Nonconformity Essay

Additionally, the principle of original horizontality establishes that when rock layers are flat, they have not been disturbed and therefore are in their original horizontal sequence. Using the Grand Canyon as an example, scientists recognize that layers still have their original horizontality because they have not been folded and thus they have not experienced significant crustal disturbances.

Furthermore, relative dating uses the principle of cross-cutting relationships which states that features which cut through rocks must have formed after the rocks they cut across. This principle is important in understanding geologic time because it demonstrates that the material being broken through must be older than the material breaking through

Contrastingly, an unconformity represents a long period of time during which deposition occurred instead of erosion, which removed rocks that were previously formed. There are three types of unconformities: angular unconformity, disconformity, and nonconformity. An angular unconformity contains titled or folded sedimentary rocks which are later covered by fresher and flatter strata. The second type, a disconformity, is a gap in the rock record which represents a period of erosion rather than deposition. The final type is a nonconformity, in which younger strata lie atop older metamorphic or intrusive igneous rocks. A period of uplift and erosion must occur in order for a nonconformity to develop. Once again using the Grand Canyon as an example, the sediment contained in the Grand Canyon contains all three types of unconformities which represent a long period where geologic time was not

The principle of inclusions states that rock mass adjacent to another containing an inclusion must have formed first, in order to offer the rock fragments. Inclusions are fragments of a rock enclosed inside of another rock, which means that the rock which contains inclusions is the younger of the two.

Absolute dating uses radioactivity to discover the geological age of strata. Prior to the discovery of radioactivity, relative dating was the only available option for scientists. Absolute dating can be done through several methods, one of which is radiometric dating. This process uses the known rates of decay for isotopes that have been accurately measured and do not vary under altered physical conditions, to determine the exact age of strata