Chapter 3 The Rock and Fossil Record Sections 1-5 Pages 58-89

Principle of Uniformitarianism The Principle of Uniformitarianism – a principle that states that James Hutton wrote Theory of Earth about the processes that we observe (_______ and _________) remain uniform (do not change) over time

Uniformitarianism vs. Catastrophism Uniformitarianism did not gain acceptance until Charles Lyell published Principle of Geology in 1833 to prove Hutton correct with his new evidence Catastrophism: principle that states: Remained Geology’s guided principle until 1830’s

Modern Geology Late 20 th century: Stephen Gould indicated that while most of Earth’s history is gradual, sometimes catastrophes play a part ( asteroid striking Earth, change global climate or cause extinction) Mixture of both ____________ and ___________

Paleontology- study of past life (fossils) m/watch?v=B7zo2zY1Z qg m/watch?v=B7zo2zY1Z qg

Relative Dating Determining whether an object is older or younger than other objects or events Geologists use rocks and fossils

Principle of Superposition The principle that states However, sometimes the oldest rocks are not on the bottom due to _________ ______ (tilting, folding and breaking)

Geological Column Used to help geologists, they combine data from all the known undisturbed rock sequences around the world Geologists use the geological column to

Disturbed Rock Layers Geologists use the relationship between rock layers and the features that cut across them to assign relative ages to the features and the layers _______, ________, _________ and ________ are examples of features that cut across rock layers

Gaps in the Record- Unconformities Missing rock layers create breaks in rock-layer sequences called _________ An ___________ is a surface that represents a missing part of the geological column Unconformities also represent missing time ____________- stoppage of deposition when a supply of sediment is cut off ___________- (wind and water) allow deposition

Types of Unconformities _____________: part of a sequence of parallel rock is missing. (thousand to millions of years) ______________: found where horizontal sedimentary rock layers lie on top of eroded surface of older intrusive ingenious or metamorphic rock. (millions of years) _______ __________: found between horizontal and sedimentary rock layers and rock layers that have been tilted or folded. (millions of years)

Absolute Dating The process of establishing the age of an object by determining the number of years it has existed is called ________ _________.

Radioactive Decay Unstable isotopes: radioactive Radioactive isotopes tend to break down into stable isotopes of the same or other elements in a process called _________ ________. Occurs at a steady rate, scientists use the relative amounts of stable and unstable isotopes present in an object to determine the object's age.

Dating Rocks After the unstable isotope breaks down into a stable isotope, the stable isotope may be of the same element or more often a different element. The unstable radioactive isotope is called the _______ ________. The stable isotope produced is called the ________ ________. Rate of decay is __________. Scientists compare the amount of parent isotopes to the daughter isotopes to determine the age of rock. The more daughter material, ___________________.

Radioactive Decay bject=physics&jumpTo=re/15Ms1 bject=physics&jumpTo=re/15Ms1

Radiometric Dating If you know the rate of decay for a radioactive element, you can determine the ________ _____ of the rock. Based on a parent to daughter ratio, you can determine the absolute age, this process is called _________ __________. A ______ _______ is the time that it takes one half of the radioactive sample to decay. After every half-life, the amount of parent material decreases by one-half. ½, ¼, 1/8, 1/16 Try this example: Carbon 14’s half-life is 5, 730 years. How old will the object containing this be when ¼, 1/8, 1/16, 1/32 of it’s Carbon 14 remains.

Types of Radiometric Dating ________ ______ Method: used for rocks older than 10,000 years old. ________ ______ Method: used for rocks more than 10 million years old ________ _______ Method: used for rocks over 10 million years old ________ ____ _______: used for dating _______ things that lived within the last 50,000 years

Fossilized Organisms A _______ is the remains or physical evidence of an organism preserved by geological processes Fossils in _____: sometimes decaying organisms get quickly buried by sediment (rock), then the sediment becomes a rock. The harder parts of the animal (bones) become well preserved in this newly formed rock. Fossils in ________: Organisms (insects) get caught in soft sticky tree sap which hardens and preserves them.

Fossilized Organisms ______________: process in which minerals replace an organism’s tissues. _______________ is when pore space of an organism’s hard tissue bone or wood) is replaced with minerals. _____________ is when the organism’s tissues are completely replaced by minerals. (Petrified wood)

Fossilized Organisms Fossils in _________: thick, sticky pools of asphalt on Earth’s surface (La Brea in Los Angeles), trapped and preserved organisms from 38,000 years ago! Frozen _________: the last ice age has preserved many types of fossils since the extreme cold drastically slows down decay (Wholly Mammoth, Siberian tundra)

Trace Fossils Any naturally preserved evidence of animal activity is called a _____ fossil. T_____ B_______ C________ (animal dung)

Molds and Casts A ______ is a cavity in rock where a plant or animal was buried. A _____ is an object when sediment fills a mold and becomes rock.

Using Fossils to Interpret the Past The fossil record is __________ because most organisms never became fossils…and some have not been discovered. The fossil record helps reveal a history of ____________ change. Using the fossils of plants and land animals, scientists can reconstruct past _________. To fill in the missing information about changes in organisms in the fossil record, paleontologists look for __________ between fossilized organisms or between fossilized organisms and their closest living relative.

Using Fossils to Date Rocks ________ ______ are fossils of organisms that lived during a relatively short, well-defined geological time span. _________: tropites (mollusk/squid like), mya _________: phacops (horseshoe crab) 400 mya

Geologic Time The layers in the Grand Canyon represent nearly __ _______ years of Earth’s history. Well preserved plant and animal fossils are common in ______ River because of fine- grained lake-bed sediments.

Geological Time Scale The Geological Time Scale accounts for Earth’s entire history. It is divided into 4 major parts called _____. Dates are estimates. Represents about 4.6 billion years of Earth’s history.

Divisions of Time in size order (greatest to smallest) _____: largest division of time, 4 major eons- Hadean, Archean, Proterozoic, and Phanerozoic. ____: there are 3 eras in the Phanerozoic Eon _______: the 3 eras are divided into periods _______: the periods are divided into epochs

Extinction The death of every member of the species. Can be caused by….

Paleozoic Era ______ life flourished ______ plants appeared Amphibians and reptiles Insects Largest mass extinction in Earth’s history….cause? Ocean currents?

Mesozoic Era Age of the ________ Small mammals Dinosaurs and birds Extinction….cause?.... Global climate?

Cenozoic Era Age of ________ Mammals competed with dinosaurs Due to climate change…mammals better suited for environment