smith.
The most obvious feature of sedimentary rock is its layering.
This feature is produced by changes in deposition over time.
Relative time places events or formations in order based on their position within the rock record relative to one another using six principles of relative dating.
Relative time can not determine the actual year a material was deposited or how long deposition lasted; it simply tell us which events came first.
Your goal is to study the smooth, parallel layers of rock to learn how the land built up over geologic time.
Photo from Glen Canyon National Recreation Area, Utah.With this in mind geologist have long known that the deeper a sedimentary rock layer is the older it is, but how old?Although there might be some mineral differences due to the difference in source rock, most sedimentary rock deposited year after year look very similar to one another.This aspect of Werner's model was useful for explaining the origin of tilted sedimentary rocks.(dark brown) Flat lying sedimentary rocks were eventually precipitated.
(light brown) Next, fossil-rich sedimentary rocks were precipitated.