3 types of relative dating
As a result, xenoliths are older than the rock which contains them.
The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds.
Sixteen years after his discovery, he published a geological map of England showing the rocks of different geologic time eras.
Methods for relative dating were developed when geology first emerged as a natural science in the 18th century.
While digging the Somerset Coal Canal in southwest England, he found that fossils were always in the same order in the rock layers.
The principle of Uniformitarianism states that the geologic processes observed in operation that modify the Earth's crust at present have worked in much the same way over geologic time.
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.
Prior to the discovery of radiometric dating in the early 20th century, which provided a means of absolute dating, archaeologists and geologists used relative dating 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.
Photo from Glen Canyon National Recreation Area, Utah.