29 3. Law of Cross-Cutting Relationships: Any feature that cuts across a rock or body of sediment must be younger than the rock or sediment that it cuts across such as fractures, faults or igneous intrusions
30 The igneous intrusion H cuts across the layers A,B,C etc…so H is younger than all the rest…
31 4. Law of Inclusions: Rocks or fossils that have become included in another rock or body of sediment must be older than the rock or sediment into which it has been incorporated.
32 Trilobite existed first…then the orange sediment was deposited later…trilobite is older than the orange sediment…
33 5. Law of Unconformities: Gaps in the geologic record that formed wherever layers were not deposited for a time or else layers were removed by erosion
40 This is a sequence of stratified rock. A is the oldest because it is on the bottom of the series of layers. Each layer is distinct. Layer D is the youngest because it is on top. This is a case of Original Horizontality and Superposition.
41 This is an example of an angular unconformity. Layers A, B, C and D are tilted. They were originally horizontal until an episode of tectonics forced these layers into a non horizontal position. Event E is an erosional surface. It is an example of Cross Cutting Relationships. F is the topmost layer and so it is the youngest. A is at the bottom, so it is the oldest.
42 Layers A, B, C, and D were originally horizontal until an episode of tectonics formed these layers into a geologic structure called an anticline. Erosional event E crosscuts the top of the anticline. Layers F and G were deposited later, then igneous intrusion H cross cut all layers, making it the youngest of all the events.
43 Igneous body A existed first, then came along igneous intrusion B. C cut across later making it the youngest, while A is the oldest.
44 Layers A, B and C were deposited first. Fault D cut across A,B,and C. Erosional surface F cut across Fault D and a layer of shale E deposited on top of F.