He also found that certain animals were in only certain layers and that they were in the same layers all across England.Due to that discovery, Smith was able to recognize the order that the rocks were formed.Picture from Glen Canyon National Recreation Area, Utah.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.While digging the Somerset Coal Canal in southwest England, he found that fossils were always in the same order in the rock layers.Prior to the discovery of radiometric dating which provided a means of absolute dating in the early 20th century, archaeologists and geologists used this technique to determine ages of materials.
From top to bottom: Rounded tan domes of the Navajo Sandstone, layered red Kayenta Formation, cliff-forming, vertically jointed, red Wingate Sandstone, slope-forming, purplish Chinle Formation, layered, lighter-red Moenkopi Formation, and white, layered Cutler Formation sandstone.
Sixteen years after his discovery, he published a geological map of England showing the rocks of different geologic time eras.
The Permian through Jurassic stratigraphy of the Colorado Plateau area of southeastern Utah is a great example of Original Horizontality and the Law of Superposition, two important ideas used in relative dating.
As he continued his job as a surveyor, he found the same patterns across England.
Relative dating is the science of determining the relative order of past events (i.e., the age of an object in comparison to another), without necessarily determining their absolute age, (i.e.
In geology, rock or superficial deposits, fossils and lithologies can be used to correlate one stratigraphic column with another.