Paleontology seeks to map out how life evolved across geologic time.
Because rock sequences are not continuous, but may be broken up by faults or periods of erosion, it is difficult to match up rock beds that are not directly adjacent.
Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data.
The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them: Fossil sequences were recognized and established in their broad outlines long before Charles Darwin had even thought of evolution.
Students should be able to understand the principles and have that as a background so that age determinations by paleontologists and geologists don't seem like black magic. Geologists in the late 18th and early 19th century studied rock layers and the fossils in them to determine relative age.
William Smith was one of the most important scientists from this time who helped to develop knowledge of the succession of different fossils by studying their distribution through the sequence of sedimentary rocks in southern England.