Chapter 17 fossils
What is a widely distributed fossil or narrow range in time, regarded as characteristic of a given geological formation used especially in determining the age of related formations?
Index fossils
What is rare for soft organisms?
It's ra for them to become fossilized
In the mid-1600s who used the bible to calculate earths age?
James Ussher
Who published the theory of the earth?
James hutton
What law is it when layers original, extend in all directions until it thinned out to zero or ended against the edge of another structure or deposit?
Law of lateral continuity
What law says that unless disturbed by an unusual process, younger layers will be on top of older layers?
Law of superposition
What type of environments also have a lot of dissolved oxygen?
Many under water environments
What type of fossils are found in rock that indicate deposition in a marine environment?
Marine fossils
How do most fossils form?
When living things die and are buried by sediment over time then the sediment hardens into rocks and preserve the shape of the organism
When is there near perfect preservation?
When organisms are trapped in tar pits
What can form if a hard part of an organism like a shell is buried in sediment?
A mold can form
What is the Earths age?
4.6 billion years old
How many types of fossils are there?
5
What are the 5 types of fossils?
-mold and casts -petrified field fossils -carbon films -trace fossils -tar, ice, and amber preserves
What parts of an organism usually form a fossil?
Bones, teeth, shells, seed, and wood fibers
What is a solid copy of the shape on an organism; the exact opposite of a mold?
Cast
What is formed free a mold is made in sand or other material fills the mold and over times it hardens and creates a replica of the original organism?
Cast
What is the belief that earths landscape developed by great catastrophes?
Catastrophism
What is the recent life?
Cenozoic
In a marine region where shallow or deep water indicates what?
Climate and glaction
What does the geological time scale do?
Divides geological history into units
In unreformed sequence of sedimentary rocks what is the bed sequence?
Each bed is older than the one above it and younger than the one below it
What will a radioactive element release from its nuclei in order to stabilize?
Energy
What are time periods subdivided into?
Epochs
What says that life on earth has gradually changed over last long period of time?
Evolution
What is a collection of fossils that are found together?
Fossil assemblage
What shows that older rocks contain fossils of simpler organisms and younger rocks contain fossils of more complex organisms?
Fossil record
What shows that some organisms are changed, and some have become extinct?
Fossil records
What reveals tropical reef environments?
Fossiliferous limestones
What is it to convert into a fossil; replace organic with mineral substances in the remain of an organism?
Fossilization
What are the preserved remains or traces of living things?
Fossils
What can be used as time indicates to correlate similar ages in different regions?
Fossils
What is our best form of evidence about earths history?
Fossils
What does each radioactive element have?
Half lfe
What is the time it takes for one half of the atoms in a sample to disintegrate?
Half-life
What do sedimentary deposits or lava flow generally form?
Horizontal layers
What do fossils help provide evidence about?
How life has changed over time
What do fossils help scientist figure out?
How the surface of the earth has changed by giving clues about the earth's past enviorment
What can organisms indicate about a region?
If the region was terrestrial or marine
Where do coal beds form?
In tropical environments
What is prices of one rock that is contained within another?
Inclusion
What is a fossil with widespread geographic rage but which is restricted in time to a brief existence?
Index fossil
What is a widely distributed fossil, of narrow range in time, regarded as characteristics of a given geological formation, used especially in determining the age of related formations?
Index fossil
What is the middle life?
Mesozic
What is a hollow area in the sediment in the shape of an organism or part of an organism?
Mold
What is the impression of an organism that is left behind?
Mold
What is the most common fossil form?
Mold and casts
Why do most organism decay quickly?
Most environments are exposed to open air and are in contact with plenty of oxygen so the soft tissues decay quickly
Why is fossilization very rare?
Most organisms will either be eaten by scavengers or decomposed by microorganisms after it dies
What established Stenos law?
Nicolaus Steno
What are the types of Unconformities?
Nonconformity, angular, disconfirm its
How do carbon films form?
Organisms get covered with sediment and all elements but the carbon evaporates leaving behind and thin black carbon film
What might happen in the case of the fossil completely dissolving?
Other minerals replace them
What is the ancient life?
Paleozoic
What is a fossilization process whereby additional minerals are deposited in the pore spaces of originals hard animal parts?
Perminerlization
What is impregnated by mineral matter from the ground, lakes, or oceans?
Plant minerals, bones, and shells
What do marine fossils on the top of mountains indicate?
Plate tectonics and uplift
What type of fossils include organisms that have been covered with tar, sap(Amber), or ice, preserving the organism and protecting the body from decay?
Preserved remains
What is it when an igneous intrusion or fault cuts across other rocks of any type the intrusion is younger than the layers that are cut across?
Principle of cross cutting
What is it when fossils succeed one another in a definite and de terminal order, and therefor any time period can be recognized by its fossil content?
Principle of fossil succession
What is used to accurately determine numbers a, dates?
Radioactivity
What is the process in which a radioactive form of an element is converted into a no radioactive product at a regular rate?
Radioactivity decay
What is essential for preservation?
Rapid burial
Placing rocks and events in sequence means what?
Relative date
What type of rocks are fossils usually found in?
Sedimentary rocks
What part of an organism usually decays?
Soft tissue parts
What does the fossil record lead to?
The belief that life of earth has changed or evolved over time
What might fossils indicate about climate?
The climate at the time of burial
What is the rate of burial and post-Morton environment determined by?
The condition of the fossil
What is Stenos law?
The oldest layers are on the bottom, the youngest layers on on the top
How do you form a petrified fossil?
The organism is covered with sediment and then water rich with dissolved minerals over that sediment, then over time the minerals soak into the cells of the organism then the water evaporates and the stones hardens preservers the organism
What is the key to the past?
The present
What is a fossil of an animals or plant but it not formed from the organism itself?
Trace fossil
What are the activities of ancient organisms captured by?
Trace fossils
What are tracks, trials, burrows, or nests that show activity of an organism?
Trace fossils
What are rare soft tissue fossils preserved by?
Tree sap (from example: Amber tree)
What does petrified mean?
Turned into stone
What is a break in the rocks record?
Unconformities
Why is a theory that rejects the idea that catastrophic forces were responsible for the current conditions on the earth?
Uniformitarianism
How is geological time created?
Using relative dates
When do organisms decompose more quickly?
When they are in contact with oxygen
What type of geography does index fossils have?
Widespread geography
Who came up with the principle of fossil succession?
William "Strata"Smith
Who is the fresh prince of geology?
William "strata" smith
What may dissolve and be replaced by minerals?
Wood fibers and cellulose
What is the age of rocks compared to other rocks?What is the exact age of rocks in years?
relative age absolute age
