November 2,2011. Objective: To learn how geologists infer the logical sequence of events and establish a probable relative age for a series of rock layers. Agenda: Law of superposition notes Text book questions Page 204-205 answer questions 4,12,13 Geologic Timeline hanging
Principle of Cross-Cutting Relationships
• The principle of cross-cutting relationships states that when a fault cuts through rock layers, or when magma intrudes other rocks and crystallizes, we can assume that the fault or intrusion is younger than the rocks affected.
• An unconformity represents a long period during which deposition stopped, erosion removed previously formed rocks, and then deposition resumed.
• A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.
Correlation is establishing the equivalence of rocks of similar age in different areas.