Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Earth Systems 3209 Unit: 2 Historical Geology Reference: Chapters 6, 8; Appendix A & B

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Interpreting Cross-Section Diagrams using Relative Dating Principles Unit 2: Topic 2.3 Focus on...  demonstrating how relative dating principles and different geologic concepts can be used to determine the history of formation of sample rock sequences (cross-sections).

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Using Relative Dating Principles to Interpret Geologic Cross Sections Relative Dating Principles Include: 1.Principle (Law) of Superposition 2.Principle of Original Horizontality 3.Principle of Cross-Cutting Relationships 4.Principle of Inclusions 5.Unconformities - Angular Unconformity - Disconformity - Nonconformity Review Principles:

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Rock Symbols Granite Basalt Contact Metamorphism xxxxxxx

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Using Relative Dating Principles to Interpret Geologic Cross Sections Rock UnitDescription A B C D E F X

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Historical Walk Through a Cross Section Common Questions Focus On:  Age of one rock unit compared to another.  Determine whether an igneous rock unit is intrusive or extrusive.  Identify folding and faulting in a cross section.  Identify crosscutting, igneous rock units and faults.  Identify contact metamorphism.  Identify the different unconformities.  List the rock layers from oldest to youngest.

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Example 1: Use the diagram below to answer the questions that follow. KEY Conglomerate Sandstone Shale Limestone Coal Granite Basalt A B C D G E F H L J K (i)List the geologic events, represented by letters A to K, from oldest to youngest. Oldest Youngest ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___ (ii) Which type of unconformity is represented by K? ________________________ (iii)Explain how you know which letter identifies the oldest igneous rock unit. ___________________________________

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Example 2: Determine whether rock unit “A” represents a buried lava flow or an igneous intrusion. A Key:Contact Metamorphism XXXXXXXXXXX Buried lava flow would only have the contact metamorphism beneath the igneous rock unit. An igneous intrusion would have contact metamorphism both beneath and above the igneous rock unit.

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Your Turn... Take the time and complete the following questions... (Solutions to follow) Questions: Use the diagram to answer questions (i) and (ii) (i)Does A represent an intrusive feature or extrusive feature? Explain (ii)Arrange all letters in the order in which they occurred beginning with the oldest. Oldest Youngest ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Solutions... Questions: (i)Does “A” represent an intrusive feature or extrusive feature? Explain Rock unit A represents an intrusive rock unit. The presence of contact metamorphism surrounding the entire igneous rock unit suggests that magma intruded the surrounding rock units where it baked (contact metamorphism) the rocks that it contacted.

Copyright © 2014 All rights reserved, Government of Newfoundland and Labrador Solutions... Questions: (ii)Arrange all letters in the order in which they occurred beginning with the oldest. Oldest Youngest ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___, ___