Adult chat fun - 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.
-Correlation by fossils- same fossil or fossil assemblage in widely separated rocks are same age. age of rock = number of half lives gone by X half life of isotope pair used How old is the Earth?
The shorter the range of the fossil, the more accurate the correlation. -oldest rocks dated are from Greenland, Minnesota, etc.
Exercise 8.1 Cross-Cutting Relationships The outcrop shown here (at Horseshoe Bay, B. Buff/pink felsic intrusive igneous rock present as somewhat irregular masses trending from lower right to upper left 2. A 50 cm wide light-grey felsic intrusive igneous dyke extending from the lower left to the middle right – offset in several places Using the principle of cross-cutting relationships outlined above, determine the relative ages of these three rock types.