Ch09_Outline - Chapter 9 Geologic Time Relative dating Law...

Info icon This preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 9 Geologic Time Relative dating Law of superposition Developed by Nicolaus Steno in 1669 In an undeformed sequence of sedimentary rocks (or layered igneous rocks), the oldest rocks are on the bottom Superposition is well illustrated by the strata in the Grand Canyon Figure 9.2
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 Relative dating Principle of original horizontality Layers of sediment are generally deposited in a horizontal position Rock layers that are flat have not been disturbed Principle of cross-cutting relationships Younger features cut across older feature Cross-cutting relationships Figure 9.4 Relative dating Inclusions An inclusion is a piece of rock that is enclosed within another rock Rock containing the inclusion is younger Unconformity An unconformity is a break in the rock record produced by erosion and/or nondeposition of rock units
Image of page 2