Methods for relative dating were developed when geology first emerged as a natural science in the 18th century.
Due to that discovery, Smith was able to recognize the order that the rocks were formed.
Sixteen years after his discovery, he published a geological map of England showing the rocks of different geologic time eras.
These strata make up much of the famous prominent rock formations in widely spaced protected areas such as Capitol Reef National Park and Canyonlands National Park.
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.
Assuming a constant natural radiation level, the last drainage of the trapped electrons can be dated back to several hundred thousand years.