Chapter 21 Fossils and the Rock Record Geologic
- Slides: 18
Chapter 21 Fossils and the Rock Record
Geologic History Principles n Law of Uniform Processes n Law of Superposition n Law of Cross-cutting Relationships n Law of Included Fragments
Law of Uniform Processes n The processes which are changing the earth’s surface today are the same processes which acted in the past
Law of Superposition n The oldest rock layer is on the bottom of an undisturbed rock column, and each higher layer is younger
Law of Cross-cutting Relationships n A fault or intrusion is younger than the rock layers it cuts through
Law of Included Fragments n Pieces of one rock found in another rock must be older than the rock in which they are found
Tree Rings n This tree was approximately how old? About 17 years How did you determine this age? By counting the number or light (summer) and dark (winter) rings
Geologic Time Scale n Which represents the longest time interval – era, eon, or epoch? eon n Which of the three eras represents the longest amount of time? paleozoic n Approximately how old is the earth? 4. 6 billion years
A Relative Age: List the following rock layer in chronological order starting with the oldest layer. B C D E F G X H I J K L Y
Relative Age n In the previous slide you know rock layer Y is younger than rock layer C because _________________. Y cuts across C n In the previous slide you know rock layer H is older than rock layer I because _________________. H is under I n In the previous slide you know rock layer X is younger than rock layers D, E, and F because D, E, and F are included in X _________________.
______ Absolute Age: By measuring the percentages of parent and daughter isotopes in some rocks or fossils, an age in years of that object can be determined.
Fossils Picture C shows what two types of fossils, and how do they form? Mold-organism decays Cast-mold fills with minerals Picture D shows what type of fossil? Trace fossil Picture B shows what type of fossil? Actual remains
Chapter 21 Review (clues on next slide) G a s t r o l i t n f p e d c o o s v x p s o u f o n s t s i i i t o e n r o l m i a m n e r b a l c a s e l r i e z a t i m o l d h
Ch 21 Review (continued)
Ch 21 Review (continued) ___1. Nonconformity B – sedimentary over nonsedimentary C ___2. Angular Unconformity- sedimentary over tilted sedimentary ___3. Disconformity. A sedimentary over horizontal sedimentary
Ch 21 Review (continued) paleozoic ancient life end marked by many extinctions, including dinosaurs mesozoic cenozoic recent life
Ch 21 Review (continued)
Ch 21 Review (continued)
- Match the letter
- Compare geologic time with the geologic column.
- Metamorphic rocks
- Rock layers and fossils worksheet
- Chapter 12 geologic time
- Specimen record observation example
- Chapter 3 standardized test practice answers
- A rock climber's shoe loosens a rock and her climbing buddy
- Earth history and geologic time graphic organizer
- How can one type of rock change into another type of rock?
- Igneous rock to metamorphic rock
- Bungee climbing
- Metamorphic igneous and sedimentary rock cycle
- How is the geologic time scale organized
- Geologic time scale in a calendar year
- Caprock
- Geologic history meaning
- Geologic time scale animals
- Fossils