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.Geological events being significant occurrences as a result of the earth system.Whilst these islands have been shaped over many thousands of years by events such as weathering and erosion, particularly due to glaciation, the main events which formed the islands were two volcanic eruptions.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.Though relative dating can only determine the sequential order in which a series of events occurred, not when they occurred, it remains a useful technique.Relative dating by biostratigraphy is the preferred method in paleontology and is, in some respects, more accurate.
These islands were formed by multiple geological events.
If a geologist claims to be 45 years old, that is an absolute age.
Superposition: The most basic concept used in relative dating is the law of superposition.
Geologists generally know the age of a rock by determining the age of the group of rocks, or formation, that it is found in.
The age of formations is marked on a geologic calendar known as the geologic time scale.