Principles of relative dating in geology
Different ways to correlate: -Physical continuity- can physically trace a rock unit from one area to another.-Similarity of rock type- 2 rocks similar from different places, may be the same.
The shorter the range of the fossil, the more accurate the correlation. -oldest rocks dated are from Greenland, Minnesota, etc.But the faults do not appear to continue into the coal seam, and they certainly do not continue into the upper sandstone.So we can infer that coal seam is younger than the faults (because it disrupts them), and of course the upper sandstone is youngest of all, because it lies on top of the coal seam.The image is about 7 m across.) [SE photo] An unconformity represents an interruption in the process of deposition of sedimentary rocks.Recognizing unconformities is important for understanding time relationships in sedimentary sequences.